MAX25221BATV [MAXIM]
Automotive 4-Channel TFT-LCD Power Supply with VCOM Buffer;型号: | MAX25221BATV |
厂家: | MAXIM INTEGRATED PRODUCTS |
描述: | Automotive 4-Channel TFT-LCD Power Supply with VCOM Buffer CD |
文件: | 总55页 (文件大小:722K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
Click here to ask about the production status of specific part numbers.
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
General Description
Benefits and Features
The MAX25220/MAX25221/MAX25221B are 4-channel
TFT-LCD power ICs that provide symmetrical positive
● High Integration
• Synchronous Boost Provides AVDD of 4.2V to
10.5V at up to 200mA
AVDD and negative NAVDD supplies as well as VG
ON
and VG
gate supplies. In addition, a VCOM buffer with
• NAVDD Inverter Output at up to -200mA
OFF
output voltage range above and below ground and a tem-
• 15mA VG
Output (7.6V to 20.2V) from 3x
ON
perature measurement block are integrated (MAX25221/
B).
Regulated Charge Pump
• VG
(-18.2V to -5.6V) from Regulated Charge
OFF
Pump at up to -15mA (charge-pump doubler)
• Controlled Sequencing during Power-On and
Power-Off of All Rails
• VCOM Output Range +1V to -2.49V in 6.83mV
Steps (MAX25221)
• NTC Input for Temperature Measurement/
Compensation (MAX25221)
The devices contain non-volatile memory so that the val-
ues of all outputs can be calibrated for the lifetime of the
device (maximum five times).
2
Programming is carried out using the built-in I C interface,
which can also be used to read back diagnostic informa-
tion. A stand-alone mode is also available.
The temperature sensor interface block measures the
temperature optionally allowing the VCOM output voltage
to be adjusted depending on the measured temperature.
● Low EMI
• 420kHz/2.1MHz Switching Frequency with Spread
Spectrum
The MAX25220/MAX25221/MAX25221B are available in
a TQFN package and operate in the -40 to 125°C temper-
ature range.
2
● I C Control/Diagnostic Interface with FLTB (Interrupt)
Output
• UV diagnostics on All Outputs
● Versatile
Applications
• Non-Volatile Output Voltage Settings on AVDD/
● Infotainment Displays
● Central Information Displays
● Instrument Clusters
NAVDD, VG , VG
, VCOM, and Sequencing
ON
OFF
• Supports Stand-Alone Operation Mode after
Programming
• Compact 5mm x 5mm TQFN32 Package
● AECQ100 Grade 1
Ordering Information appears at end of datasheet.
19-100803; Rev 4; 11/20
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
Simplified Block Diagram
RREF TEMP
V18
IN
IN
DAC
REG
VCOM
8b ADC FOR
TEMP
COMPENSATION
VCOMN
BST
NAVDD
NEG.
REGULATOR
VCB
PGVDD
FC2+
TFT BOOST
CONTROL
420kHz/2.1MHz
UVLO
HVINP
LXP
FC2-
PGND
POSITIVE
CHARGE PUMP
FC1+
0.9V
TEMP
WARNING,
SHUTDOWN
FC1-
HVINP
AVDD
VGON
REFERENCE
POSITIVE
SOFT-START
AND
VGOFF
DN
DISCHARGE
ENABLE, CONTROL
AND FAULT LOGIC
NEGATIVE
CHARGE PUMP
NEGATIVE
SOFT-START
AND
NAVDD
DISCHARGE
CPGND
EN
FLTB
DGND
INVERTING
REGULATOR
420kHz/2.1MHz
PROGRAMMING
LOGIC &
NV MEMORY
INN
I2C
LXN
MAX25221/B
ADD
GND
SCL SDA
VPROG
www.maximintegrated.com
Maxim Integrated | 2
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
TABLE OF CONTENTS
General Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Benefits and Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Simplified Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Absolute Maximum Ratings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Package Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
TQFN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
TQFN-SW. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Typical Operating Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Pin Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
MAX25220 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
MAX25221/B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Pin Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Functional Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
MAX25220 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
MAX25221/B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Detailed Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Power-Up state . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Switching Frequency. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Stand-Alone Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
2
I C Read-Only Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Source Driver Power Supplies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Gate-Driver Power Supplies. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Sequencing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Sequencing Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
VCOM Buffer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
VCOMN Negative Power Supply. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Limiting the Range of VCOM Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
VCOM Temperature Compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
NTC Connection Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Internal Temperature Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Temperature Compensation Curve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Fault Handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Undervoltage Faults on the Source, Gate and VCOM Outputs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Thermal Warning and Shutdown. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
NV Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Auto-Refresh Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
www.maximintegrated.com
Maxim Integrated | 3
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
TABLE OF CONTENTS (CONTINUED)
BURN, REBOOT and RESTART Commands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
2
I C Interface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
2
I C Slave Addresses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Parity Checking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Register Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
MAX25220/MAX25221/MAX25221B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Register Details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Applications Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Boost Converter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Boost Converter Inductor Selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Boost Output Filter Capacitor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Boost Input Filter Capacitor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Setting the AVDD Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
NAVDD Inverting Regulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
NAVDD Regulator Inductor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
NAVDD External Diode Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
NAVDD Output Capacitor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Setting the VG
and VG
Output Voltages. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
OFF
ON
VG
Voltage Higher than Three Times AVDD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
ON
4x Charge Pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
VCOM Block. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
VCB Transistor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
VCOM Temperature Compensation Example. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Sample VCOM Temperature Compensation Curve. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Using the NV Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Layout Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Typical Application Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
MAX25220 Applications Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
MAX25221 Applications Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
www.maximintegrated.com
Maxim Integrated | 4
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
LIST OF FIGURES
Figure 1. Sequencing Example (Sequence 1, Not to Scale). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Figure 2. Possible NTC Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Figure 3. Temperature Compensation Curve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Figure 4. Quadrupler Charge-Pump at 2.1MHz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Figure 5. Sample VCOM Temperature Compensation Curve. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
www.maximintegrated.com
Maxim Integrated | 5
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
LIST OF TABLES
Table 1. DEVICE BEHAVIOR AFTER START-UP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Table 2. Available Sequences. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Table 3. VCOM Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Table 4. FLTB Duty Cycle in Stand-Alone Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
2
Table 5. I C Slave Addresses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Table 6. ADC Result vs Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Table 7. VCOM Setting Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
www.maximintegrated.com
Maxim Integrated | 6
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
Absolute Maximum Ratings
IN, INN to GND......................................................... -0.3V to +6V
IN to INN................................................................ -0.3V to +0.3V
V18 to GND ........................................................... -0.3V to +2.2V
HVINP to GND.......................................................... -0.3V to 16V
LXP, AVDD to GND.................................. -0.3V to HVINP + 0.3V
BST to GND............................................................ -0.3V to +16V
BST to LXP............................................................ -0.3V to +2.2V
LXN to INN ............................................................. -22V to +0.3V
PGND, CPGND, DGND to GND............................ -0.3V to +0.3V
VCB to GND .......................................... V18 - 22V to V18 + 0.3V
VCOMN to GND....................................... V18 - 6V to V18 + 0.3V
PGVDD, FC1-, FC2-, DN to GND.............-0.3V to HVINP + 0.3V
FC1+ to GND .......................................... -0.3V to PGVDD + 0.3V
FC2+ TO FC1+ .......................................................-0.3V to +22V
VG
to FC2+ ........................................................-0.3V to +22V
ON
FC2+, VG
to GND ..............................................-0.3V to +24V
ON
EN, FLTB, SCL, SDA to GND...................................-0.3V to +6V
ADD, TEMP, R to GND .......................... -0.3V to V18 + 0.3V
REF
V
PROG
to GND .......................................................-0.3V to +14V
Continuous Power Dissipation (Multilayer Board) (T = +70ºC,
A
VG
, NAVDD to GND ............................. IN - 22V to IN + 0.3V
derate 21.3mW/ºC above +70ºC) ...................................2222mW
Operating Temperature Range.............................-40°C to 125°C
OFF
VCOM to GND.................................. VCOMN - 0.3V to IN + 0.3V
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the
device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for
extended periods may affect device reliability.
Package Information
TQFN
Package Code
T3255+6C
21-0140
90-0603
Outline Number
Land Pattern Number
Thermal Resistance, Single-Layer Board:
Junction to Ambient (θ
)
47°C/W
3°C/W
JA
Junction to Case (θ
)
JC
Thermal Resistance, Four-Layer Board:
Junction to Ambient (θ
)
36°C/W
3°C/W
JA
Junction to Case (θ
)
JC
TQFN-SW
Package Code
Outline Number
T3255Y+6C
21-100041
90-100066
Land Pattern Number
Thermal Resistance, Single-Layer Board:
Junction to Ambient (θ
)
47°C/W
3°C/W
JA
Junction to Case (θ
)
JC
Thermal Resistance, Four-Layer Board:
Junction to Ambient (θ
)
36°C/W
3°C/W
JA
Junction to Case (θ
)
JC
For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”, “#”, or “-” in the package code indicates
RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status.
Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer board. For detailed information on package thermal
considerations, refer to www.maximintegrated.com/thermal-tutorial.
www.maximintegrated.com
Maxim Integrated | 7
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
Electrical Characteristics
(V = 3.3V, V
IN
= 3.3V, Limits are 100% guaranteed between T = -40°C and T = +125°C. )
INN
A A
PARAMETER
INPUT SUPPLY
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
IN Voltage Range
IN UVLO Threshold
2.65
2.4
5.5
V
V
IN_UVLO_R
Rising
2.5
2.57
IN_UVLO_HY
S
IN UVLO Hysteresis
100
mV
IN Shutdown Current
IN Quiescent Current
V18 REGULATOR
V18 Output Voltage
V18 Current Limit
I
EN = GND, V = 3.3V, T = 25°C
7
12
µA
IN_SHDN
IN
A
I
V
EN
= V = 3.3V, no switching.
1.5
2.5
mA
IN_Q
IN
1.72
60
1.8
1.88
1.7
V
mA
V18 Undervoltage
Lockout
V18 rising
1.6
1.65
150
V
V18 Undervoltage
Hysteresis
mV
OSCILLATOR
f
bit = 0, dither disabled. Switching
SW
f
frequency for boost, inverter, and charge
pumps.
1950
385
2100
2250
455
BOOSTH
Operating Frequency
kHz
%
f
bit = 1, dither disabled. Switching
SW
f
frequency for boost, inverter, and charge
pumps.
