MAX20812TAFH [MAXIM]
Dual-Output, 6A, 3MHz, 2.7V to 16V, Step-Down Switching Regulator;
| 型号： | MAX20812TAFH |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Dual-Output, 6A, 3MHz, 2.7V to 16V, Step-Down Switching Regulator |
| 文件： | 总26页 (文件大小：876K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Click here for production status of specific part numbers.
MAX20812
Dual-Output, 6A, 3MHz, 2.7V to 16V, Step-Down
Switching Regulator
General Description
Benefits and Features
The MAX20812 is a dual-output, fully integrated, highly
efficient, step-down DC-DC switching regulator. This
device operates from 2.7V to 16V input supplies, and
each output can be regulated from 0.5V to 5.8V. The IC
delivers up to 6A of load current per output. The two
outputs can be connected in parallel as a single-output,
dual-phase regulator that supports up to 12A load
current.
•
High Power Density with Low Component Count
• Dual-Output or Dual-Phase Operation
• Single-Supply Operation with Integrated LDO for
Bias Generation
• Optional 2.5V to 5.5V External Bias for Higher
Efficiency
• Compact 3.5mm x 4.6mm, 21-Pin, FC2QFN
Package
• Internal Compensation
Wide Operating Range
The switching frequency of this device can be configured
from 500kHz to 3.0MHz and provides the capability of
optimizing the design in terms of solution size and
performance.
•
• 2.7V to 16V Input Voltage Range
• 0.5V to 5.8V Output Voltage Range
• 500kHz to 3MHz Configurable Switching
Frequency
• -40°C to +125°C Junction Temperature Range
• Three Pin-Strap Programming Pins to Select
Different Configurations
• Independent Enable and Power Good for Each
Output
Optimized Performance and Efficiency
The MAX20812 utilizes fixed-frequency, current-mode
control with internal compensation. The dual-switching
regulators operate 180° out-of-phase. The MAX20812
features a selectable advanced modulation scheme
(AMS) to provide improved dynamic load transient
performance. The device also features selectable
discontinuous current mode (DCM) operation to improve
light load efficiency. Operation settings and configurable
features can be selected by connecting pin-strap
resistors from the PGM_ pins to ground.
•
• 92.5% Peak Efficiency with V
= 12V,
DDH
= 1MHz
V
OUT
= 1.8V, and f
SW
• Interleaved 180° Out-of-Phase Operation
• Selectable AMS to Improve Load Transient
• Selectable DCM to Improve Light Load Efficiency
• Active Current Balancing for Dual-Phase
Operation
The MAX20812 has an internal 1.8V LDO output to
power the gate drives (V ) and internal circuitry
CC
(AVDD). The device also has an optional LDO input pin
(LDOIN), allowing connection from a 2.5V to 5.5V bias
input supply for optimized efficiency.
Electrical and Thermal Ratings
The MAX20812 integrates multiple protections including
positive and negative overcurrent protection, output
overvoltage protection, and overtemperature protection
to ensure a robust design.
CURRENT
RATING*
(DUAL-
PHASE)
(A)
INPUT
VOLTAGE VOLTAGE
OUTPUT
DESCRIPTION
(V)
2.7 to 16
12
(V)
0.5 to 5.8
1.8
The MAX20812 is available in a compact 3.5mm x
4.6mm FC2QFN package that supports -40°C to +125°C
junction temperature operation.
Electrical Rating
Thermal Rating
12
T
= +85°C,
12
12
A
Applications
No Air Flow
Thermal Rating
•
•
•
•
•
•
Communications Equipment
Networking Equipment
Servers and Storage Equipment
Point-of-Load Voltage Regulators
μP Chipsets
Memory V
DDQ
I/O Pins of an FPGA/DSP/MCU
T
= +55°C,
12
5.0
A
200LFM Air Flow
*Maximum T = +125°C. For specific operating conditions, see
J
the Safe Operating Area (SOA) curves in the Typical Operating
Characteristics.
•
Ordering Information appears at end of data sheet.
19-100887; Rev 1; 3/21
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Click here for production status of specific part numbers.
MAX20812
Dual-Output, 6A, 3MHz, 2.7V to 16V, Step-Down
Switching Regulator
Simplified Application Circuits
DUAL-OUTPUT APPLICATION CIRCUIT
2.7V TO 16V INPUT
MAX20812
BST2
V
DDH1
V
DDH2
LX2
OUTPUT2: 0.5V TO 5.8V, 6A
OPTIONAL 2.5V TO 5.5V
LDOIN
SNSP2
V
CC
AVDD
BST1
PGOOD1
PGOOD2
EN1
LX1
OUTPUT1: 0.5V TO 5.8V, 6A
SNSP1
EN2
PGM0
PGM1
PGM2
PGND1
PGND2
AGND
SINGLE-OUTPUT DUAL-PHASE APPLICATION CIRCUIT
2.7V TO 16V INPUT
MAX20812
BST2
LX2
V
DDH1
V
DDH2
OUTPUT: 0.5V TO 5.8V, 12A
LDOIN
OPTIONAL 2.5V TO 5.5V
AVDD
COUPLED
INDUCTOR
OR
DISCRETE
INDUCTORS
SNSP2
BST1
V
CC
AVDD
PGOOD1
PGOOD2
EN1
LX1
SNSP1
EN2
PGM0
PGM1
PGM2
PGND1
PGND2
AGND
19-100887; Rev 1; 3/21
MAX20812
Dual-Output, 6A, 3MHz, 2.7V to 16V, Step-Down
Switching Regulator
Absolute Maximum Ratings
PGND to AGND..................................................-0.3V to +0.3V
VDDH1, VDDH2 to PGND (Note 1)......................... -0.3V to +19V
LX1, LX2 to PGND (DC) ..................................... -0.3V to +19V
LX1, LX2 to PGND (AC) (Note 2) ........................ -10V to +23V
VCC to PGND......................................................-0.3V to +2.5V
AVDD to AGND ..................................................-0.3V to +2.5V
EN1, EN2 to AGND ...............................................-0.3V to +4V
PGOOD1, PGOOD2 to AGND ..............................-0.3V to +4V
SNSP1, SNSP2 to AGND.........................-0.3V to AVDD+0.3V
LDOIN to AGND ....................................................-0.3V to +6V
PGM0, PGM1, PGM2 to AGND................-0.3V to AVDD+0.3V
Peak LX_ Current .................................................-12A to +19A
Junction Temperature (TJ).............................................+150°C
Storage Temperature Range.......................... -65°C to +150°C
Peak Reflow Temperature Lead-Free...........................+260°C
VDDH1 to LX1 (DC) (Note 1) ................................ -0.3V to +19V
VDDH1 to LX1 (AC) (Note 2) ................................. -10V to +19V
VDDH2 to LX2 (DC) (Note 1) ................................ -0.3V to +19V
VDDH2 to LX2 (AC) (Note 2) ................................. -10V to +19V
BST1, BST2 to PGND (DC)............................. -0.3V to +21.5V
BST1, BST2 to PGND (AC) (Note 2) .................. -7V to +25.5V
BST1 to LX1....................................................... -0.3V to +2.5V
BST2 to LX2....................................................... -0.3V to +2.5V
Note 1:
Note 2:
Input HF capacitors placed not more than 40 mils away from the VDDH_ pins are required to keep inductive voltage spikes
within Absolute Maximum limits.