420
±6
BOOSTL
f
BOOSTD
Frequency Dither
BOOST REGULATOR
HVINP Output Voltage
Range
V
V
+ 1
10.5
10.5
V
V
V
V
HVINP
IN
AVDD Output Voltage
Range
4.2
AVDD Adjustment Step
Size
0.1
6.8
AVDD Output
Regulation
avdd[5:0] = 0x1A, full load current and
input voltage range
V
6.664
6.936
AVDD
420kHz switching frequency
2.1MHz switching frequency
87
84
88.5
87
90
90
Oscillator Maximum
Duty Cycle
%
Low-Side Switch On-
Resistance
LXP_RON_LS
I
= 0.1A
0.1
0.1
0.2
0.2
Ω
Ω
LXP
Synchronous Rectifier
On-Resistance
Synchronous Rectifier
Zero-Crossing
Threshold
ZX_TH
70
2
mA
LXP Leakage Current
LXP Current Limit
LXP_L_LEAK
V
= 0V, V
= 10.5V
LXP
20
µA
A
EN
I
Duty cycle = 50%
1.7
2.3
LIMPH
www.maximintegrated.com
Maxim Integrated | 8
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
Electrical Characteristics (continued)
(V = 3.3V, V
IN
= 3.3V, Limits are 100% guaranteed between T = -40°C and T = +125°C. )
INN
A A
PARAMETER
Soft-Start Period
SYMBOL
CONDITIONS
Current-limit ramp
MIN
TYP
MAX
UNITS
t
5
ms
BOOST_SS
INVERTING REGULATOR
2.1MHz switching frequency
INV_MAXDC 420kHz switching frequency
92
88
95
90
Oscillator Maximum
Duty Cycle
%
V
= 2.65V to 5.5V, V
= 6.8V,
AVDD
INN
V
+ V
V
AVDD
NAVDD
NAVDD_AVD
D_REG
1mA < I
load as NAVDD
< 200mA, I
= same
-34
0
34
mV
NAVDD
AVDD
Regulation Voltage
LXN On-Resistance
LXN Leakage Current
LXN_RON
INN to LXN, I
= 0.1A
0.25
0.5
20
Ω
LXN
LXN
V
IN
= 3.6V, V
= V
= -6.8V, T
NAVDD A
LXN_LEAK
µA
= +25°C
LXN Current Limit
Soft-Start Period
I
Duty cycle = 80%
Current-limit ramp
1.55
1.9
5
2.25
A
LIMNH
t
ms
INV_SS
NAVDD Discharge
Resistance
2
kΩ
V
POSITIVE CHARGE-PUMP REGULATOR
VG Threshold for
ON
V
-
HVINP
0.8
Charge-Pump Switching
Enable
FC1-, FC2- Switches
Current Limit, High-side
90
72
120
100
4
mA
mA
Ω
FC1-, FC2- Switches
Current Limit, Low-side
FC1-, FC2- to CPGND
On-Resistance
6.5
FC1-, FC2- to HVINP
On-Resistance
6
10.5
Ω
FC2+ to PGVDD, FC1+
to FC2+ and VG
FC1+ Switches On-
Resistance
to
ON
2.5
4.5
Ω
VG
I C Mode
Voltage Range,
ON
7.6
20.2
V
V
2
VG Adjustment Step
Size, I C Mode
ON
0.2
12
3
2
vgon[5:0] = 0x16, full load current and
> 5V, charge-pump tripler
VG
Output Voltage
V
VGON
11.7
2.2
12.3
3.8
V
ON
ON
V
HVINP
VG
Resistance
Discharge
kΩ
NEGATIVE CHARGE-PUMP REGULATOR
DN Current Limit
75
100
mA
V
VG
2
Voltage Range,
OFF
-18.2
-5.6
I C Mode
www.maximintegrated.com
Maxim Integrated | 9
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
Electrical Characteristics (continued)
(V = 3.3V, V
IN
= 3.3V, Limits are 100% guaranteed between T = -40°C and T = +125°C. )
INN
A A
PARAMETER
Adjustment Step
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
VG
OFF
0.2
V
2
Size, I C Mode
VG Output-Voltage
Accuracy
vgoff[5:0] = 0x16, full load current and
input voltage range, 420kHz operation.
OFF
-10.3
-10
6
-9.7
10
V
Ω
DN On-Resistance,
High-Side
DN On-Resistance,
Low-Side
I
= -10mA
3.5
1.5
6.5
Ω
DN
VG
Discharge
OFF
mA
Current
SEQUENCE SWITCHES
AVDD ON Resistance
AVDD Current Limit
Between HVINP and AVDD, I
200mA
=
AVDD
R
0.5
1
Ω
mA
kΩ
Ω
ONAVDD
ILIM
300
80
600
POS
AVDD Discharge
Resistance
1.2
6
PGVDD On resistance
PGVDD Current Limit
(HVINP-PGVDD), I
= 3mA
9
PGVDD
Expires when PGVDD charging is
completed
100
mA
FAULT PROTECTION
Fault Timeout
tfault[1:0] = 10
60
1.9
1
ms
s
Fault Retry Time
tretry[1:0] = 10 or 11
Stand-alone mode only
FLTB Output Frequency
0.88
1.12
kHz
FLTB Output Duty
Cycle, VG
Fault
or VG
Stand-alone mode only
75
50
%
%
ON
OFF
FLTB Output Duty Cycle
with AVDD, NAVDD or
HVINP Fault
Stand-alone mode only
Stand-alone mode only
FLTB Output Duty
Cycle, VCOM Fault
25
85
40
85
40
85
%
%
%
%
%
%
V
AVDD Undervoltage
Fault Threshold
Relative measurement between HVINP
and AVDD
80
35
80
35
80
90
45
90
45
90
AVDD Short-Circuit
Fault Threshold
Relative measurement between HVINP
and AVDD
NAVDD Undervoltage
Fault Threshold
Measured with respect to AVDD
Measured with respect to AVDD
Of set value
NAVDD Short-Circuit
Fault Threshold
VG
Undervoltage
ON
Fault Threshold
VG Short-Circuit
V
-
ON
HVINP
1.1
VG
Falling
ON
Fault Threshold
www.maximintegrated.com
Maxim Integrated | 10
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
Electrical Characteristics (continued)
(V = 3.3V, V
IN
= 3.3V, Limits are 100% guaranteed between T = -40°C and T = +125°C. )
INN
A A
PARAMETER
Undervoltage
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
VG
OFF
Of set value
80
85
90
%
Fault Threshold
VG Short-Circuit
Fault Threshold
OFF
35
40
10
45
%
Short-Circuit and
Overload Fault Delay
µs
VCOM BUFFER
VCOMN Output Voltage
VCB Output Current
I
= 120mA, V
= -10.5V
NAVDD
-3.5
12
-3.2
21
V
VCOM
5
mA
VCOM Output Current
Limit, Sinking
Dynamic output current, t < t
Dynamic output current, t < t
120
200
200
70
300
300
85
mA
mA
FAULT
FAULT
VCOM Output Current
Limit, Sourcing
I
120
60
LIMCOMP
VCOM Overcurrent
Detection Threshold
of
I
LIMCOMP
VCOM Offset Voltage,
Complete Range
V
load
= -2.49V and V
= +1V, no
VCOM
VCOM
-20
+20
mV
VCOM Offset Voltage,
25°C
T
= 25°C, VCOM = -0.5V
-6
+6
+10
1
mV
mV
V
A
VCOM Offset Voltage
VCOM = -0.5V
Temperature compensation disabled
-10
VCOM Output Voltage
Range
-2.49
VCOM DAC Step Size
VCOM Buffer Slew Rate
VCOM Fault Threshold
6.83
0.72
+0.25
60
mV
V/μs
V
C
+1V
= 10nF, VCOM from -2.49V to
VCOM
Deviation from set voltage
tfault[1:0] = 10
VCOM Fault Detection
Filter Time
ms
VCOM Discharge
Resistance
to GND
9
0
14
22
kΩ
R
REF
INPUT
R
REF
Input Voltage
1.25
V
Range
R
R
ADC Resolution
Conversion Rate
4.88
128
625
mV
kHz
mV
REF
REF
TEMP Voltage
V
TEMP
I
I
= 10 to 500μA
= 10 to 500μA
TEMP
TEMP Current Mirror
Gain
1
μA/μA
TEMP
Internal Temperature
Sensor Voltage
T
A
= 25°C
620
5
mV
mV
R
REF
DAC Offset
www.maximintegrated.com
Maxim Integrated | 11
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
Electrical Characteristics (continued)
(V = 3.3V, V
IN
= 3.3V, Limits are 100% guaranteed between T = -40°C and T = +125°C. )
INN
A A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
mV
R
Error
DAC Full-Scale
REF
5
R
R
DAC Gain Error
DAC Differential
-0.4
+0.4
%
REF
REF
0.5
0.5
LSB
Non-linearity
R
REF
DAC Integral Non-
LSB
Linearity
LOGIC INPUTS and OUTPUTS (EN, SCL, ADD, SDA)
EN Glitch Filter
EN_BLK
10
µs
EN Minimum Low Time
For Reset
C
V18
= 1uF
1
ms
EN Input Logic-High
EN Input Logic-Low
ADD Input Logic-High
ADD Input Logic-Low
1.22
V
V
V
V
0.6
1.22
0.66
12
ADD Input Pulldown
Current
10
μA
V
SCL, SDA Input, Logic-
High
1.22
-1
SCL, SDA Input, Logic-
Low
0.6
+1
V
SCL Input Leakage
Current
µA
V
FLTB, SDA Output Low
Voltage
V
Sinking 5mA
5.5V
0.4
+1
OL
FLTB, SDA Output
Leakage Current
I
-1
µA
LEAK
PROGRAMMING VOLTAGE
V
V
Voltage
Voltage
8.2
8.5
8
8.8
8.2
V
V
PROG
PROG
V
V
rising
falling
PROG
Undervoltage Threshold
V
PROG
Voltage
8.8
9
V
PROG
Overvoltage Threshold
VPROG Input Current
NV Programming Time
THERMAL SHUTDOWN
During NV programming, T = 25°C
9
25
20
mA
ms
A
16
Thermal Warning
Threshold
125
160
15
°C
°C
°C
Thermal-Shutdown
Threshold
T
SHDN
Thermal-Shutdown
Hysteresis
T
SHDN_HYS
www.maximintegrated.com
Maxim Integrated | 12
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
Electrical Characteristics (continued)
(V = 3.3V, V
IN
= 3.3V, Limits are 100% guaranteed between T = -40°C and T = +125°C. )
INN
A A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
2
I C INTERFACE
Clock Frequency
f
0.4
MHz
ns
SCL
Hold Time (Repeated)
START
t
600
HD:STA
SCL Low Time
SCL High Time
t
1300
600
ns
ns
LOW
t
HIGH
Setup Time (Repeated)
START
t
600
ns
SU:STA
HD:DAT
Data Hold Time
Data Setup Time
t
0
ns
ns
t
100
SU:DAT
Setup Time for STOP
Condition
t
600
ns
ns
SU:STO
Spike Suppression
50
Note 1: Note 1: Limits are 100% tested at T = +25°C. Limits over the operating temperature range and relevant supply voltage range
A
are guaranteed by design and characterization.
www.maximintegrated.com
Maxim Integrated | 13
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
Typical Operating Characteristics
(V = +3.3V, F
IN
= 2.1MHz, T = +25 C unless otherwise noted.)
SW
A
www.maximintegrated.com
Maxim Integrated | 14
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
Typical Operating Characteristics (continued)
(V = +3.3V, F
IN
= 2.1MHz, T = +25 C unless otherwise noted.)
SW
A
www.maximintegrated.com
Maxim Integrated | 15
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
Pin Configurations
MAX25220
TOP VIEW
24 23 22 21 20 19 18 17
25
26
27
28
29
30
31
32
16
DN
AVDD
15
14
13
12
11
10
9
HVINP
LXP
SDA
SCL
FLTB
I.C.
PGND
BST
MAX25220
GND
V18
I.C.
DGND
NAVDD
+
ADD
1
2
3
4
5
6
7
8
TQFN
5mm x 5mm
www.maximintegrated.com
Maxim Integrated | 16
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
MAX25221/B
TOP VIEW
24 23 22 21 20 19 18 17
25
26
27
28
29
30
31
32
16
DN
AVDD
15
14
13
12
11
10
9
HVINP
LXP
SDA
SCL
FLTB
PGND
BST
MAX25221/B
RREF
TEMP
DGND
NAVDD
GND
V18
+
ADD
1
2
3
4
5
6
7
8
TQFN
5mm x 5mm
Pin Description
PIN
NAME
FUNCTION
MAX25220
MAX25221/B
Programming Voltage. Apply a voltage of 8.5V to this pin during the programming
of non-volatile registers. Connect to GND through a resistor during normal
operation.
1
1
V
PROG
2
3
2
3
LXN
INN
IC
DC-DC Inverting Converter Inductor/Diode Connection.
Inverting Converter Input. Connect 10μF + 0.1μF ceramic capacitors from this pin
to ground for proper operation.
4
—
4
Internally connected. Leave this pin open.
Drive Output for External npn Pass Transistor for VCOMN regulator. Connect to
the base of the external npn transistor.
—
VCB
5
—
6
—
5
IC
VCOM
IC
Internally Connected. Leave this pin open.
Output of VCOM amplifier.
—
Internally Connected. Connect this pin to GND.
Negative Supply for VCOM Buffer. Connect a ceramic capacitor of at least 1μF
from VCOMN to GND.
—
7
6
7
VCOMN
IN
Supply Connection for Display Bias Circuitry. Bypass IN with local 10μF and 0.1μF
capacitors.
www.maximintegrated.com
Maxim Integrated | 17
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
Pin Description (continued)
PIN
NAME
FUNCTION
MAX25220
MAX25221/B
Enable Input Pin. When EN is low, the device is in shutdown. When EN is taken
high, the device is active. In stand-alone mode, the outputs are turned on in the
stored sequence when EN goes high.