AC is limited to 25ns.
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
21 FC2QFN
Ordering Part Number
MAX20812AFH+ (exposed top)
F213A4F+1
MAX20812TAFH+ (closed top)
F213A4F+2
Package Code
Outline Number
21-100394
21-100513
Land Pattern Number
90-100134
90-100184
Thermal Resistance, Four-Layer Board
Junction to Ambient (θJA) JEDEC
Junction to Ambient (θJA) on MAX20812EVKIT#
Junction to Case (θJC)
44.96°C/W
20°C/W
43.9°C/W
20°C/W
0.51°C/W
10.1°C/W
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 | 3
MAX20812
Dual-Output, 6A, 3MHz, 2.7V to 16V, Step-Down
Switching Regulator
Electrical Characteristics
(See the Typical Application Circuits. V
= V
= 12V, V
= 3.3V, T = T = -40°C to +125°C, unless otherwise noted.
LDOIN A J
DDH1
DDH2
Specifications are production tested at T = +32°C; limits within the operating temperature range are guaranteed by design and
A
characterization.)
PARAMETER
INPUT SUPPLY
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Input Voltage Range
V
2.7
16
V
DDH
V
V
= 3.3V, EN_ = AGND
= AVDD, EN_ = AGND
0.1
2.2
LDOIN
LDOIN
Input Supply Current
I
mA
VDDH
Linear Regulator Input
Voltage
V
2.5
5.5
V
mA
V
LDOIN
LDOIN
V
V
= 3.3V, EN_ = AGND
2.6
Linear Regulator Input
Current
LDOIN
LDOIN
I
= 3.3V, EN_ = 1.8V, f
= 1MHz
22.1
SW
Internal LDO Regulated
Output
V
1.71
1.95
CC
V
V
V
= AVDD
= 3.3V
80
LDOIN
LDOIN
Linear Regulator
Current Limit
100
mA
< 1.6V
20
CC
AVDD Undervoltage
Lockout
AVDD Undervoltage
Lockout Hysteresis
AVDD
Rising
1.65
2.4
1.67
1.70
2.6
V
mV
V
UVLO
55
2.5
100
2.3
100
V
Undervoltage
DDH_
V
Rising
DDH_UVLO
Lockout
V
Undervoltage
DDH_
mV
V
Lockout Hysteresis
LDOIN Undervoltage
Lockout
LDOIN Undervoltage
Lockout Hysteresis
VLDOIN_UVLO
2.2
2.4
V
mV
LDOIN_UVLO
OUTPUT VOLTAGE RANGE AND ACCURACY
0.4945
0.497
0.500
0.500
0.5055
0.503
Internal Reference
Voltage
V
T
T
= T = 0°C to +85°C
J
A
A
Voltage Sense Leakage
Current
I
= T = +25°C
1
µA
SNSP_
J
SWITCHING FREQUENCY
500
750
1000
1500
2000
3000
Switching Frequency
f
kHz
SW_
Switching Frequency
Accuracy
Phase Shift Between
Two Outputs/Phases
-10
+10
%
°
f
= f
SW2
180
SW1
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Maxim Integrated | 4
MAX20812
Dual-Output, 6A, 3MHz, 2.7V to 16V, Step-Down
Switching Regulator
(See the Typical Application Circuits. V
= V
= 12V, V
= 3.3V, T = T = -40°C to +125°C, unless otherwise noted.
LDOIN A J
DDH1
DDH2
Specifications are production tested at T = +32°C; limits within the operating temperature range are guaranteed by design and
A
characterization.)
PARAMETER
SYMBOL
CONDITIONS
(Note 3)
(Note 3)
MIN
TYP
MAX
UNITS
Minimum Controllable
On-Time
Minimum Controllable
Off-Time
I
I
= 0A
= 0A
40
47
ns
OUT
100
800
110
ns
OUT
ENABLE AND STARTUP
Initialization Time
t
µs
V
INIT
Rising
Falling
0.9
EN_ Threshold
0.6
t
EN_RISING_DE
Rising
Falling
200
LAY
EN_ Filtering Delay
Soft-Start Time
µs
t
EN_FALLING_D
2
3
ELAY
t
ms
SS
POWER GOOD AND FAULT PROTECTIONS
PGOOD_ Output Low
I
= 4mA
0.4
-10
V
PGOOD
Output Undervoltage
(UV) Threshold
Output UV Deglitch
Delay
Output Overvoltage
Protection (OVP)
Threshold
-16
10
-13
4
%
μs
%
13
16
Output OVP Threshold
Deglitch Delay
2
μs
Positive Overcurrent
Protection (POCP)
Threshold
Inductor peak current, POCP = 9A
Inductor peak current, POCP = 6A
7.65
5.1
9.00
6.0
36
10.35
6.9
POCP
A
ns
A
POCP Deglitch Delay
Fast Positive
Overcurrent Protection
(FPOCP) Threshold
Negative Overcurrent
Protection (NOCP)
Threshold to POCP
Threshold Ratio
FPOCP
NOCP
12.5
14.5
-83
16.5
With respect to POCP threshold (typ)
%
NOCP Accuracy
-20
1.47
1.41
+20
1.62
1.56
%
V
V
Rising
Falling
1.57
1.51
BST
BST UVLO Threshold
Overtemperature
Protection (OTP) Rising
Threshold
OTP
155
°C
OTP Accuracy
6
%
°C
ms
OTP Hysteresis
20
20
Hiccup Protection Time
t
HICCUP
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Maxim Integrated | 5
MAX20812
Dual-Output, 6A, 3MHz, 2.7V to 16V, Step-Down
Switching Regulator
(See the Typical Application Circuits. V
= V
= 12V, V
= 3.3V, T = T = -40°C to +125°C, unless otherwise noted.
LDOIN A J
DDH1
DDH2
Specifications are production tested at T = +32°C; limits within the operating temperature range are guaranteed by design and
A
characterization.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
DCM OPERATION MODE
Inductor valley
current
Inductor valley
current
POCP = 9A
-440
-310
100
DCM Comparator
Threshold to Enter DCM
mA
mA
POCP = 6A
DCM Comparator
Threshold to Exit DCM
Inductor valley current
PROGRAMMING PINS
PGM_ Pin Resistor
Range
PGM_ Resistor
Accuracy
R
0.095
-1
115
+1
kΩ
PGM_
%
Guaranteed by design.
Note 3:
Typical Operating Characteristics
(Typical Application Circuits, V
= 12V, tested on MAX20812EVKIT#, T = +25°C, unless otherwise noted.)
DDH
A
EFFICIENCY (MAX20812)
(SINGLE-PHASE, L = PA5003.XXXNLT)
EFFICIENCY (MAX20812)
(SINGLE-PHASE, L = PA5003.XXXNLT)
EFFICIENCY (MAX20812)
(SINGLE-PHASE, L = PA5003.XXXNLT)
(VDDH = 12V, fSW = 1MHz, VLDOIN = 3.3V)
(VDDH = 12V, fSW = 1MHz, VLDOIN = OPEN)
(VDDH = 5V, fSW = 1MHz, VLDOIN = OPEN)
toc01
toc02
toc03
100
95
90
85
80
75
70
65
100
95
90
85
80
75
70
65
100
95
90
85
80
75
70
65
VOUT = 0.8V
VOUT = 1.0V
VOUT = 1.2V
VOUT = 1.8V
VOUT = 3.3V
VOUT = 5.0V
VOUT = 0.8V
VOUT = 1.0V
VOUT = 1.2V
VOUT = 1.8V
VOUT = 3.3V
VOUT = 5.0V
VOUT = 0.8V
VOUT = 1.0V
VOUT = 1.2V
VOUT = 1.8V
VOUT = 3.3V
0
1
2
3
4
5
6
0
1
2
3
4
5
6
0
1
2
3
4
5
6
LOAD CURRENT (A)
LOAD CURRENT (A)
LOAD CURRENT (A)
EFFICIENCY (MAX20812)
(SINGLE-PHASE, L = PA5005.XXXNLT)
(VDDH = 12V, fSW = 500kHz, VLDOIN = 3.3V)
EFFICIENCY (MAX20812)
(SINGLE-PHASE, L = PA5005.XXXNLT)
(VDDH = 12V, fSW = 500kHz, VLDOIN = OPEN)
EFFICIENCY
(MAX20812, DCM vs CCM)
(VDDH = 12V, VOUT = 1.0V, VLDOIN = OPEN)
toc04
toc05
toc06
100
95
90
85
80
75
70
65
100
95
90
85
80
75
70
65
80
70
60
50
40
30
20
VOUT = 0.8V
VOUT = 1.0V
VOUT = 1.2V
VOUT = 1.8V
VOUT = 3.3V
VOUT = 5.0V
VOUT = 0.8V
VOUT = 1.0V
VOUT = 1.2V
VOUT = 1.8V
VOUT = 3.3V
VOUT = 5.0V
DCM ENABLED
DCM DISABLED
0
0.1
0.2
0.3
0.4
0.5
0.6
0
1
2
3
4
5
6
0
1
2
3
4
5
6
LOAD CURRENT (A)
LOAD CURRENT (A)
LOAD CURRENT (A)
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Maxim Integrated | 6
MAX20812
Dual-Output, 6A, 3MHz, 2.7V to 16V, Step-Down
Switching Regulator
LOAD AND LINE REGULATIONS
(SINGLE-PHASE OPERATION)
SAFE OPERATING AREA (MAX20812)
(VDDH = 12V, fSW = 1MHz, VLDOIN = 3.3V)
EXTERNAL BIAS SUPPLY CURRENT
(MAX20812, VLDOIN = 3.3V)
(VOUT = 1.8V)
(400LFM AIR FLOW, NO HEATSINK, 2 PHASE)
toc07
toc08
toc09
1.801
1.8008
1.8006
1.8004
1.8002
1.8
50
45
40
35
30
25
20
15
10
14
12
10
8
fSW = 3MHz
f
SW = 2MHz
fSW = 1.5MHz
6
1.7998
1.7996
1.7994
1.7992
1.799
VOUT = 0.8V
VOUT = 1.2V
VOUT = 1.8V
VOUT = 3.3V
VOUT = 5.0V
VIN = 2.7V
VIN = 5.0V
VIN = 9.0V
VIN = 12V
VIN = 16V
4
2
fSW = 1MHz
fSW = 750kHz
fSW = 500kHz
0
2
4
6
8
10
12
14
16
75
85
95
105
115
125
0
1
2
3
4
5
6
INPUT VOLTAGE (V)
AMBIENT TEMPERATURE (°C)
LOAD CURRENT (A)
SAFE OPERATING AREA (MAX20812)
(VDDH = 12V, fSW = 1MHz, VLDOIN = 3.3V)
SAFE OPERATING AREA (MAX20812)
(VDDH = 12V, fSW = 1MHz, VLDOIN = 3.3V)
(NO AIR FLOW, NO HEATSINK, 2 PHASE)
SAFE OPERATING AREA (MAX20812)
(VDDH = 12V, fSW = 1MHz, VLDOIN = OPEN)
(200LFM AIR FLOW, NO HEATSINK, 2 PHASE)
(400LFM AIR FLOW, NO HEATSINK, 2 PHASE)
toc10
toc11
toc12
14
12
10
8
14
12
10
8
14
12
10
8
6
6
6
VOUT = 0.8V
VOUT = 1.2V
VOUT = 1.8V
VOUT = 3.3V
VOUT = 5.0V
VOUT = 0.8V
VOUT = 1.2V
VOUT = 1.8V
VOUT = 3.3V
VOUT = 5.0V
VOUT = 0.8V
VOUT = 1.2V
VOUT = 1.8V
VOUT = 3.3V
VOUT = 5.0V
4
4
4
2
2
2
0
0
0
75
85
95
105
115
125
75
85
95
105
115
125
75
85
95
105
115
125
AMBIENT TEMPERATURE (°C)
AMBIENT TEMPERATURE (°C)
AMBIENT TEMPERATURE (°C)
SAFE OPERATING AREA (MAX20812)
(VDDH = 12V, fSW = 1MHz, VLDOIN = OPEN)
SAFE OPERATING AREA (MAX20812)
(VDDH = 12V, fSW = 1MHz, VLDOIN = OPEN)
SAFE OPERATING AREA (MAX20812)
(VDDH = 5V, fSW = 1MHz, VLDOIN = OPEN)
(200LFM AIR FLOW, NO HEATSINK, 2 PHASE)
(NO AIR FLOW, NO HEATSINK, 2 PHASE)
(400LFM AIR FLOW, NO HEATSINK, 2 PHASE)
toc13
toc14
toc15
14
12
10
8
14
12
10
8
14
12
10
8
6
6
6
VOUT = 0.8V
VOUT = 1.2V
VOUT = 1.8V
VOUT = 3.3V
VOUT = 5.0V
VOUT = 0.8V
VOUT = 1.2V
VOUT = 1.8V
VOUT = 3.3V
VOUT = 5.0V
4
4
4
VOUT = 0.8V
VOUT = 1.2V
VOUT = 1.8V
VOUT = 3.3V
2
2
2
0
0
0
75
85
95
105
115
125
75
85
95
105
115
125
75
85
95
105
115
125
AMBIENT TEMPERATURE (°C)
AMBIENT TEMPERATURE (°C)
AMBIENT TEMPERATURE (°C)
STARTUP
(SINGLE-PHASE OPERATION)
(IOUT1 = 6A)
SAFE OPERATING AREA (MAX20812)
(VDDH = 5V, fSW = 1MHz, VLDOIN = OPEN)
SAFE OPERATING AREA (MAX20812)
(VDDH = 5V, fSW = 1MHz, VLDOIN = OPEN)
(NO AIR FLOW, NO HEATSINK, 2 PHASE)
(200LFM AIR FLOW, NO HEATSINK, 2 PHASE)
toc18
toc17
toc16
14
12
10
8
14
12
10
8
200mV/div
2V/div
2V/div
EN1
PGOOD1
6
6
4
4
VOUT1
VOUT = 0.8V
VOUT = 1.2V
VOUT = 1.8V
VOUT = 3.3V
VOUT = 0.8V
VOUT = 1.2V
VOUT = 1.8V
VOUT = 3.3V
2
2
LX1
10V/div
0
0
75
85
95
105
115
125
75
85
95
105
115
125
500μs/div
AMBIENT TEMPERATURE (°C)