8
8
EN
2
Device Address Select pin. Connect to GND or V18 to Select the Device I C
2
2
Address. See the I C address table. To use stand-alone mode (without I C) leave
the ADD pin open. In this mode, the device turns on all outputs in the programmed
sequence when EN is taken high.
9
9
ADD
10
11
10
11
V18
Output of Internal 1.8V Regulator. Connect a 1μF capacitor from V18 to GND.
Ground Connection
GND
Bootstrap Capacitor Connection for Synchronous Rectifier Driver. Connect a
0.1μF ceramic capacitor between BST and LXP.
12
13
14
15
16
12
13
14
15
16
BST
PGND
LXP
Ground Connection for Boost Switching Device and VCOM Buffer. Connect to
GND using a low-impedance trace.
Switching Node of Boost Converter. Connect the boost inductor between LXP and
IN.
Boost Output and Input to Positive and Negative Charge-Pump Drivers. Bypass
HVINP with a 10μF output capacitor placed close to the pin.
HVINP
AVDD
Switched Output of Boost Converter. Connect a bypass capacitor of value 2.2μF
from AVDD to PGND.
Supply Voltage for Positive Charge Pump. PGVDD is connected to HVINP by
means of an internal switch when the positive charge pump is enabled. Bypass
PGVDD with a ceramic capacitor of 1μF to GND.
17
17
PGVDD
Positive Connection for Second Flying Capacitor. Connect a 22nF capacitor from
FC2- to FC2+.
18
19
20
21
18
19
20
21
FC2+
FC2-
FC1+
FC1-
Negative Connection for Second Flying Capacitor. Connect a 22nF capacitor from
FC2- to FC2+.
Positive Connection for First Flying Capacitor. Connect a 22nF capacitor from
FC1- to FC1+.
Negative Connection for First Flying Capacitor. Connect a 22nF capacitor from
FC1- to FC1+.
Output of Positive Charge-Pump Block. Connect a 1μF capacitor from VG
GND.
to
ON
22
23
24
22
23
24
VG
ON
CPGND
VG
Ground Connection for Charge Pumps.
Output of Negative Charge-Pump Block. Connect a 1μF capacitor from this pin to
GND.
OFF
25
26
27
25
26
27
DN
Negative Charge-Pump Push-Pull Drive Output.
2
SDA
SCL
Bidirectional I C Data Pin.
2
I C Clock Pin.
Open-Drain, Active-Low Fault Output. Connect a pullup resistor from FLTB to a
logic supply ≤5V. In stand-alone mode, the duty cycle of the FLTB pin indicates an
error condition, if present (see Table 4). When the serial interface is used, FLTB is
either a 0 (indicating data to be read from the internal registers) or a 1.
28
29
28
—
FLTB
IC
Internally Connected. Leave this pin open.
www.maximintegrated.com
Maxim Integrated | 18
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
Pin Description (continued)
PIN
NAME
FUNCTION
MAX25220
MAX25221/B
Reference Resistor Pin. When using the temperature compensation function,
—
30
—
31
32
29
—
30
31
32
R
REF
connect a resistor from R
to GND. If unused, leave R
unconnected.
REF
REF
IC
Internally Connected. Leave this pin open.
Temperature Sensor Pin. When using the temperature compensation function,
connect an NTC from TEMP to GND. If unused, leave TEMP unconnected.
TEMP
DGND
NAVDD
Logic Ground.
Negative Source-Driver Output Voltage. Connect ceramic capacitors of value
0.1μF and 10μF from this pin to GND with the smallest capacitor closest to the pin.
www.maximintegrated.com
Maxim Integrated | 19
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
Functional Diagrams
MAX25220
IN
V18
REG
BST
TFT BOOST
CONTROL
420kHz/2.1MHz
PGVDD
FC2+
HVINP
LXP
FC2-
PGND
POSITIVE
CHARGE PUMP
FC1+
FC1-
0.9V
TEMP
WARNING,
SHUTDOWN
HVINP
AVDD
VGON
REFERENCE
POSITIVE
SOFT-START
AND
VGOFF
DN
DISCHARGE
ENABLE, CONTROL
AND FAULT LOGIC
NEGATIVE
CHARGE PUMP
NEGATIVE
SOFT-START
AND
NAVDD
DISCHARGE
CPGND
EN
FLTB
DGND
INVERTING
REGULATOR
420kHz/2.1MHz
PROGRAMMING
LOGIC &
NV MEMORY
INN
I2C
LXN
MAX25220
ADD
GND
SCL SDA
VPROG
www.maximintegrated.com
Maxim Integrated | 20
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
Functional Diagrams (continued)
MAX25221/B
RREF TEMP
V18
IN
IN
DAC
REG
VCOM
8b ADC FOR
TEMP
COMPENSATION
VCOMN
BST
NAVDD
NEG.
REGULATOR
VCB
PGVDD
FC2+
TFT BOOST
CONTROL
UVLO
HVINP
420kHz/2.1MHz
LXP
FC2-
PGND
POSITIVE
CHARGE PUMP
FC1+
0.9V
TEMP
WARNING,
SHUTDOWN
FC1-
HVINP
AVDD
VGON
REFERENCE
POSITIVE
SOFT-START
AND
VGOFF
DN
DISCHARGE
ENABLE, CONTROL
AND FAULT LOGIC
NEGATIVE
CHARGE PUMP
NEGATIVE
SOFT-START
AND
NAVDD
DISCHARGE
CPGND
EN
FLTB
DGND
INVERTING
REGULATOR
420kHz/2.1MHz
PROGRAMMING
LOGIC &
NV MEMORY
INN
I2C
LXN
MAX25221/B
ADD
GND
SCL SDA
VPROG
www.maximintegrated.com
Maxim Integrated | 21
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
Detailed Description
The MAX25220/MAX25221/MAX25221B are 4-channel TFT-LCD power ICs that provide symmetrical positive AVDD
and negative NAVDD supplies as well as VG and V gate supplies. In addition, a VCOM buffer with output
ON
GOFF
voltage range above and below ground and a temperature-measurement block are integrated in the MAX25221 and
MAX25221B.
The devices contain non-volatile memory so that the values of all outputs can be calibrated for the lifetime of the device.
2
Programming is carried out using the built-in I C interface, which can also be used to read back diagnostic information.
Operation in stand-alone mode is also possible.
The temperature-sensor interface block in the MAX25221 and MAX25221B determines the temperature by measuring
the voltage on the R
pin when a temperature-sensitive component, such as an NTC, is connected to TEMP. The
REF
VCOM output voltage can be adjusted as a function of the measured temperature.
Power-Up state
When power is applied, the MAX25220/1 are in low-quiescent-current mode until the EN pin is taken high. When EN is
taken high (if the device supply voltage on IN exceeds the undervoltage lockout voltage of 2.5V) the 1.8V regulator is
turned on and the device is functional after a delay of 1ms. Subsequent operation depends on the device configuration
and type as follows:
Table 1. DEVICE BEHAVIOR AFTER START-UP
DEVICE
ADD = 0
ADD PIN FLOATING
ADD = V18
MAX25220/ Outputs turned on when start bit in
Outputs turned on
Outputs turned on when start bit in
1
register REG_CTRL is written to 1.
immediately when EN high. register REG_CTRL is written to 1.
Outputs turned on Outputs turned on immediately when EN
immediately when EN high. high.
Outputs turned on immediately when EN
high.
MAX25221B
If the non-volatile memory has been written to previously the stored values are read and the outputs are turned on in the
programmed sequence. If the device has not been programmed previously it powers up with the default voltages of 6.8V
(AVDD), 12V (VG ) and -10V (VG
ON
).
OFF
2
When I C is used, all values can be programmed and the outputs turned on using the start bit in the REG_CTRL register.
The values can subsequently be stored in non-volatile memory using the burn_otp command, if required.
If at any time the internal 1.8V regulator is out of range, the v18oor bit is set in register FAULT2 and the FLTB pin is
2
asserted low, assuming the device is being used in I C mode. No other action is taken unless the V18 voltage is below
its undervoltage lockout level.
Switching Frequency
The switching frequency of the boost and inverting converters and the charge pumps is set using the f
bit in register
SW
CONFIG. When f
is 0, the switching frequency is 2.1MHz. When f
is set to 1, the switching frequency is 420kHz.
SW
SW
The switching frequency can have spread-spectrum applied to improve EMI performance using the en_ss bit in register
CONFIG.
Stand-Alone Operation
Stand-alone operation is used when the device has already been programmed and should start up with the pre-
programmed values when power is applied and the EN pin taken high. In stand-alone mode, leave the ADD pin
unconnected.
2
I C Read-Only Mode
The MAX25221B starts up immediately with the pre-programmed values when power is applied and the EN pin taken
2
high. If the ADD pin is connected to V18 the I C interface is in read-only mode and can only be used to read the device
registers, writing is not possible. The 7-bit I2C address of the device is 0x29 (0x53 when the read bit is added) in this
www.maximintegrated.com
Maxim Integrated | 22
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
mode.
Source Driver Power Supplies
The source-driver power supplies consist of a boost converter with output switch and an inverting buck-boost converter
that generate up to +10.5V maximum and down to -10.5V minimum, respectively, and can deliver up to 200mA on the
positive regulator and -200 mA on the negative regulator. The positive source-driver power supply’s regulation voltage
2
(AVDD) is set by writing the avdd[5:0] value in the AVDD_SET register using the I C interface, and can be programmed
into non-volatile memory. The default AVDD output voltage is 6.8V.
The negative source-driver supply voltage (NAVDD) is automatically tightly regulated to -AVDD within ±34mV. NAVDD
cannot be adjusted independently of AVDD.
The AVDD boost converter is a current-mode converter with two internal switches and internal compensation. The direct
output of the converter is HVINP while AVDD is a switched-output version. The NAVDD converter is a current-mode
converter with one internal switch, an external diode and internal compensation.
Gate-Driver Power Supplies
The positive gate-driver power supply (VG ) is a regulated charge-pump tripler and generates up to +20.2V. Note also
ON
that the maximum output voltage is 3 x AVDD - R
x I
x K, where R
is typically 30Ω and K is a
ONTOTAL
VGON
ONTOTAL
factor 0.75. In cases where a doubler charge pump is sufficient, set the cp_2stage bit and leave pins FC1- and FC1+
unconnected in order to increase efficiency.
The negative gate-driver power supply (VG
) generates a maximum negative voltage of -18.2V and requires external
OFF
diodes and capacitors. The VG
and VG
blocks switch at the same frequency as the AVDD and NAVDD converters.
OFF
ON
Both supplies are capable of output currents up to 15mA, assuming sufficient headroom. The VG
regulation voltages are set by writing the vgon[5:0] and vgoff[5:0] values in the register map using the I C interface, and
can be stored in the non-volatile section of the register map.
and VG
OFF
ON
2
Sequencing
The power-on and power-off sequences are controlled by the seq_set[2:0] bits in the VCOM_L register. The setting
should be written before the sequence is to be executed and should not be changed during the turn-on or turn-off
sequences. The sequence options are as follows:
Table 2. Available Sequences
POWER-OFF (REVERSE-ORDER
SEQUENCE SET BITS
POWER-ON
OF POWER-ON)
2nd 3rd
after t3 after t2 after t1
NOTES
2nd
3rd
4th
4th
Sequence
No.
seq_set2 seq_set1 seq_set0 1st
after t1 after t2 after t3 1st
ms
ms
ms
ms
ms
ms
VG
/
VGON/
ON
1
2
3
4
5
6
0
0
0
0
1
1
0
0
1
1
0
0
0
1
0
1
0
1
AVDD
AVDD
NAVDD VG
NAVDD VG
VG
NAVDD AVDD
NAVDD AVDD
OFF
ON
OFF
ON
VCOM VCOM
VG VG
VCOM VCOM
/
/
OFF
OFF
VG
VG
VG
VG VG
VCOM VCOM
/
/
ON
Default
setting
ON
NAVDD AVDD
NAVDD AVDD
VG
AVDD
AVDD
NAVDD
NAVDD
NAVDD
OFF
OFF
ON
VG VG
VCOM VCOM
/
/
OFF
OFF
VGON
AVDD
VG VGON/
VCOM VCOM
/
ON
NAVDD VG
AVDD
VG
OFF
ON
OFF
ON
AVDD/ AVDD/
VCOM VCOM
VG
VG
NAVDD
NAVDD VG
VG
OFF
OFF
www.maximintegrated.com
Maxim Integrated | 23
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
Table 2. Available Sequences (continued)
AVDD/
NAVDD
VG
VCOM
/
VG
VCOM
/
ON
AVDD/
NAVDD
ON
7
1
1
0
VG
-
-
VG
-
-
OFF
OFF
AVDD/
NAVDD
VG
VCOM
/
VG
VCOM
/
OFF
AVDD/
NAVDD
OFF
8
1
1
1
VG
VGON
ON
The times in the above table are determined by the delayt1, delayt2 and delayt3 settings in the DELAY-VCOM_LSB
register. The fastest power-up is obtained by setting the delays to 0.