AMBIENT TEMPERATURE (°C)
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Maxim Integrated | 7
MAX20812
Dual-Output, 6A, 3MHz, 2.7V to 16V, Step-Down
Switching Regulator
PRE-BIASED STARTUP
(SINGLE-PHASE OPERATION)
SHUTDOWN
(SINGLE-PHASE OPERATION)
(IOUT1 = 3A)
OUTPUT VOLTAGE RIPPLE
(SINGLE-PHASE OPERATION)
(OUT1 = 1.0V, 1MHz; OUT2 = 1.8V, 2MHz)
(VPREBIAS = 0.5V)
toc19
toc22
toc25
toc20
toc21
200mV/div
2V/div
VOUT1
EN1
VOUT1
20mV/div
500mV/div
2V/div
EN1
2V/div
10V/div
PGOOD1
LX1
VOUT1
2V/div
PGOOD1
LX1
VOUT2
20mV/div
LX1
10V/div
LX2
10V/div
10V/div
500μs/div
2μs/div
1μs/div
OUTPUT VOLTAGE RIPPLE
(DCM OPERATION)
(VOUT = 1.8V, IOUT = 100mA)
LOAD-TRANSIENT RESPONSE
(SINGLE-PHASE OPERATION)
(VOUT1 = 1.0V, 1A TO 6A, 10A/μs)
CURRENT BALANCE
(DUAL-PHASE OPERATION)
(IOUT = 0A to 8A LOAD TRANSIENT)
toc24
toc23
VOUT
50mV/div
VOUT
100mV/div
1
VOUT1
20mV/div
5A/div
2A/div
2A/div
ILX2
ILX1
IOUT1
LX1
5V/div
5A/div
IOUT
100μs/div
20μs/div
4μs/div
POSITIVE OVERCURRENT PROTECTION
(SINGLE-PHASE OPERATION)
(VOUT1 = 1.2V, fSW1 = 1MHz, POCP = 9A)
CURRENT BALANCE
(DUAL-PHASE OPERATION)
(IOUT = 8A to 0A LOAD TRANSIENT)
BODE PLOT
(SINGLE-PHASE OPERATION)
(VOUT1 = 1.8V, IOUT1 = 6A, fSW1 = 2MHz)
toc27
toc26
100
80
200
160
120
80
VOUT1
VOUT
50mV/div
PHASE MARGIN = 59°
60
500mV/div
5A/div
40
20
40
ILX1
ILX2
0
0
ILX1
-20
-40
-60
-80
-100
-40
-80
-120
-160
-200
2A/div
2A/div
BANDWIDTH = 208kHz
PGOOD1
GAIN MARGIN = 14dB
2V/div
IOUT
LX1
10V/div
5A/div
10
100
FREQUENCY (kHz)
1000
4μs/div
200μs/div
POCP HICCUP AND AUTO-RETRY
(SINGLE-PHASE OPERATION)
(VOUT1 = 1.2V, fSW1 = 1MHz, POCP = 9A)
toc28
VOUT1
500mV/div
5A/div
ILX1
PGOOD1
2V/div
LX1
10V/div
10ms/div
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Maxim Integrated | 8
MAX20812
Dual-Output, 6A, 3MHz, 2.7V to 16V, Step-Down
Switching Regulator
Pin Configuration
21
18
20
19
1
17
V
DDH2
V
DDH1
PGND2
2
16
PGND1
EN2
PGOOD1
PGM2
3
4
5
6
15
14
13
12
V
CC
MAX20812
PGOOD2
PGM1
EN1
PGM0
7
8
9
10
11
(TOP VIEW)
Pin Descriptions
PIN
NAME
FUNCTION
and V should be connected on the PCB.
1
V
Regulator Input Supply for OUTPUT2. V
DDH1
DDH2
DDH2
2
PGND2
EN2
Power Ground. PGND1 and PGND2 should be connected on the PCB.
Output Enable for OUTPUT2.
3
4
PGOOD1 Open-Drain Power-Good Output for OUTPUT1.
5
PGM2
PGM0
Program Input. Connect this pin to ground though a programming resistor.
Program Input. Connect this pin to ground though a programming resistor.
6
OUTPUT2 Voltage Sense Feedback Pin. Connect SNSP2 to V
at the load. A resistive voltage-
OUT2
7
8
SNSP2
AVDD
divider can be inserted between the output and SNSP2 to regulate the output above the 0.5V fixed
reference voltage. Connect SNSP2 to AVDD to select dual-phase operation.
1.8V Supply for Analog Circuitry. Connect a 2.2Ω to 4.7Ω resistor from AVDD to V . Connect a 1μF or
CC
greater ceramic capacitor from AVDD to AGND.
Optional 2.5V to 5.5V LDO Input Supply. Connect this pin to AVDD or GND, or leave this pin floating if
unused.
9
LDOIN
AGND
10
Analog Ground.
OUTPUT1 Voltage Sense Feedback Pin. Connect SNSP1 to V
at the load. A resistive voltage-
OUT1
11
12
SNSP1
EN1
divider can be inserted between the output and SNSP1 to regulate the output above the 0.5V fixed
reference voltage.
Output Enable for OUTPUT1.
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Maxim Integrated | 9
MAX20812
Dual-Output, 6A, 3MHz, 2.7V to 16V, Step-Down
Switching Regulator
13
14
15
16
17
18
19
20
21
PGM1
Program Input. Connect this pin to ground though a programming resistor.
PGOOD2 Open-Drain Power-Good Output for OUTPUT2.
V
Internal 1.8V LDO Output. Connect a 2.2μF or greater ceramic capacitor from V
to PGND.
CC
CC
PGND1
Power Ground. PGND1 and PGND2 should be connected on the PCB.
V
Regulator Input Supply for OUTPUT1. V
and V
should be connected on the PCB.
DDH1
DDH1
DDH2
BST1
LX1
Bootstrap Pin for OUTPUT1. Connect a 0.22μF ceramic capacitor from BST1 to LX1.
Switching Node of OUTPUT1. Connect LX1 directly to the output inductor.
Switching Node of OUTPUT2. Connect LX2 directly to the output inductor.
Bootstrap Pin for OUTPUT2. Connect a 0.22μF ceramic capacitor from BST2 to LX2.
LX2
BST2
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Maxim Integrated | 10
MAX20812
Dual-Output, 6A, 3MHz, 2.7V to 16V, Step-Down
Switching Regulator
Block Diagram
PGOOD1
EN2
PGOOD2
AVDD
V
CC
EN1
CLOCK
DIGITAL CORE
OTP BANK
LDO
LDOIN
TO ANALOG/
PGM0
PGM1
PGM2
DIGITAL CORE
TO
GATE
DRIVE
RADC
FAULT
DETECT
BST1
BST
SNSP1
CONTROLLER
1
V
DDH1
MODULATOR
1
HS
PWM
DRIVER
LOGIC
OVP
PGOOD
LX1
IRECON
LS
DRIVER
PGND1
ZERO
CROSS
OVP
PGOOD
FAULT
DETECT
BST2
BST
SNSP2
AGND
CONTROLLER
2
V
DDH2
MODULATOR
2
HS
PWM
DRIVER
LOGIC
BANDGAP
CORE
LX2
IRECON
LS
DRIVER
BIAS
PGND2
ZERO
CROSS
MAX20812
Detailed Description
Dual-Output or Dual-Phase Operation
The MAX20812 by default is configured as a dual-output step-down regulator. This device has two independent control
loops for the two outputs, and the loop parameters can be independently selected.
This device can also each be configured as a single output, dual-phase 12A converter by connecting the SNSP2 pin to
AVDD. When configured to dual-phase operation, only the control loop for OUTPUT1 will work, and the control loop for
OUTPUT2 is bypassed. EN1 and PGOOD1 are used in dual-phase operation mode to enable the device and indicate
power-good status. EN2 and PGOOD2 can be disconnected.
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Maxim Integrated | 11
MAX20812
Dual-Output, 6A, 3MHz, 2.7V to 16V, Step-Down
Switching Regulator
Control Architecture
Fixed-Frequency, Peak Current-Mode Control Loop
The MAX20812 control loops are based on fixed-frequency, peak current-mode control architecture. A simplified control
architecture is shown in Figure 1. Each loop contains an error amplifier stage, internal voltage loop compensation network,
current sense, internal slope compensation, and a PWM modulator that generates the PWM signals to drive high-side
and low-side MOSFETs. The device has a fixed 0.5V reference voltage (V
). The difference of V
and the sensed
REF
REF
) is used as the input of the voltage loop
output voltage is amplified by the first error amplifier. Its output voltage (V
ERR_
compensation network. The output of the compensation network (V
) is fed to a PWM comparator with the current-
COMP_
). The output of the PWM comparator is the input of the PWM
sense signal (V
) and slope compensation (V
RAMP_
ISENSE_
modulator. The turning on of the high-side MOSFET is aligned with an internal clock. It can either be a fixed-frequency
clock or a phase-shifted clock if AMS is enabled.
AMS_ENABLE
CLOCK
FIXED_CLK
AMS_CLK
PWM
MODULATOR
V
REF
VOLTAGE LOOP
COMPENSATION
NETWORK
V
V
COMP_
ERR_
V
SNSP_
V
ISENSE_
V
RAMP_
Figure 1. Simplified Control Architecture
Advanced Modulation Scheme (AMS)
The MAX20812 offers a selectable AMS to provide improved dynamic load-transient response. AMS provides a significant
advantage over conventional fixed-frequency PWM schemes. Enabling the AMS feature allows for modulation at both
leading and trailing edges, which results in a fast switching response during large load transients. Figure 2 shows the
scheme to include leading-edge modulation to the traditional trailing-edge modulation when AMS is enabled in the device.
The modulation scheme allows the turn on and off with minimal delay. Since the total inductor current increases very
quickly, thus satisfying the load demand, the current drawn from the output capacitors is reduced. With AMS enabled, the
system closed-loop bandwidth can be extended without phase-margin penalty. As a result, the output capacitance can
be minimized.
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Maxim Integrated | 12
MAX20812
Dual-Output, 6A, 3MHz, 2.7V to 16V, Step-Down
Switching Regulator
FIXED_CLK
-V
ERR_
AMS_RAMP
INTERMEDIATE_AMS_CLK
AMS_CLK
Figure 2. AMS Operation
Discontinuous Current Mode (DCM) Operation
Discontinuous current mode (DCM) operation can be enabled to improve light-load efficiency. V
must be at least 2V
DDH
higher than the desired V
for the device to operate in DCM. The device has a DCM current-detection comparator to
OUT
monitor the inductor valley current while operating in CCM. At light load, if the inductor valley current is below the DCM
comparator threshold for 48 consecutive cycles, the device transitions seamlessly to DCM. Once in DCM, the switching
frequency decreases as load decreases. The MAX20812 transitions back to CCM operation as soon as the inductor valley
current is higher than 100mA.
Active Current Balancing
When configured to dual-phase operation, the MAX20812 operates with active current balancing for enhanced dynamic-
current sharing or balancing between two phase currents. This feature maintains the current balance during load
transients, even at a load-step frequency close to the switching frequency or its harmonics. The active current-balancing
circuit adjusts the individual phase-current control signal in order to minimize the phase-current imbalance.
Internal Linear Regulator
The MAX20812 contains an internal 1.8V linear regulator. The 1.8V voltage on V
is derived from the V
pin by
DDH1
CC
default. To improve efficiency, it is recommended to apply an external 2.5V to 5.5V bias input supply on the LDOIN pin
so that the 1.8V voltage on V is converted from the LDOIN pin instead. The LDOIN pin can be connected to the output
CC
voltage if the output voltage falls within the 2.5V to 5.5V range. The optional LDOIN bias input supply can be applied or
removed anytime during regulation without affecting regulation.
The 1.8V voltage on the V
pin supplies the current to the MOSFET drivers of both outputs. A decoupling capacitor of
CC
at least 2.2μF must be connected between V
and PGND. The AVDD pin of the MAX20812 also requires a 1.8V supply
CC
to power the device’s internal analog circuitry. A 2.2Ω to 4.7Ω resistor must be connected between AVDD and V . A
CC
1μF or greater decoupling capacitor must be used between AVDD and AGND.
Startup and Shutdown
The startup and shutdown timing is shown in Figure 3. When the AVDD pin voltage is above its rising UVLO threshold,
the device goes through an initialization procedure. The dual-output or dual-phase operation is detected. Configuration
resistors on the PGM_ pins are read. Once initialization is complete, the device detects the V
UVLO and EN_ status.
DDH
When both are above their rising thresholds, soft-start begins and switching is enabled. The output voltage of the enabled
output starts to ramp up. The soft-start ramp time is 3ms. If there are no faults, the open-drain PGOOD_ pin is released
from being held low after the soft-start ramp is complete. The device supports smooth startup with the output pre-biased.
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Maxim Integrated | 13
MAX20812
Dual-Output, 6A, 3MHz, 2.7V to 16V, Step-Down
Switching Regulator
During operation, if either V
UVLO or EN_ falls below its threshold, switching is stopped immediately. The PGOOD_
DDH
pin is driven low. The output voltage is discharged by the load current.