The output voltages are not monitored during off sequencing; each output is turned off in turn using the programmed
delays. When the delays are set to zero, outputs are turned off in sequence with 1ms delays .A sequence can be stored
in non-volatile memory by writing to the burn_otp_reg register.
The V18 linear regulator is powered down 200ms after the power-down sequence is complete. After this time, the device
is in shut-down mode and can be restarted by setting the EN input high.
Sequencing Diagram
VGON
tBOOST_SS
AVDD
EN
0V
1ms
VCOM
delayt3
delayt2
delayt1
delayt1
delayt2
delayt3
NAVDD
VGOFF
tINV_SS
Figure 1. Sequencing Example (Sequence 1, Not to Scale)
VCOM Buffer
2
The VCOM output voltage is programmed using I C to a value between -2.49V and +1V. The 9-bit value can also be
stored in non-volatile memory. The most-significant bits of the VCOM voltage setting are in the VCOM25 register while
the least-significant bit is the vcom25_0 bit in the DELAY-DELAYVCOM_LSB register.
The VCOM buffer can output peak currents up to ±120mA. If the VCOM output voltage deviates from the set value by
more than 0.25V, a VCOM fault is detected and flagged with the vcom_flt bit in the FAULT2 register. When this fault is
detected, the VCOM buffer continues to function—it is not automatically disabled. Note that a fault condition can lead to
high power dissipation in the VCOM buffer and could lead to thermal shutdown of the entire device. If the VCOM buffer is
continuously in current limit for more than the time set by tfault[1:0], it is disabled together with the AVDD, NAVDD, VG
H
and VG outputs to avoid damage to the IC. Also in this case the vcom_flt bit is set.
L
The maximum capacitive load on the VCOM output is 10nF. If higher capacitance loads are used, a series resistor should
be employed to maintain stability.
To calculate the value to write to the VCOM25 register use the following equation:
www.maximintegrated.com
Maxim Integrated | 24
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
V
+ 2.49
COM
VCOM25 =
0.00683
The correspondence between the VCOM set value and the VCOM voltage is shown in table 2.
Table 3. VCOM Settings
VCOM25 REGISTER VALUE
VCOM VOLTAGE (V)
0x1FF
0x1FE
...
1
0.9932
...
0x16E
0x16D
0x16C
...
+0.0098
+0.003
-0.0039
...
0x002
0x001
0x000
-2.4763
-2.4832
-2.49
VCOMN Negative Power Supply
A linear regulator is implemented to derive a regulated -3.5V for the VCOM buffer from the NAVDD supply.The npn
transistor connected to the VCB pin acts as the pass transistor of the regulator. The peak output current of the regulator
is the same as the peak negative drive current from the VCOM output, or at least 120mA. The device senses the voltage
at VCOMN and regulates it to -3.5V by driving VCB. The peak drive current for the base of the external npn is at least
5mA.
Limiting the Range of VCOM Voltage
When temperature compensation is not enabled, it is possible to limit the excursion of VCOM to a range between the
values set in the VCOM_MIN and VCOM_MAX registers. If an attempt is made to write a value outside the set range to
2
VCOM25, the VCOM output voltage is not updated and the I C interface issues a NACK.
VCOM Temperature Compensation
The VCOM output voltage can be compensated for temperature changes using a temperature-sensitive component (e.g.
an NTC thermistor) connected to the TEMP input or an internal temperature sensor. Select the sensor to be used with
the int_sensor bit in the CONFIG register (the default configuration is to use the external sensor). The TEMP pin is forced
to 625mV and the current drawn from it is mirrored on the R
pin. The voltage generated due to the resistor on R
REF
REF
is fed to the internal 8-bit ADC, which has a reference voltage of 1.25V. The input to the ADC is therefore as follows:
0.625 × R
RREF
V
=
ADC
R
TEMP
With reference to Figure 2: R
= (R
| | R1) + R2
NTC
TEMP
The highly non-linear NTC characteristic can be modified depending on which temperature (cold, room, or hot)
necessitates the highest resolution. As an example in Figure 2, a reference resistor is connected to R while a
REF
combination of the NTC and two low-TC resistors R1 and R2 are connected to TEMP. In this way, an ADC reading that is
steeper at higher temperatures is obtained, enhancing the resolution of the ADC there. When temperature compensation
is enabled, the value of the voltage on the R
pin is available in the TEMP (0x01) register.
REF
Temperature compensation is enabled by setting the T_comp_en bit in the DELAY-VCOM_LSB register. When
T_comp_en is high, the voltage on the R pin is measured and the VCOM output voltage is updated at a rate of 1Hz.
REF
At start-up, even with temperature compensation enabled, there is a delay before compensation becomes active due to
the time needed to sample the temperature. For this reason, the device always starts up with the VCOM25 voltage value
on VCOM.
www.maximintegrated.com
Maxim Integrated | 25
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
The VCOM value at 25°C is the value written in the VCOM25 register together with the LSB from DELAY-VCOM_LSB
register. This value serves as the reference for all other VCOM values. The 5-bit values in the VCOM_L, and VCOM_H1
registers represent the change in VCOM from the VCOM25 value at the temperature represented by an ADC reading of
VTEMP_L and VTEMP_H1. The value in the VCOM_H2 register represents the positive shift in VCOM from VCOM_H1.
The VCOM_L value represents a negative shift in VCOM while VCOM_H1 and VCOM_H2 represent positive shifts.
NTC Connection Diagram
V18
1.25V
DAC
TEMP
SENSOR
ADC
0.625V
8
TEMP
RREF
T
R1
R2
Figure 2. Possible NTC Connection
Internal Temperature Sensor
The internal temperature sensor senses the junction temperature of the IC which may be significantly different from
the ambient temperature. To use the internal sensor, set the int_sensor bit in the CONFIG register to 1. The internal
temperature sensor has a temperature coefficient of 2mV/°C and a nominal output voltage of 620mV at 25°C.
When the internal temperature sensor is selected, it is connected directly to the ADC input at RREF.
www.maximintegrated.com
Maxim Integrated | 26
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
Temperature Compensation Curve
1V
VCOM (V)
ADC READING
VCOM_H2
VCOM_H1
VCOM_L
-1V
VCOM25
-2V
-2.49V
Figure 3. Temperature Compensation Curve
Fault Handling
2
The reaction to faults is dependent on whether the device is in I C or stand-alone mode.
2
In I C mode, the following faults, if not masked, cause the FLTB pin to assert low: avdd_uv, navdd_uv, vgon_uv,
vgoff_uv, vcom_flt, nv_flt, th_shdn, vin_uvlo, and par_err. The th_warn fault is masked by default and must be explicitly
enabled using the th_warn_mask bit.
2
When the ADD pin is left floating (I C interface not used) the FLTB pin outputs a pulse train of varying duty cycle
depending on the detected fault as shown in Table 4.
Table 4. FLTB Duty Cycle in Stand-Alone Mode
DUTY-CYCLE
FAULT
or VG
75%
VG
fault
OFF
ON
50%
25%
AVDD, NAVDD or HVINP fault
VCOM fault
0% (continuously low)
NV fault or thermal shutdown
The frequency at the FLTB pin is 1kHz when indicating a fault. If multiple faults are present, the highest-priority fault is
indicated. The list above is in order of priority with the highest priority listed last.
Undervoltage Faults on the Source, Gate and VCOM Outputs
When an undervoltage is detected on any of the AVDD, NAVDD, VG , or VG
outputs, all of the outputs are turned
OFF
ON
off and the appropriate fault bit is set in the FAULT1 register. At the same time, the FLTB pin asserts low. Depending on
the setting of the tretry[1:0] bits, the subsequent behavior of the device is as follows:
● tretry = 01, 10 or 11: After 0.95s or 1.9s a retry is performed where all outputs are turned on in the appropriate
sequence. If the fault is still present, the output will be disabled again after tfault[1:0]. A total of three retries are
performed, after which no further retry attempts are performed (the device can be restarted by toggling power or the
EN pin or by using the RESTART command). If tretry = 11 retries continue until the fault is removed and normal
www.maximintegrated.com
Maxim Integrated | 27
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
function can resume.
● tretry = 00: No retry is attempted (the device can be restarted by toggling power or the EN pin or by using the
RESTART command).
If a short-circuit is encountered during start-up, device operation is halted, all outputs are disabled, and the subsequent
behavior depends on the setting of retry[1:0] as described above. The short-circuit checks on VG
enabled 1ms after the pins are enabled.
and VG
are
OFF
ON
During retry, faults are no longer monitored and the fault or faults which caused retry are indicated using the
corresponding fault bits. During retry, the FLTB pin asserts low unless the fault which caused the retry is masked.
Thermal Warning and Shutdown
When the junction temperature reaches 125°C, the thermal warning bit is set. The device takes no further action.
If the device junction temperature reaches 160°C, all outputs are turned off immediately. When the junction temperature
drops by 15°C, the outputs are re-enabled using the stored sequence.
NV Memory
The MAX25220/MAX25221/MAX25221B include five blocks of one-time-programmable memory. The user can store the
block of volatile registers from 0x07 to 0x15 in non-volatile memory which is in turn mapped to register locations 0x17 to
0x25. Note that before the non-volatile memory has been programmed, a read from the locations 0x17 to 0x25 yields the
result 0xFF.
The contents of the non-volatile memory are protected by a single-error correction/double-error detection (SECDED)
redundant code while data transfer from non-volatile memory to registers 0x07 to 0x15 is protected by a parity check. If
the parity check fails, a retry is performed two times. If all three attempts are unsuccessful, the device does not start up,
the nv_flt bit is set, and the FLTB pin is asserted low. If the SECDED check fails, the device does not start up, the nv_flt
bit is set, and the FLTB pin is asserted low.
If there are no errors, the outputs are turned on with the stored values and in the stored sequence.
To store the contents of registers 0x07 to 0x15 to non-volatile memory a voltage source of 8.5V ±2% capable of supplying
2
more than 25mA should be connected to the V
pin. When the V
voltage is stable an I C NV write command
PROG
PROG
can be performed by writing to the burn_otp_reg register. If the NV write is unsuccessful (because the V
voltage
PROG
was out of range or because of a general memory error) the nv_flt bit is set, FLTB pin goes low. After an NV write
command is executed, the nv_flt bit should be checked. If nv_flt is high another NV write can be attempted.
Connect V
to GND if non-volatile memory is not used.
PROG
Ensure that temperature compensation is disabled when programming VCOM.
Auto-Refresh Function
When the refresh bit in register CONFIG is set, the device reads from the non-volatile registers at intervals of 1s and
writes the data into the corresponding volatile registers. This avoids the effect of possible corruption of the volatile
registers. Auto-refresh reads are subject to error correction in the same way as the initial read after device power-up.
When programming the non-volatile memory, the auto-refresh function should be enabled immediately before performing
the burn_otp_reg write. See the section Using the NV Memory in Applications Information.
BURN, REBOOT and RESTART Commands
The BURN and REBOOT commands are used to store the contents of registers 0x07 to 0x15 in non-volatile memory
or to fetch the contents of non-volatile memory and load them into registers 0x07 to 0x15, respectively. The RESTART
command is used to restart the device from a latched-fault mode. When a RESTART command is performed, all fault bits
are cleared.