V
DDH
V
CC
AND AVDD
EN_
t
INIT
t
SS
t
EN_FALLING_DELAY
V
OUT_
(PRE-BIASED)
INTERNAL
SOFT-START RAMP
t
EN_RISING_DELAY
PGOOD_
LX_
t
t
t
t
= 800µs
INIT
= 200µs
EN_RISING_DELAY
= 3ms
SS
= 2µs
EN_FALLING_DELAY
Figure 3. Startup and Shutdown Timing
Fault Handling
Input Undervoltage Lockout (V
UVLO)
DDH
The MAX20812 internally monitors V
with a UVLO circuit. When the input supply voltage is below the UVLO threshold,
DDH
the device stops switching and drives the PGOOD_ pin low. The device restarts after 20ms hiccup protection time if the
UVLO status is cleared. See the Startup and Shutdown section for the startup sequence.
V
DDH
Output Overvoltage Protection (OVP)
The feedback voltage on SNSP_ is monitored for overvoltage once the soft-start ramp is complete. If the feedback voltage
is above the OVP threshold beyond the OVP deglitch filtering delay, the device stops switching and drives the PGOOD_
pin low. The device restarts after 20ms hiccup protection time if the OVP status is cleared. When configured to dual-
output operation, the OVP of one output does not affect the operation of the other output.
Positive Overcurrent Protection (POCP)
The device’s peak current mode control architecture provides inherent current limiting and short-circuit protection. The
inductor current is continuously monitored while switching. The inductor peak current is limited on a cycle-by-cycle basis.
In each switching cycle, once the sensed inductor current exceeds the POCP threshold, the device turns off the high-side
MOSFET and turns on the low-side MOSFET to allow the inductor current to be discharged by output voltage. An up-
down counter is used to accumulate the number of consecutive POCP events each switching cycle. If the counter exceeds
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Maxim Integrated | 14
MAX20812
Dual-Output, 6A, 3MHz, 2.7V to 16V, Step-Down
Switching Regulator
1024, the device stops switching and drives the PGOOD_ pin low. The device restarts after 20ms hiccup protection time.
When configured to dual-output operation, the POCP of one output does not affect the operation of the other output.
The MAX20812 offers two POCP thresholds (9A and 6A) for each output, which can be selected by the PGM1 and PGM2
pins (see Pin-Strap Programmability). Due to POCP deglitch delay, for a specific application use case, the actual POCP
threshold should be higher (see Output Inductor Selection).
Negative Overcurrent Protection (NOCP)
The device also has negative overcurrent protection against inductor valley current. The NOCP threshold is -83% of the
POCP threshold. In each switching cycle, once the sensed inductor current exceeds the NOCP threshold, the device
turns off the low-side MOSFET and turns on the high-side MOSFET for a fixed 180ns time to allow the inductor current
to be charged by input voltage. Same as the POCP, an up-down counter is used to accumulate the number of consecutive
NOCP events. If the counter exceeds 1024, the device stops switching and drives the PGOOD_ pin low. The device
restarts after 20ms hiccup protection time. When configured to dual-output operation, the NOCP of one output does not
affect the operation of the other output.
Overtemperature Protection (OTP)
The overtemperature protection threshold is +155°C with 20°C hysteresis. If the junction temperature reaches the OTP
threshold during operation, the device stops switching and drives the PGOOD_ pin low. The device restarts if the OTP
status is cleared.
Pin-Strap Programmability
The MAX20812 has three program pins (PGM0, PGM1, and PGM2) to set some of the key configurations of the device.
A pin-strap resistor is connected from the PGM_ pin to AGND, and its value is read during startup initialization. PGM0
selects the common settings that apply to both outputs (AMS and switching frequencies). When the device is configured
to dual-output operation, PGM1 selects the POCP and internal compensation parameters of OUTPUT1; PGM2 selects
the POCP and internal compensation parameters of OUTPUT2. When the device is configured to dual-phase operation,
the POCP and internal compensation parameters are selected only by PGM1. See the Internal Compensation Selection
section for information about how to select the compensation parameters for optimized control loop performance.
Table 1. PGM0 Switching Frequency, AMS, and DCM Selections
PGM0
CODES
R
(Ω)
95.3
200
309
f
f
SW1
SW2
AMS
DCM
(kHz)
500
500
(kHz)
500
1000
750
0
1
2
750
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
422
536
649
768
750
1500
500
1000
2000
750
1500
1000
2000
3000
500
1000
750
1500
500
1000
2000
750
1000
1000
1000
1500
1500
2000
2000
3000
500
500
750
750
1000
1000
1000
1500
Disable
909
1050
1210
1400
1620
1870
2150
2490
2870
3740
8060
12400
16900
Disable
Enable
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Maxim Integrated | 15
MAX20812
Dual-Output, 6A, 3MHz, 2.7V to 16V, Step-Down
Switching Regulator
20
21
22
23
24
25
26
27
28
29
30
31
21500
26100
30900
36500
42200
48700
56200
64900
75000
86600
100000
115000
1500
2000
2000
3000
500
1500
1000
2000
3000
500
1000
750
500
1000
1500
2000
3000
500
750
1000
1000
1500
2000
3000
Enable
Table 2. PGM1 Configurations for OUTPUT1 or Dual-Phase Operation
VOLTAGE
LOOP GAIN
MULTIPLIER 1
PGM1
CODES
R
(Ω)
POCP1
(A)
SLOPE1
(μA)
0
1
2
3
4
5
6
7
95.3
200
309
422
536
649
768
909
1.5
2.6
3.7
6.0
7.0
8.0
1.5
2.6
3.7
6.0
7.0
8.0
1.5
2.6
3.7
6.0
7.0
8.0
1.5
2.6
3.7
6.0
7.0
1.5
2.6
7.0
1.5
2.6
7.0
1.5
2.6
7.0
0.4
0.7
8
9
1050
1210
1400
1620
1870
2150
2490
2870
3740
8060
12400
16900
21500
26100
30900
36500
42200
48700
56200
64900
75000
86600
100000
115000
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
9
1
1.5
0.4
0.7
1
6
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Maxim Integrated | 16
MAX20812
Dual-Output, 6A, 3MHz, 2.7V to 16V, Step-Down
Switching Regulator
Table 3. PGM2 Configurations for OUTPUT2
PGM2
CODES
0
R
POCP2
(A)
VOLTAGE LOOP GAIN
MULTIPLIER 2
SLOPE2
(μA)
1.5
2.6
3.7
6.0
7.0
8.0
1.5
2.6
3.7
6.0
7.0
8.0
1.5
2.6
3.7
6.0
7.0
8.0
1.5
2.6
3.7
6.0
7.0
1.5
2.6
7.0
1.5
2.6
7.0
1.5
2.6
7.0
(Ω)
95.3
1
200
2
3
4
5
6
7
8
9
309
422
536
649
768
909
0.4
0.7
1050
1210
1400
1620
1870
2150
2490
2870
3740
8060
12400
16900
21500
26100
30900
36500
42200
48700
56200
64900
75000
86600
100000
115000
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
9
1
1.5
0.4
0.7
1
6
Reference Design Procedure
Output Voltage Sensing
The MAX20812 has an internal 0.5V reference voltage. When the desired output voltage is higher than 0.5V, it is required
to use resistor-dividers R and R to sense the output voltage (see the Typical Application Circuits). It is
FB1
recommended that the value R
FB2
does not exceed 5kΩ. The resistor-divider ratio is given by the following equation:
FB2
R
R
FB1
V
= V
1+
OUT
REF
FB2
where:
V
V
= Output voltage
OUT
REF
= 0.5V fixed reference voltage
= Top resistor-divider
R
FB1
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Maxim Integrated | 17
MAX20812
Dual-Output, 6A, 3MHz, 2.7V to 16V, Step-Down
Switching Regulator
R
FB2
= Bottom resistor-divider
Switching Frequency Selection
The MAX20812 offers a wide range of selectable switching frequencies from 500kHz to 3MHz. Switching frequency
selection can be optimized for different applications. Higher switching frequencies are recommended for applications
prioritizing solution size so that the value and size of output LC filter can be reduced. Lower switching frequencies are
recommended for applications prioritizing efficiency and thermal dissipation due to reduced switching losses. The
frequency must be selected so that the minimum controllable on-time and minimum controllable off-time are not violated.