A BURN command is performed by writing to register address 0x78 (burn_otp_reg).
A REBOOT command is performed by writing to register address 0x79 (reboot_otp_reg).
A RESTART command is performed by writing to register address 0x7A (soft_restart).
www.maximintegrated.com
Maxim Integrated | 28
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
When parity checking is enabled and one of these user commands is sent to the device, the third byte should be such as
to have even parity over the 3 bytes sent.
2
I C Interface
2
The MAX25220/MAX25221/MAX25221B include an I C, 2-wire serial interface consisting of a serial-data line (SDA) and
a serial-clock line (SCL). SDA and SCL facilitate communication between the IC and the master at clock rates up to
400kHz. The master, typically a microcontroller, generates SCL and initiates data transfer on the bus.
The Slave ID of the MAX25220/MAX25221/MAX25221B depends on the connection of the ADD pin according to Table
4.
A master device communicates with the MAX25220/MAX25221/MAX25221B by transmitting the correct Slave ID with
appended R/W bit, followed by the register address and data word (for a write transaction only). Each transmit sequence
is framed by a START (S) or Repeated START (Sr) condition, and a STOP (P) condition. Each word transmitted over the
bus is 8 bits long and is always followed by an acknowledge clock pulse.
The IC's SDA line operates as both an input and an open-drain output. A pullup resistor greater than 1kΩ is required on
the SDA bus. In general, the resistor should be selected as a function of bus capacitance such that the rise time on the
bus is not greater than 120ns. The IC's SCL line operates as an input only. A pullup resistor greater than 1kΩ is required
on SCL if there are multiple masters on the bus, or if the master in a single-master system has an open-drain SCL output.
In general, for the SCL-line resistor selection, the same recommendations as for SDA apply. Series resistors in line with
SDA and SCL are optional. The SCL and SDA inputs suppress noise spikes to assure proper device operation even on
a noisy bus.
2
I C Slave Addresses
2
Table 5. I C Slave Addresses
DEVICE ADDRESS
WRITE
ADDRESS
READ
ADDRESS
ADD PIN CONNECTION
A6
0
A5
1
A4
0
A3
0
A2
0
A1
0
A0
1
GND
V18
0x42
0x43
0x53
0
1
0
1
0
0
1
0x52*
* On the MAX25221B writing to the device is not possible when ADD is connected to V18.
Parity Checking
Even parity checking for write transactions can be enabled by setting the par_en bit in REG_CTRL to 1. The parity bit is
the most-significant bit of the register address byte and should be set to attain even parity. The parity check is performed
over all 3 bytes received by the device: the slave address, the register address, and the data payload. Burst-mode write
2
is not supported when parity checking is enabled; a complete I C transaction is needed to write to each single register.
2
When a parity bit error is detected the par_err bit is set, the I C interface issues a NACK and no write is performed.
When writing any of the BURN, REBOOT, and RESTART commands, parity must be adjusted by changing the third or
payload byte; the command byte must not be changed.
www.maximintegrated.com
Maxim Integrated | 29
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
Register Map
MAX25220/MAX25221/MAX25221B
ADDRESS
NAME
MSB
LSB
USER REGISTERS
0x00
0x01
0x02
DEVICE[7:0]
TEMP[7:0]
–
–
dev_id[5:0]
temp[7:0]
REG_CTRL[7:0]
FLTMASK1[7:0]
par_en
–
start
–
–
–
–
rev_id[2:0]
–
avdd_uv
_mask
navdd_u
v_mask
vgon_uv
_mask
vgoff_uv
_mask
0x03
0x04
–
–
–
par_err_ vin_uvlo hvinp_uv
vcom_flt th_warn_
_mask
FLTMASK2[7:0]
–
–
mask
avdd_uv
par_err
refresh
_mask
_mask
mask
navdd_u
v
0x05
0x06
0x07
FAULT1[7:0]
FAULT2[7:0]
CONFIG[7:0]
–
–
vgon_uv
nv_flt
–
vgoff_uv
th_warn
v18oor
vin_uvlo hvinp_uv th_shdn
en_ss fSW
delayt2[1:0]
vcom25[7:0]
vcom_flt
int_sens
or
tretry[1:0]
delayt3[1:0]
tfault[1:0]
DELAY-
VCOM_LSB[7:0]
T_comp_ vcom25_
en
0x08
delayt1[1:0]
0
0x09
0x0A
0x0B
0x0C
0x0D
0x0E
0x0F
0x10
0x11
0x12
0x13
VCOM25[7:0]
VCOM_L[7:0]
seq_set[2:0]
vcom_l[4:0]
VCOM_H1[7:0]
VCOM_H2[7:0]
VTEMP25[7:0]
VTEMP_L[7:0]
VTEMP_H1[7:0]
VTEMP_H2[7:0]
VCOM_MIN[7:0]
VCOM_MAX[7:0]
AVDD_SET[7:0]
–
–
–
–
–
–
vcom_h1[4:0]
vcom_h2[4:0]
vtemp25[7:0]
vtemp_l[7:0]
vtemp_h1[7:0]
vtemp_h2[7:0]
vcom_min[7:0]
vcom_max[7:0]
–
–
–
–
avdd[5:0]
cp_2stag
e
0x14
0x15
0x17
VGON[7:0]
vgon[5:0]
vgoff[5:0]
VGOFF[7:0]
–
nv_int_s nv_refres nv_en_s
ensor
NV_CONFIG[7:0]
nv_fSW
nv_retry[1:0]
nv_tfault[1:0]
h
s
NV_DELAY-
VCOM_LSB[7:0]
nv_T_co nv_vcom
0x18
nv_delayt1[1:0]
nv_delayt2[1:0]
nv_delayt3[1:0]
mp_en
25_0
0x19
0x1A
0x1B
0x1C
0x1D
0x1E
0x1F
NV_VCOM25[7:0]
NV_VCOM_L[7:0]
NV_VCOM_H1[7:0]
NV_VCOM_H2[7:0]
NV_VTEMP25[7:0]
NV_VTEMP_L[7:0]
NV_TEMP_H1[7:0]
nv_vcom25[7:0]
nv_seq_set[2:0]
nv_vcom_l[4:0]
–
–
–
–
–
nv_vcom_h1[4:0]
nv_vcom_h2[4:0]
–
nv_vtemp25[7:0]
nv_vtemp_l[7:0]
nv_vtemp_h1[7:0]
www.maximintegrated.com
Maxim Integrated | 30
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
ADDRESS
0x20
NAME
MSB
LSB
NV_TEMP_H2[7:0]
NV_VCOM_MIN[7:0]
NV_VCOM_MAX[7:0]
NV_AVDD_SET[7:0]
nv_vtemp_h2[7:0]
0x21
nv_vcom_min[7:0]
0x22
nv_vcom_max[7:0]
0x23
–
–
–
–
nv_avdd[5:0]
nv_vgon[5:0]
nv_vgoff[5:0]
nv_cp_2
stage
0x24
0x25
NV_VGON[7:0]
NV_VGOFF[7:0]
–
USER COMMANDS
0x78
0x79
0x7A
burn_otp_reg[7:0]
burn_otp[7:0]
reboot_otp_reg[7:0]
soft_restart[7:0]
reboot_otp[7:0]
soft_restart[7:0]
Register Details
DEVICE (0x00)
BIT
Field
7
–
–
6
–
–
5
4
3
2
1
0
0
0
dev_id[5:0]
Reset
Access
Type
–
–
Read Only
BITFIELD
BITS
DESCRIPTION
dev_id
5:0
Device ID. Reads 0x20/21
TEMP (0x01)
BIT
7
6
5
4
3
2
1
Field
temp[7:0]
0x0
Reset
Access
Type
Read Only
BITFIELD
BITS
DESCRIPTION
pin.
temp
7:0
Voltage reading from R
REF
REG_CTRL (0x02)
BIT
7
6
5
–
–
4
–
–
3
–
–
2
1
Field
par_en
0x0
start
0x0
rev_id[2:0]
0x1
Reset
Access
Type
Write, Read Write, Read
–
–
–
Read Only
BITFIELD
BITS
DESCRIPTION
Parity enable bit. When 1 this bit enables parity checking on write transactions
to the device.
par_en
7
www.maximintegrated.com
Maxim Integrated | 31
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
BITFIELD
BITS
DESCRIPTION
Enable bit. When this bit is set to 1 the turn-on sequence set using the
seq_set bits is executed. The default value of this bit is 0 except in the
MAX25221B where it is 1.
start
6
rev_id
2:0
Revision ID. Reads 0x1.
FLTMASK1 (0x03)
BIT
7
–
–
–
6
5
–
–
–
4
3
–
–
–
2
1
–
–
–
0
avdd_uv_m
ask
navdd_uv_
mask
vgon_uv_m
ask
vgoff_uv_m
ask
Field
Reset
0x0
0x0
0x0
0x0
Access
Type
Write, Read
Write, Read
Write, Read
Write, Read
BITFIELD
BITS
DESCRIPTION
avdd_uv_mask
6
When 1 this bit prevents an undervoltage on AVDD from asserting FLTB low.
When 1 this bit prevents an undervoltage on NAVDD from asserting FLTB
low.
navdd_uv_mask
vgon_uv_mask
vgoff_uv_mask
4
2
0
When 1 this bit prevents an undervoltage on VGON from asserting FLTB low.
When 1 this bit prevents an undervoltage on VGOFF from asserting FLTB
low.
FLTMASK2 (0x04)
BIT
7
–
–
–
6
5
4
3
–
–
–
2
–
–
–
1
0
par_err_ma vin_uvlo_m hvinp_uv_m
vcom_flt_m th_warn_ma
Field
sk
ask
ask
ask
sk
Reset
0x0
0x0
0x0
0x0
0x1
Access
Type
Write, Read Write, Read Write, Read
Write, Read Write, Read
BITFIELD
par_err_mask
BITS
DESCRIPTION
6
5
When 1 prevents parity errors from asserting the FLTB pin.
vin_uvlo_mask
When 1 this bit prevents an undervoltage on IN from asserting the FLTB pin.
Mask bit for hvinp_uv diagnostic. When 1 an undervoltage on HVINP does not
cause FLTB to assert.
hvinp_uv_mask
vcom_flt_mask
th_warn_mask
4
1
0
When 1 this bit prevents a fault on VCOM from asserting FLTB low.
When 1 this bit prevents an overtemperature warning from asserting FLTB
low.
FAULT1 (0x05)
BIT
Field
7
–
–
6
5
–
–
4
3
–
–
2
1
–
–
0
avdd_uv
0x0
navdd_uv
0x0
vgon_uv
0x0
vgoff_uv
0x0
Reset
Access
Type
Read
Clears All
Read
Clears All
Read
Clears All
Read
Clears All
–
–
–
–
BITFIELD
BITS
DESCRIPTION
avdd_uv
6
When 1 this bit indicates an undervoltage on AVDD.
www.maximintegrated.com
Maxim Integrated | 32
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
BITFIELD
navdd_uv
BITS
DESCRIPTION
4
2
0
When 1 this bit indicates an undervoltage on NAVDD.
vgon_uv
vgoff_uv
When 1 this bit indicates an undervoltage on VG
When 1 this bit indicates an undervoltage on VG
.
ON
.
OFF
FAULT2 (0x06)
BIT
Field
7
6
5
4
3
2
1
0
v18oor
0x0
par_err
0x0
vin_uvlo
0x0
hvinp_uv
0x0
th_shdn
0x0
nv_flt
0x0
vcom_flt
0x0
th_warn
0x0
Reset
Access
Type
Read
Clears All
Read
Clears All
Read
Clears All
Read
Clears All
Read
Clears All
Read
Clears All
Read
Clears All
Read
Clears All
BITFIELD
v18oor
BITS
DESCRIPTION
Indicates that the 1.8V output is out of range, either above its overvoltage
level or below its undervoltage level.
7
6
2
par_err
Indicates that a parity error was detected on an I C transaction.
Indicates an undervoltage condition on the IN pin. When this happens the
device turns off all outputs and waits for IN to return above the IN UVLO level,
after which the outputs are re-enabled in the programmed sequence.
vin_uvlo
5
hvinp_uv
th_shdn
4
3
When 1 this bit indicates an undervoltage on the boost output, HVINP.
When 1 this bit indicates an overtemperature shutdown.
Non-volatile memory failure - unsuccessful transfer of the contents of NV
memory to working memory or more than one error detected.
nv_flt
2
When 1 indicates a fault on the VCOM output either due to it being 0.25V
away from its set value (unfiltered) or because the VCOM buffer was in
vcom_flt
th_warn
1
0
current limit for a time t
.
fault
When 1 this bit indicates a thermal warning.
CONFIG (0x07)
BIT
7
6
5
4
3
2
1
0
Field
int_sensor
0x0
refresh
0x0
en_ss
0x0
fSW
0x0
tretry[1:0]
0x1
tfault[1:0]
0x0
Reset
Access
Type
Write, Read Write, Read Write, Read Write, Read
Write, Read
Write, Read
BITFIELD
BITS
DESCRIPTION
DECODE
Set this bit to 1 to use the internal
temperature sensor.
int_sensor
refresh
7
When this bit is 1 the contents of the NV
registers are automatically copied to the
volatile registers every second.
0x0: Refresh disabled.
0x1: Refresh enabled.
6
Enable spread-spectrum by setting this bit to
1.
en_ss
fSW
5
4
0x0: 2.1MHz
0x1: 420kHz
Sets switching frequency.
0x0: Retry disabled
0x1: Retry after 0.95s, total 3 retries.
0x2: Retry after 1.9s, total 3 retries.
0x3: Retry after 1.9s
tretry
3:2
Sets retry time after a fault.
www.maximintegrated.com
Maxim Integrated | 33
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
BITFIELD
BITS
DESCRIPTION
DECODE
0x0: 15ms
0x1: 30ms
0x2: 60ms
0x3: 90ms
tfault
1:0
Sets fault delay time.
DELAY-VCOM_LSB (0x08)
BIT
Field
7
6
5
4
3
2
1
0
delayt1[1:0]
0x2
delayt2[1:0]
0x2
delayt3[1:0]
0x2
T_comp_en
0x0
vcom25_0
0x0
Reset
Access
Type
Write, Read
Write, Read
Write, Read
Write, Read Write, Read
BITFIELD
BITS
DESCRIPTION
Set delay t1 in the start-up sequence. Choose between 0, 5ms, 10ms and
15ms.
delayt1
delayt2
delayt3
7:6
Set delay t2 in the start-up sequence. Choose between 0, 5ms, 10ms and
15ms.
5:4
3:2
Set delay t3 in the start-up sequence. Choose between 0, 5ms, 10ms and
15ms.
When 1 this bit enables temperature compensation of the output of the VCOM
amplifier.
T_comp_en
vcom25_0
1
0
LSB of VCOM setting at 25°C.
VCOM25 (0x09)
BIT
Field
7
6
5
4
3
2
1
0
vcom25[7:0]
0x0
Reset
Access
Type
Write, Read
BITFIELD
BITS
DESCRIPTION
vcom25
7:0
VCOM setting at 25°C.
VCOM_L (0x0A)
BIT
Field
7
6
5
4
3
2
1
0
seq_set[2:0]
0x2
vcom_l[4:0]
0x00
Reset
Access
Type
Write, Read
Write, Read
BITFIELD
BITS
DESCRIPTION
DECODE
0x0: Sequence 1.
0x1: Sequence 2.
0x2: Sequence 3.
0x3: Sequence 4.
0x4: Sequence 5.
0x5: Sequence 6.
0x6: Sequence 7.
0x7: Sequence 8.
seq_set
7:5
Sequence selection bits.
www.maximintegrated.com
Maxim Integrated | 34
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
BITFIELD
BITS
DESCRIPTION
DECODE
Delta VCOM at at the temperature
corresponding to VTEMP_L. This value sets
the difference between the VCOM value at
25°C and that at VTEMP_L.
vcom_l
4:0
VCOM_H1 (0x0B)
BIT
Field
7
–
–
6
–
–
5
–
–
4
3
2
1
0
vcom_h1[4:0]
0x00
Reset
Access
Type
–
–
–
Write, Read
BITFIELD
BITS
DESCRIPTION
Delta VCOM at VTEMP_H1. This value sets the difference between the
VCOM value at 25°C and that at VTEMP_H1.
vcom_h1
4:0
VCOM_H2 (0x0C)
BIT
Field
7
–
–
6
–
–
5
–
–
4
3
2
1
0
vcom_h2[4:0]
0x0
Reset
Access
Type
–
–
–
Write, Read
BITFIELD
BITS
DESCRIPTION
Delta VCOM at VTEMP_H2. This value sets the difference between the
VCOM value at VTEMP_H1 and that at VTEMP_H2.
vcom_h2
4:0
VTEMP25 (0x0D)
BIT
Field
7
6
5
4
3
2
1
0
vtemp25[7:0]
0x0
Reset
Access
Type
Write, Read
BITFIELD
BITS
DESCRIPTION
vtemp25
7:0
Voltage at TEMP pin at 25°C.
VTEMP_L (0x0E)
BIT
Field
7
6
5
4
3
2
1
0
vtemp_l[7:0]
0x0
Reset
Access
Type
Write, Read
BITFIELD
BITS
DESCRIPTION
Voltage at TEMP pin corresponding to low-temperature breakpoint in VCOM
compensation curve.
vtemp_l
7:0
www.maximintegrated.com
Maxim Integrated | 35
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
VTEMP_H1 (0x0F)
BIT
Field
7
7
7
6
5
4
3
2
1
0
vtemp_h1[7:0]
Reset
0x0
Access
Type
Write, Read
BITFIELD
BITS
DESCRIPTION
Voltage at TEMP pin corresponding to first high-temperature breakpoint in
VCOM compensation curve.
vtemp_h1
7:0
VTEMP_H2 (0x10)
BIT
Field
6
5
4
3
2
1
0
vtemp_h2[7:0]
Reset
0x0
Access
Type
Write, Read
BITFIELD
BITS
DESCRIPTION
Voltage at TEMP pin corresponding to second high-temperature breakpoint in
VCOM compensation curve.
vtemp_h2
7:0
VCOM_MIN (0x11)
BIT
Field
6
5
5
5
4
3
2
1
1
1
0
0
0
vcom_min[7:0]
Reset
0x0
Access
Type
Write, Read
BITFIELD
BITS
DESCRIPTION
vcom_min
7:0
Lower limit for VCOM setting.
VCOM_MAX (0x12)
BIT
Field
7
6
4
3
2
vcom_max[7:0]
Reset
0xFF
Access
Type
Write, Read
BITFIELD
BITS
DESCRIPTION
vcom_max
7:0
Upper limit for VCOM setting.
AVDD_SET (0x13)
BIT
Field
7
–
–
6
–
–
4
3
2
avdd[5:0]
0x1A
Reset
Access
Type
–
–
Write, Read
www.maximintegrated.com
Maxim Integrated | 36
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
BITFIELD
BITS
DESCRIPTION
DECODE
0x0: 4.2
0x1: 4.3
0x2: 4.4
0x3: 4.5
0x4: 4.6
0x5: 4.7
0x6: 4.8
0x7: 4.9
0x8: 5
0x9: 5.1
0xA: 5.2
0xB: 5.3
0xC: 5.4
0xD: 5.5
0xE: 5.6
0xF: 5.7
0x10: 5.8
0x11: 5.9
0x12: 6
0x13: 6.1
0x14: 6.2
0x15: 6.3
0x16: 6.4
0x17: 6.5
0x18: 6.6
0x19: 6.7
0x1A: 6.8
0x1B: 6.9
0x1C: 7V
0x1D: 7.1
0x1E: 7.2
0x1F: 7.3
0x20: 7.4
0x21: 7.5
0x22: 7.6
0x23: 7.7
0x24: 7.8
0x25: 7.9
0x26: 8
avdd
5:0
Sets AVDD and NAVDD voltages.
0x27: 8.1
0x28: 8.2
0x29: 8.3
0x2A: 8.4
0x2B: 8.5
0x2C: 8.6
0x2D: 8.7
0x2E: 8.8
0x2F: 8.9
0x30: 9
0x31: 9.1
0x32: 9.2
0x33: 9.3
0x34: 9.4
0x35: 9.5
0x36: 9.6
0x37: 9.7
0x38: 9.8
www.maximintegrated.com
Maxim Integrated | 37
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
BITFIELD
BITS
DESCRIPTION
DECODE
0x39: 9.9
0x3A: 10
0x3B: 10.1
0x3C: 10.2
0x3D: 10.3
0x3E: 10.4
0x3F: 10.5
VGON (0x14)
BIT
7
–
–
6
5
4
3
2
1
0
Field
cp_2stage
0x0
vgon[5:0]
0x16
Reset
Access
Type
–
Write, Read
Write, Read
BITFIELD
BITS
DESCRIPTION
DECODE
Set this bit to 1 when using a two-stage
charge-pump.
cp_2stage
6
www.maximintegrated.com
Maxim Integrated | 38
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
BITFIELD
BITS
DESCRIPTION
DECODE
0x0: 7.6
0x1: 7.8
0x2: 8
0x3: 8.2
0x4: 8.4
0x5: 8.6
0x6: 8.8
0x7: 9
0x8: 9.2
0x9: 9.4
0xA: 9.6
0xB: 9.8
0xC: 10
0xD: 10.2
0xE: 10.4
0xF: 10.6
0x10: 10.8
0x11: 11
0x12: 11.2
0x13: 11.4
0x14: 11.6
0x15: 11.8
0x16: 12
0x17: 12.2
0x18: 12.4
0x19: 12.6
0x1A: 12.8
0x1B: 13
0x1C: 13.2
0x1D: 13.4
0x1E: 13.6
0x1F: 13.8
0x20: 14
vgon
5:0
Sets VG
voltage.
ON
0x21: 14.2
0x22: 14.4
0x23: 14.6
0x24: 14.8
0x25: 15
0x26: 15.2
0x27: 15.4
0x28: 15.6
0x29: 15.8
0x2A: 16
0x2B: 16.2
0x2C: 16.4
0x2D: 16.6
0x2E: 16.8
0x2F: 17
0x30: 17.2
0x31: 17.4
0x32: 17.6
0x33: 17.8
0x34: 18
0x35: 18.2
0x36: 18.4
0x37: 18.6
0x38: 18.8
www.maximintegrated.com
Maxim Integrated | 39
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
BITFIELD
BITS
DESCRIPTION
DECODE
0x39: 19
0x3A: 19.2
0x3B: 19.4
0x3C: 19.6
0x3D: 19.8
0x3E: 20
0x3F: 20.2
VGOFF (0x15)
BIT
Field
7
–
–
6
–
–
5
4
3
2
1
0
vgoff[5:0]
0x16
Reset
Access
Type
–
–
Write, Read
www.maximintegrated.com
Maxim Integrated | 40
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
BITFIELD
BITS
DESCRIPTION
DECODE
0x0: -5.6
0x1: -5.8
0x2: -6
0x3: -6.2
0x4: -6.4
0x5: -6.6
0x6: -6.8
0x7: -7
0x8: -7.2
0x9: -7.4
0xA: -7.6
0xB: -7.8
0xC: -8
0xD: -8.2
0xE: -8.4
0xF: -8.6
0x10: -8.8
0x11: -9
0x12: -9.2
0x13: -9.4
0x14: -9.6
0x15: -9.8
0x16: -10
0x17: -10.2
0x18: -10.4
0x19: -10.6
0x1A: -10.8
0x1B: -11
0x1C: -11.2
0x1D: -11.4
0x1E: -11.6
0x1F: -11.8
0x20: -12
0x21: -12.2
0x22: -12.4
0x23: -12.6
0x24: -12.8
0x25: -13
0x26: -13.2
0x27: -13.4
0x28: -13.6
0x29: -13.8
0x2A: -14
0x2B: -14.2
0x2C: -14.4
0x2D: -14.6
0x2E: -14.8
0x2F: -15
0x30: -15.2
0x31: -15.4
0x32: -15.6
0x33: -15.8
0x34: -16
0x35: -16.2
0x36: -16.4
0x37: -16.6
0x38: -16.8
vgoff
5:0
Sets VG
voltage.