The maximum recommended switching frequency is calculated by the following equation:
V
V
− V
OUT
DDHMIN OUT
f
= MIN
,
SWMAX
t
V
t
V
ONMIN
DDHMAX OFFMIN
DDHMIN
where:
f
= Maximum selectable switching frequency
SWMAX
V
V
= Maximum input voltage
= Minimum input voltage
DDHMAX
DDHMIN
t
t
= Minimum controllable on-time
= Minimum controllable off-time
ONMIN
OFFMIN
Due to system noise injection, even at steady-state operation, typically the LX rising and falling edges would have some
random jittering noise. The selection of the switching frequency (f ) should take into consideration the jittering and be
SW
. To improve the LX jittering, it is recommended to use smaller inductor values and lower voltage loop
lower than f
SWMAX
gain to minimize the noise sensitivity.
Output Inductor Selection
The output inductor has an important influence on the overall size, cost, and efficiency of the voltage regulator. Since the
inductor is typically one of the larger components in the system, a minimum inductor value is particularly important in
space-constrained applications. Smaller inductor values also permit faster transient response, reducing the amount of
output capacitance needed to maintain transient tolerance.
To improve current loop noise immunity, typically the output inductor is selected so that the inductor current ripple is at
least 1A. The inductor value is calculated by the following equation:
V
(V
− V
)
OUT DDH
OUT
L =
V
I
f
DDH RIPPLE SW
where:
V
DDH
= Input voltage
I
= Inductor current ripple peak-to-peak value
RIPPLE
The inductor should also be selected so that maximum load current delivery can be guaranteed by the selected POCP
threshold. The MAX20812 offers two POCP thresholds (9A and 6A) for each output, which can be selected by the PGM1
and PGM2 pins (see Pin-Strap Programmability). Due to deglitch delay from the POCP comparator tripping to the high-
side MOSFET turning off for a specific application use case, the adjusted POCP threshold should take into consideration
the inductor value, input voltage, and output voltage, which can be calculated by the following equation:
(V
− V
) t
DDH
OUT POCP
POCP
= POCP +
ADJUST
L
where:
POCP
= Adjusted POCP threshold
ADJUST
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Maxim Integrated | 18
MAX20812
Dual-Output, 6A, 3MHz, 2.7V to 16V, Step-Down
Switching Regulator
POCP = POCP level specified in the Electrical Characteristics table
= POCP deglitch delay (36ns, typ)
t
POCP
It needs to be verified that the peak inductor current in normal operation does not exceed the minimum adjusted POCP
threshold:
I
I
RIPPLE
OUTMAX
+
POCP
ADJUST(MIN)
N
2
where:
N = Number of phases
I
= Maximum load current
OUTMAX
POCP
= Minimum adjusted POCP threshold, calculated with the minimum value of the POCP threshold
ADJUST(MIN)
Table 4 shows some suitable inductor part numbers which are verified on the MAX20812 evaluation (EV) kit to offer
optimal performance.
Table 4. Recommended Inductors
VALUE
(μH)
0.22
0.33
0.47
0.56
1.0
I
R
(mΩ)
8
FOOTPRINT
(mm)
HEIGHT
(mm)
1.2
SAT
(A)
9
8.4
26
22.2
16.5
10
DC
COMPANY
PART NUMBER
TDK
TDK
Pulse
Pulse
Pulse
Pulse
2.5 × 2.0
3.2 × 2.5
5.5 × 5.3
5.5 × 5.3
5.5 × 5.3
5.5 × 5.3
TFM252012ALMAR22MTAA
TFM322512ALMAR33MTAA
PA5003.471NLT
PA5003.561NLT
PA5003.102NLT
10
1.2
2.9
2.9
2.9
3.75
4.05
6.9
2.2
13.2
2.9
PA5003.222NLT
Output Capacitor Selection
One major factor in determining the total required output capacitance is the output-voltage ripple. To meet the output-
voltage ripple requirement, the minimum output capacitance should satisfy the following equation:
I
RIPPLE
C
OUT
8N f
(V
−ESRI
)
RIPPLE
SW
OUTRIPPLE
where:
V
= Maximum allowed output-voltage ripple
OUTRIPPLE
ESR = ESR of output capacitors
The other important factors in determining the total required output capacitance are the maximum allowable output voltage
overshoot and undershoot during load transients. For a given loading or unloading current step, the minimum required
output capacitance can be estimated by the following equation:
2
2
I
I
RIPPLE
I
N
I
N
RIPPLE
2
+
L N
− V
+
LN
2
C
MAX
,
OUT
2 V
V
(
2 V
V
)
OUT
DDH
OUT
OUT OUT
where:
= Output capacitance
C
OUT
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Maxim Integrated | 19
MAX20812
Dual-Output, 6A, 3MHz, 2.7V to 16V, Step-Down
Switching Regulator
△I = Loading or unloading current step
△V
OUT
= Maximum allowed output voltage undershoot or overshoot
Input Capacitor Selection
The input capacitance selection is determined by the input voltage ripple requirement. The V
and V pins of the
DDH2
DDH1
MAX20812 should be connected on the PCB. When configured to dual-output operation, the input capacitance is shared
between the two outputs. The minimum required input capacitance is estimated by the following equation:
I
V
I
V
OUT2(MAX) OUT2
OUT1(MAX)
OUT1
C
MAX
,
IN
f
V
V
f
V
V
SW1
DDH
INPP SW2
DDH INPP
where:
C
IN
= Input capacitance
I
= Maximum output current of OUTPUT_
= Output voltage of OUTPUT_
OUT_(MAX)
V
OUT_
f
= Switching frequency of OUTPUT_
SW_
V
INPP
= Peak-to-peak input voltage ripple
When configured to dual-phase operation, the minimum required input capacitance is estimated by the following equation:
I
V
OUT
OUT(MAX)
C
IN
2 f
V
V
INPP
SW
Besides the minimum required input capacitance, it is also required to place 0.1μF and 1μF high-frequency decoupling
capacitors next to each V pin to suppress the high-frequency switching noises.