OFF
www.maximintegrated.com
Maxim Integrated | 41
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
BITFIELD
BITS
DESCRIPTION
DECODE
0x39: -17
0x3A: -17.2
0x3B: -17.4
0x3C: -17.6
0x3D: -17.8
0x3E: -18
0x3F: -18.2
NV_CONFIG (0x17)
Non-volatile configuration register
BIT
7
6
5
4
3
2
1
0
nv_int_sens
or
Field
nv_refresh
nv_en_ss
nv_fSW
nv_retry[1:0]
nv_tfault[1:0]
Read Only
Reset
Access
Type
Read Only
Read Only
Read Only
Read Only
Read Only
BITFIELD
BITS
DESCRIPTION
DECODE
nv_int_senso
r
When this bit is 1 the internal temperature
sensor is used.
7
When this bit is 1 the contents of the NV
registers are automatically copied to the
volatile registers every second.
nv_refresh
6
When this bit is 1 spread-spectrum is
enabled.
nv_en_ss
nv_fSW
5
4
0x0: 2.2MHz
0x1: 440kHz
Sets switching frequency.
nv_retry
nv_tfault
3:2
1:0
Sets retry time after a fault.
Sets retry time after a fault.
NV_DELAY-VCOM_LSB (0x18)
BIT
7
6
5
4
3
2
1
0
nv_T_comp nv_vcom25
Field
nv_delayt1[1:0]
nv_delayt2[1:0]
nv_delayt3[1:0]
_en
0x0
_0
Reset
Access
Type
Read Only
Read Only
Read Only
Read Only
Read Only
BITFIELD
BITS
DESCRIPTION
Set delay t1 in the start-up sequence. Choose between 0, 5ms, 10ms and
15ms.
nv_delayt1
7:6
Set delay t2 in the start-up sequence. Choose between 0, 5ms, 10ms and
15ms.
nv_delayt2
5:4
3:2
1
Set delay t3 in the start-up sequence. Choose between 0, 5ms, 10ms and
15ms.
nv_delayt3
When 1 this bit enables temperature compensation of output of the VCOM
amplifier.
nv_T_comp_en
nv_vcom25_0
When 1 this bit enables temperature compensation of output of the VCOM
amplifier.
0
www.maximintegrated.com
Maxim Integrated | 42
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
NV_VCOM25 (0x19)
BIT
Field
7
6
5
4
3
2
1
0
nv_vcom25[7:0]
Reset
Access
Type
Read Only
BITFIELD
nv_vcom25
BITS
DESCRIPTION
7:0
VCOM setting at 25°C.
NV_VCOM_L (0x1A)
BIT
Field
7
6
5
4
3
2
1
0
nv_seq_set[2:0]
nv_vcom_l[4:0]
Reset
Access
Type
Read Only
Read Only
BITFIELD
BITS
DESCRIPTION
nv_seq_set
nv_vcom_l
7:5
Sequence selection bits.
Delta VCOM at at the temperature corresponding to VTEMP_L. This value
sets the difference between the VCOM value at 25°C and that at VTEMP_L.
4:0
NV_VCOM_H1 (0x1B)
BIT
Field
7
–
–
6
–
–
5
–
–
4
3
2
1
0
nv_vcom_h1[4:0]
Reset
Access
Type
–
–
–
Read Only
BITFIELD
nv_vcom_h1
BITS
DESCRIPTION
Delta VCOM at VTEMP_H1. This value sets the difference between the
VCOM value at 25°C and that at VTEMP_H1.
4:0
NV_VCOM_H2 (0x1C)
BIT
Field
7
–
–
6
–
–
5
–
–
4
3
2
1
0
nv_vcom_h2[4:0]
Reset
Access
Type
–
–
–
Read Only
BITFIELD
nv_vcom_h2
BITS
DESCRIPTION
Delta VCOM at VTEMP_H2. This value sets the difference between the
VCOM value at VTEMP_H1 and that at VTEMP_H2.
4:0
www.maximintegrated.com
Maxim Integrated | 43
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
NV_VTEMP25 (0x1D)
BIT
Field
7
6
5
4
3
2
1
0
nv_vtemp25[7:0]
Reset
Access
Type
Read Only
BITFIELD
nv_vtemp25
BITS
DESCRIPTION
7:0
Voltage at TEMP pin at 25°C.
NV_VTEMP_L (0x1E)
BIT
Field
7
6
5
4
3
2
1
0
nv_vtemp_l[7:0]
Reset
Access
Type
Read Only
BITFIELD
nv_vtemp_l
BITS
DESCRIPTION
Voltage at TEMP pin corresponding to low-temperature breakpoint in VCOM
compensation curve.
7:0
NV_TEMP_H1 (0x1F)
BIT
Field
7
6
5
4
3
2
1
0
nv_vtemp_h1[7:0]
Reset
Access
Type
Read Only
BITFIELD
nv_vtemp_h1
BITS
DESCRIPTION
Voltage at TEMP pin corresponding to first high-temperature breakpoint in
VCOM compensation curve.
7:0
NV_TEMP_H2 (0x20)
BIT
Field
7
6
5
4
3
2
1
0
nv_vtemp_h2[7:0]
Reset
Access
Type
Read Only
BITFIELD
nv_vtemp_h2
BITS
DESCRIPTION
Voltage at TEMP pin corresponding to second high-temperature breakpoint in
VCOM compensation curve.
7:0
www.maximintegrated.com
Maxim Integrated | 44
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
NV_VCOM_MIN (0x21)
BIT
Field
7
6
5
5
5
5
4
3
2
1
1
1
0
0
0
0
nv_vcom_min[7:0]
Reset
Access
Type
Read Only
BITFIELD
nv_vcom_min
BITS
DESCRIPTION
7:0
Lower limit for VCOM setting.
NV_VCOM_MAX (0x22)
BIT
Field
7
6
4
3
2
nv_vcom_max[7:0]
Reset
Access
Type
Read Only
BITFIELD
nv_vcom_max
BITS
DESCRIPTION
7:0
Upper limit for VCOM setting.
NV_AVDD_SET (0x23)
BIT
Field
7
–
–
6
–
–
4
3
2
nv_avdd[5:0]
Reset
Access
Type
–
–
Read Only
BITFIELD
BITS
DESCRIPTION
nv_avdd
5:0
Sets AVDD and NAVDD voltages. See table for register 0x13.
NV_VGON (0x24)
BIT
7
–
–
–
6
4
3
2
1
nv_cp_2sta
ge
Field
nv_vgon[5:0]
Read Only
Reset
Access
Type
Read Only
BITFIELD
nv_cp_2stage
nv_vgon
BITS
6
DESCRIPTION
When this bit is set to 1 a two-stage charge-pump is used.
Sets VG voltage. See table for register 0x14.
5:0
ON
NV_VGOFF (0x25)
BIT
Field
7
–
–
6
–
–
5
4
3
2
1
0
nv_vgoff[5:0]
Read Only
Reset
Access
Type
–
–
www.maximintegrated.com
Maxim Integrated | 45
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
BITFIELD
nv_vgoff
BITS
5:0
DESCRIPTION
Sets VGOFF voltage. See table for register 0x15.
burn_otp_reg (0x78)
BIT
Field
7
6
5
5
5
4
3
2
1
0
burn_otp[7:0]
0x0
Reset
Access
Type
Write Only
BITFIELD
burn_otp
BITS
DESCRIPTION
Command to copy the contents of registers 0x07-0x15 to the non-volatile
registers 0x17-0x25.
7:0
reboot_otp_reg (0x79)
BIT
Field
7
6
4
3
2
1
0
reboot_otp[7:0]
Reset
Access
Type
Write Only
BITFIELD
reboot_otp
BITS
DESCRIPTION
Command to copy the contents of the non-volatile registers 0x17-0x15 to the
working registers 0x17-0x25.
7:0
soft_restart (0x7A)
BIT
Field
7
6
4
3
2
1
0
soft_restart[7:0]
0x00
Reset
Access
Type
Write Only
BITFIELD
BITS
DESCRIPTION
Command used to re-start the device from a latched fault mode. All faults are
cleared when this command is executed.
soft_restart
7:0
www.maximintegrated.com
Maxim Integrated | 46
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
Applications Information
Boost Converter
Boost Converter Inductor Selection
Three key inductor parameters must be specified for operation with the device: Inductance value (L), inductor saturation
current (I ), and DC resistance (R ). To determine the inductance value, first select the ratio of inductor peak-to-
SAT
DC
peak ripple current to average output current (LIR). Higher LIR values mean higher RMS inductor current and therefore
2
higher I R losses. To achieve a lower LIR value, a high-valued inductor, which may be physically larger, must be used. A
good compromise between size and loss is to select a 30% to 60% peak-to-peak ripple current to average-current ratio
(LIR from 0.3 to 0.6). If extremely thin high-resistance inductors are used, as is common for LCD-panel applications, the
best LIR may lie between 0.5 and 1.0. The value of the inductor is determined below.
V
× D
IN
L =
LIR × I × f
IN SW
using:
V
× I
OUT OUT
I
=
IN
η × V
IN
V
IN
D = 1 −
V
OUT
where V is the input voltage, V
is the output voltage, I
is the output current, I is the calculated average boost
OUT IN
IN
OUT
input current, η is the efficiency of the boost converter, D is the duty cycle, and f
is either 420kHz or 2.1MHz (the
SW
selected switching frequency of the boost converter). The efficiency of the boost converter can be estimated from the
Typical Operating Characteristics and accounts for losses in the internal switch, inductor, and capacitors.
The inductor’s saturation rating must exceed the maximum current-limit of 2.3A.
Boost Output Filter Capacitor Selection
The primary criterion for selecting the output filter capacitor is low effective series resistance (ESR). The product of the
peak inductor current and the output filter capacitor’s ESR determine the amplitude of the high-frequency ripple seen
on the output voltage. For stability, the boost output-filter capacitor should have a value of 10μF or greater when using
2.1MHz switching.
To avoid a large drop on HVINP when AVDD is enabled, the capacitance on the HVINP node should be at least three
times larger than that on AVDD.
Boost Input Filter Capacitor
Sufficient input capacitance must be used to avoid input voltage drop when transients are encountered on the AVDD or
NAVDD outputs and when the AVDD switch is closed. If the IN voltage drops below 2.57V, the device is likely to reset so
input capacitance must prevent this. The total value of capacitance depends on the expected transients and the series
resistance in the IN connection. A good starting point is a total input capacitance of 2 x 22μF ceramic capacitors in parallel
with 2 x 10μF ceramic capacitors. Depending on the particular application circumstances more or less capacitance may
be needed.
Input capacitance requirements are significantly relaxed when an input voltage of 5V is used.
Setting the AVDD Voltage
The AVDD output voltage is set by writing a 6-bit value to the AVDD_SET register.
The NAVDD converter outputs a negative voltage whose absolute value is the same as AVDD.
NAVDD Inverting Regulator
www.maximintegrated.com
Maxim Integrated | 47
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
NAVDD Regulator Inductor Selection
The inductor value for the NEG regulator can be selected using the formula below.
V
× (1 − D)
NAVDD
L =
LIR × I
× f
NAVDD SW
where V
is the output voltage, I
the output current, LIR the desired inductor ripple ratio, and f
the
SW
NAVDD
NAVDD
switching frequency.
Calculate the duty-cycle D using:
V
NAVDD
D =
V
+ V
IN
NAVDD
The inductor's saturation current rating must exceed the maximum current-limit of 2.25A.
NAVDD External Diode Selection
Select a diode with a peak current rating of at least the LXN current limit (I
) for use with the NAVDD output.
LIMNH
The diode breakdown-voltage rating should exceed the sum of the maximum INN voltage and the absolute value of the
NAVDD voltage. A Schottky diode improves the overall efficiency of the converter but should be selected to have low
leakage at the maximum operating temperature.