DDH
DDH_
Internal Compensation Selection
Voltage Loop Gain
For stability purposes, it is recommended that the voltage loop bandwidth (BW) be lower than 1/5 of the switching
frequency. Consider the case of using MLCC output capacitors that have nearly ideal impedance characteristics in the
frequency range of interest with negligible ESR and ESL. The voltage loop BW can be estimated using the following
equation:
R
R
VGA
10kΩ
FB2
+ R
N
R
FB2
FB1
BW =
2π 20mΩ C
OUT
where:
= The voltage loop gain resistance, which is set by the switching frequency and voltage loop gain multiplier selected
R
VGA
by PGM_ pin resistors (Table 5)
Table 5. Voltage Loop Gain Resistance
SWITCHING
FREQUENCY
(kHz)
VOLTAGE
LOOP GAIN
MULTIPLIER
R
(kΩ)
VGA
0.4
0.7
1
15.6
27
37
500
www.maximintegrated.com
Maxim Integrated | 20
MAX20812
Dual-Output, 6A, 3MHz, 2.7V to 16V, Step-Down
Switching Regulator
1.5
0.4
0.7
1
1.5
0.4
0.7
1
1.5
0.4
0.7
1
1.5
0.4
0.7
1
52.2
22
31
44.5
62.3
22
750
1000
37
52.2
74.5
27
44.5
62.3
104.4
31
52.2
74.5
104.4
1500
2000 or 3000
Slope Compensation
1.5
Slope compensation is applied to guarantee current loop stability when the duty cycle is higher than 50%. For applications
where the duty cycle is smaller than 50%, it is also recommended to apply slope compensation to improve current loop
noise immunity. The minimum and maximum slope compensation values are calculated using the following equation:
V
V
f
C
I
I
RIPPLE
1.6Ω
1.6Ω
OUT
IN SW
SLOPE
OUTMAX
C
SLOPE
800mV −
+
SLOPE
L
25
V
N
2
25
OUT
where:
C
= 5pF
SLOPE
The slope-compensation options of the MAX20812 can be selected by resistor values on PGM1 and PGM2. A higher
slope value is recommended to help reduce duty cycle jittering and improve stability.
Typical Reference Designs
See the Typical Application Circuits for examples of reference schematics. Reference design examples for some common
output voltages are shown in Table 6.
Table 6. Reference Design Examples
I
(A)
PGM1 OR
PGM2
(kΩ)
OUT
(PER
V
(V)
f
R
(kΩ)
R
(kΩ)
PGM0
(kΩ)
L
(μH)
C
(PER EACH
IN
OUT
SW
FB1
FB2
C
OUT
(kHz)
V
PIN)
DDH
PHASE)
0.8
0.9
1.0
1.2
1.8
3.3
5.0
6
6
6
6
6
5
4
750
1.82
2.40
3.01
4.22
7.87
16.9
22.6
3.01
3.01
3.01
3.01
3.01
3.01
2.49
2.49
8.06
8.06
8.06
21.5
30.9
30.9
2.49
2.49
2.49
2.49
2.49
2.15
100
0.47
0.47
0.47
0.56
0.56
1.0
10μF +1μF +0.1μF
10μF +1μF +0.1μF
10μF +1μF +0.1μF
10μF +1μF +0.1μF
10μF +1μF +0.1μF
10μF +1μF +0.1μF
10μF +1μF +0.1μF
3 × 47μF
3 × 47μF
3 × 47μF
3 × 47μF
2 × 47μF
2 × 47μF
1 × 47μF
1000
1000
1000
1500
2000
2000
2.2
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Maxim Integrated | 21
MAX20812
Dual-Output, 6A, 3MHz, 2.7V to 16V, Step-Down
Switching Regulator
PCB Layout Guidelines
•
For electrical and thermal reasons, the second layer from the top and bottom of the PCB should be reserved for power
ground (PGND) planes.
•
•
•
The input decoupling capacitor should be located the closest to the IC and no more than 40 mils from the VDDH_ pins.
The VCC decoupling capacitors should be connected to PGND and placed as close as possible to VCC pin.
An analog ground copper polygon or island should be used to connect all analog control-signal grounds. This “quiet”
analog ground copper polygon or island should be connected to the PGND through a single connection close to the AGND
pin. The analog ground can be used as a shield and ground reference for the control signals (PGM_ and SNSP_).
•
•
The AVDD decoupling capacitors should be connected to AGND and placed as close as possible to AVDD pin.
The boost capacitors should be placed as close as possible to LX_ and BST_ pins on the same side of the PCB as
the IC.
•
The feedback resistor-divider and optional external compensation network should be placed close to the IC to minimize
the noise injection.
•
•
•
The voltage sense line should be shielded by ground plane and be kept away from switching node and the inductor.
Multiple vias are recommended for all paths that carry high currents and for heat dissipation.
The input capacitors and output inductors should be placed near the IC and the traces to the components should be
kept as short and wide as possible to minimize parasitic inductance and resistance.
www.maximintegrated.com
Maxim Integrated | 22
MAX20812
Dual-Output, 6A, 3MHz, 2.7V to 16V, Step-Down
Switching Regulator
Typical Application Circuits
Dual-Output Operation
www.maximintegrated.com
Maxim Integrated | 23
MAX20812
Dual-Output, 6A, 3MHz, 2.7V to 16V, Step-Down
Switching Regulator
Dual-Phase Operation
www.maximintegrated.com
Maxim Integrated | 24
MAX20812
Dual-Output, 6A, 3MHz, 2.7V to 16V, Step-Down
Switching Regulator
Ordering Information
PART NUMBER
MAX20812AFH+
MAX20812AFH+T
MAX20812TAFH+*
MAX20812TAFH+T*
TEMPERATURE RANGE
PIN-PACKAGE
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
21 FC2QFN (exposed top)
21 FC2QFN (exposed top)
21 FC2QFN (closed top)
21 FC2QFN (closed top)
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
*Future product—contact factory for availability.
www.maximintegrated.com
Maxim Integrated | 25
MAX20812
Dual-Output, 6A, 3MHz, 2.7V to 16V, Step-Down
Switching Regulator
Revision History
REVISION
NUMBER
0
REVISION
DATE
PAGES
CHANGED
DESCRIPTION
8/20
Initial release
—
Updated General Description, Benefits and Features, Electrical and Thermal Ratings,
Absolute Maximum Ratings, Package Information, Electrical Characteristics table,
Typical Operating Characteristics, Pin Configurations, Pin Descriptions, Block Diagrams,
Detailed Description, Applications Information, Typical Application Circuits, Ordering
Information table
1, 3–9, 11, 13,
15–16, 18–25
1
3/21
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.
©2021 Maxim Integrated Products, Inc.
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