NAVDD Output Capacitor Selection
The primary criterion for selecting the output filter capacitor is low ESR and capacitance value, as the NAVDD capacitor
provides the load current when the internal switch is on. The voltage ripple on the NAVDD output has two components:
1. Ripple to due ESR which is the product of the peak inductor current and the output filter capacitor’s ESR
2. Ripple due to bulk capacitance that can be determined as follows.
D
I
×
NAVDD
f
SW
ΔV
=
BULK
C
NAVDD
For stability, the NAVDD output capacitor should have a value of 10μF or greater when using 2.1MHz switching
frequency.
Setting the VG
and VG
Output Voltages
OFF
ON
The internal positive charge pump can output a voltage approximately three times AVDD. If a voltage of twice the HVINP
voltage is sufficient leave the FC1+ and FC1- pins unconnected and set the cp_2stage bit.
For V
the VG
, the number of charge-pump stages should be chosen to ensure sufficient output voltage while maintaining
voltage within its permitted operating range.
GOFF
OFF
The VG
The VG
output voltage is set by writing a 6-bit value to the vgon[5:0] field in the VG
register.
ON
ON
voltage is set by writing a 6-bit value to the vgoff[5:0] field in the VG
register.
OFF
OFF
VG
Voltage Higher than Three Times AVDD
ON
In exceptional cases, it may be necessary to produce a VG
voltage greater than three times AVDD. In such cases,
ON
an external charge-pump circuit can be used as shown in Figure 4. When using the device in this way, leave the FC1-,
FC1+ and FC2+ pins unconnected and set the cp_2stage bit to 1.
www.maximintegrated.com
Maxim Integrated | 48
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
4x Charge Pump
PGVDD
1mF
470nF
22nF
22nF
22nF
MAX25220/1
470nF
FC2-
1mF
VGON
<4xVAVDD
Figure 4. Quadrupler Charge-Pump at 2.1MHz
VCOM Block
VCB Transistor
Select an external npn transistor with a minimum current gain of 30. When designing the PCB, ensure that the parasitic
capacitance between the base and collector of the npn is minimized to avoid oscillation. Note that high continuous DC
current on VCOM causes very high power dissipation in the npn device and a device with low thermal resistance should
therefore be selected.
VCOM Temperature Compensation Example
Assume that an NTC with 10kΩ resistance at 25°C is connected from TEMP to GND and that the R
resistor is of
REF
value 2400Ω. At various temperatures, the following voltages will be observed on R
will be as follows:
and the ADC measurement result
REF
Table 6. ADC Result vs Temperature
TEMPERATURE
NTC RESISTANCE
R
VOLTAGE
ADC RESULT
0x02
DESIRED VCOM VOLTAGE
REF
-30°C
113kΩ
10kΩ
3kΩ
13mV
-1.09V
-1V
25°C
150mV
500mV
1V
0x1F
60°C
0x66
-0.98V
-0.91V
85°C
1.5kΩ
0xCD
The rightmost column of the previous table indicates the desired VCOM output voltage at each temperature, which will
be the inflection points in the temperature compensation curve. The following values are written to the relevant registers
(remembering that each LSB of the VCOM setting represents 6.83mV):
Table 7. VCOM Setting Example
REGISTER
FIELD
SETTING
0
NOTES
DELAYVCOM_LSB[7:0]
VCOM25
vcom25_0
vcom25[7:0]
vcom_l[4:0]
9-bit value is 011011010 or 0xDA which corresponds to -1V
Represents shift of -89mV from VCOM25
0x6D
0x0D
VCOM_L
www.maximintegrated.com
Maxim Integrated | 49
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
Table 7. VCOM Setting Example (continued)
VCOM_H1
VCOM_H2
VTEMP25
VTEMP_L
VTEMP_H1
VTEMP_H2
vcom_h1[4:0]
vcom_h2[4:0]
vtemp25[7:0]
vtemp_l[7:0]
vtemp_h1[7:0]
vtemp_h2[7:0]
0x03
0x0A
0x1F
0x02
0x66
0xCD
Represents shift of +20mV from VCOM25
Represents shift of +68mV from VCOM_H1
ADC result at 25°C
ADC result at -30°C
ADC result at 60°C
ADC result at 85°C
With these settings, the VCOM output voltage at 25°C is -1V, while at the temperature represented by 13mV at the R
REF
pin the VCOM voltage decreases to -1.09V as set by the VCOM_L register. Similarly, the VCOM_H1 and VCOM_H2
values are output on VCOM when the TEMP voltage is 500mV and 1V, respectively. In between these values the device
interpolates the correct VCOM voltage value with a resolution of 6.83mV. The complete curve is shown in Figure 5.
When setting the values VTEMP_xx and VCOM_xx, it is important to avoid values which can cause wraparound in the
temperature compensation algorithm thus possibly leading to sudden changes in the value of VCOM.
Sample VCOM Temperature Compensation Curve
1V
VCOM (V)
1V
0xCD
13mV
0x02
150mV
0x1F
499mV
0x66
ADC READING
-0.91V
VCOM_H2
-0.98V
VCOM_H1
VCOM_L
-1.09V
-1V
VCOM25
-2V
-2.49V
Figure 5. Sample VCOM Temperature Compensation Curve
Using the NV Memory
Follow the sequence below to perform non-volatile programming of the device when the auto-refresh function is not used:
2
1. Apply a voltage between 3.3V and 5V to the IN and INN pins with the device in I C mode
2. Write the desired values to be stored in OTP to the registers from 0x07 to 0x15
3. Apply 8.5V to V
PROG
4. Optionally wait to ensure the 8.5V at V
is stable
PROG
5. Send burn_otp_reg (write any value to 0x78) command. If parity is enabled ensure the overall parity is even by
altering the final byte if necessary.
6. Wait 20ms
7. If the nv_flt bit is 0, the write was successful, go to next step. If nv_flt = 1, perform re-try (steps 5,6).
www.maximintegrated.com
Maxim Integrated | 50
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
8. Send reboot_otp (write any value to 0x79) command.
Special care is required when performing non-volatile programming with the auto-refresh feature enabled. In such cases
follow the sequence below when at least one calibration has already been performed:
1. Apply a voltage between 3.3V and 5V to the IN and INN pins
2. Write the desired values to be stored in NV memory to the registers from 0x07 to 0x15 (keep auto-refresh bit
disabled until here)
3. Enable the auto-refresh feature
4. Start polling one of the registers from 0x07 to 0x15 which has changed its value until that value gets refreshed to
the older one (auto-refresh is active)
5. The following steps from #6 to #10 must be completed within 1s
6. Write the desired values to be stored in OTP to the registers from 0x07 to 0x15 (including auto-refresh bit).
7. Apply 8.5V to V
PROG
8. Optionally wait to ensure the 8.5V at V
is stable
PROG
9. Send burn_otp_reg (write any value to 0x78) command. If parity is enabled ensure the overall parity is even by
altering the final byte if necessary
10. Wait 20ms
11. If the nv_flt bit is 0, the write was successful, go to next step. If nv_flt = 1, perform retry from step 2.
12. Send reboot_otp (write any value to 0x79) command
The non-volatile memory can be written to a total of 5 times.
Layout Considerations
The MAX25220/MAX25221/MAX25221B include high-frequency switching converters to generate the voltages for TFT-
LCDs. Take proper care while laying out the circuit board to ensure correct operation. The switching-converter portions
of the circuit have nodes with very fast voltage changes that could lead to undesirable effects on the sensitive parts of the
circuit as well as electromagnetic interference (EMI). Follow the guidelines below to reduce noise as much as possible:
● Connect the bypass capacitors on IN and INN as close as possible to the device and connect the capacitor ground to
the analog ground plane using vias close to the capacitor terminal. Ensure that the power connection to IN and INN
uses a very wide trace or complete board layer to avoid input undervoltage problems.
● Connect the GND pin of the device to the analog ground plane using a via close to GND. Lay the analog ground plane
on the inner layer, preferably next to the top layer. Use the analog ground plane to cover the entire area under critical
signal components for the power converter.
● Have a power-ground plane for the switching-converter power circuit under the power components (i.e., input filter
capacitor, output filter capacitor, inductor, MOSFET, rectifier diode, and current-sense resistor). Connect PGND to the
power-ground plane closest to PGND. Connect all other ground connections to the power ground plane using vias
close to the terminals.
● Minimize the copper area of all switching nodes to avoid EMI. Minimize the loop areas for the AVDD and NAVDD
converters by placing all components close to the LXP and LXN pins. Place the input and output capacitor grounds
close to each other. In the case of AVDD the input/output capacitor grounds should also connect directly to the PGND
pin.
● Connect GND, CPGND and PGND at the exposed pad of the device.
● Refer to the MAX25220/MAX25221/MAX25221B evaluation kit (EV kit) data sheet for a sample layout.
In addition, when using an external NTC temperature sensor for temperature compensation connect the grounded end
directly to the grounded end of the RREF resistor. This avoids possible differences in ground potential between different
points on the circuit board.
www.maximintegrated.com
Maxim Integrated | 51
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
Typical Application Circuits
MAX25220 Applications Diagram
TFT POWER INPUT
10mF
IN
V18
FC2+
1mF
FC2-
FC1+
FC1-
PGVDD
VGON
1mF
TFT POWER INPUT
BST
VGOFF
DN
L3
LX
MAX25220
HVINP
10mF
PGND
AVDD
2.2mF
GND
EN
TFT POWER INPUT
INN
NAVDD
LXN
SDA
SCL
FLT
I2C BUS
FAULT OUTPUT
VPROG
EP
CPGND
DGND
ADD
10mF
www.maximintegrated.com
Maxim Integrated | 52
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
Typical Application Circuits (continued)
MAX25221 Applications Diagram
TFT POWER INPUT
10mF
IN
PGVDD
V18
1mF
1mF
VCOM
FC2+
FC2-
0.1mF
VCOMN
VCB
FC1+
1mF
1kW
FC1-
VGON
NAVDD
TEMP
T
TFT POWER INPUT
BST
VGOFF
0.1mF
MAX25221/B
LX
DN
1mF
HVINP
10mF
RREF
PGND
AVDD
2.2mF
GND
EN
TFT POWER INPUT
INN
NAVDD
SDA
I2C BUS
SCL
FLT
LXN
FAULT OUTPUT
VPROG
EP
CPGND
DGND
ADD
10mF
www.maximintegrated.com
Maxim Integrated | 53
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
Ordering Information
PART NUMBER
MAX25220ATJ/V+
MAX25221ATJ/V+
MAX25220ATJ/VY+
MAX25221ATJ/VY+*
MAX25221BATJ/V+
TEMPERATURE RANGE
PIN-PACKAGE
32 TQFN-EP
FEATURES
Without VCOM buffer
-40 to +125°C
-40 to +125°C
-40 to +125°C
-40 to +125°C
-40 to +125°C
32 TQFN-EP
With VCOM buffer
32 SWTQFN-EP
32 SWTQFN-EP
32 TQFN-EP
Without VCOM buffer
With VCOM buffer
EN pin turn-on, VCOM buffer
+ Denotes a lead(Pb)-free/RoHS-compliant package.
/V denotes an automotive qualified part.
Y = Side-wettable package.
T Denotes tape-and-reel.
*Future product - contact factory for availability.
www.maximintegrated.com
Maxim Integrated | 54
MAX25220/MAX25221/
MAX25221B
Automotive 4-Channel TFT-LCD Power Supply
with VCOM Buffer
Revision History
REVISION REVISION
PAGES
DESCRIPTION
CHANGED
NUMBER
DATE
5/20
6/20
6/20
0
1
2
Initial release
—
Removed future product notation from MAX25221ATJ/V+ in Ordering Information
Added Typical Operating Characteristics
54
14, 15
Updated Package Information and Electrical Characteristics; removed future product
notation for MAX25220ATJ/VY+ in Ordering Information
3
4
10/20
11/20
7, 11, 54
19, 54
Updated Pin Descriptions and Ordering Information.
For pricing, delivery, and ordering information, please visit Maxim Integrated’s online storefront at https://www.maximintegrated.com/en/storefront/storefront.html.
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent
licenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max
limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
© 2020 Maxim Integrated Products, Inc.
相关型号:
©2020 ICPDF网 联系我们和版权申明