RT9396 [RICHTEK]
I2C Interface PMIC with 6-Channel WLED Driver and 4-LDO; I2C接口PMIC采用6通道WLED驱动器和4 - LDO
| 型号： | RT9396 |
| 厂家： | 
RICHTEK TECHNOLOGY CORPORATION |
| 描述： | I2C Interface PMIC with 6-Channel WLED Driver and 4-LDO |
| 文件： | 总17页 (文件大小：376K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
RT9396
I2C Interface PMIC with 6-Channel WLED Driver and 4-LDO
General Description
Features
z Tri-Mode (x1/x1.5/x2) Charge Pump
z Maximum 25mA x 6-Channel LED Backlighting
Output Current
The RT9396 is a power management IC (PMIC) for
backlighting and phone camera applications. The PMIC
contains a 6-Channel charge pump white LEDdriver and
four low dropout linear regulators.
z Support Main/Sub (4+2/5+1) LED Function
z 64 Steps Programmable LED Current
z Support PWM Dimming Function
z Fade In/Out Via I2C Control
The charge pump drives up to 6 white LEDs with regulated
constant current for uniform intensity. Each channel
(LED1 to LED6) supports up to 25mA of current. These
6-Channels can be also programmed as 4 plus 2-Channels
or 5 plus 1-Channel with different current setting for
auxiliary LEDapplication. The RT9396 maintains highest
efficiency by utilizing a x1/ x1.5/ x2 fractional charge pump
and low dropout current regulators.An internal 6-bitDAC
is used for backlight brightness control. Users can easily
configure up to 64 steps of LEDcurrent via the I2C interface
control.
z 4 Low Dropout Regulators
z Maximum 200mA x 4-Channel LDO Output Current
z 16-Level LDO Output Voltage Setting
z I2C Programmable Independent LDO Channel
ON/OFF Control
z Over Temperature Protection
z Thin 24-Lead WQFN Package
z RoHS Compliant and Halogen Free
The RT9396 also comprises low noise, low dropout
regulators, which provide up to 200mAof current for each
of the four channels. The four LDOs deliver 3% output
accuracy and low dropout voltage of 200mV @ 200mA.
Users can easily configure LDO output voltage via the I2C
interface control. The LDOs also provide current limiting
and over temperature functions.
Applications
z Cellular Phones
z PDAs and Smart Phones
Pin Configurations
(TOP VIEW)
The RT9396 is available in a WQFN-24L 3x3 package.
24 23 22 21 20 19 18
1
2
3
17
16
15
PGND
C2N
C1N
C1P
SCL
SDA
EN
PWM
CF
Ordering Information
RT9396
4
5
14
13
Package Type
C2P
QW : WQFN-24L 3x3 (COL) (W-Type)
6
7
8
9
10 11 12
Lead Plating System
G : Green (Halogen Free and Pb Free)
Note :
WQFN-24L 3x3 (COL)
Richtek products are :
ꢀRoHS compliant and compatible with the current require-
ments of IPC/JEDEC J-STD-020.
ꢀSuitable for use in SnPb or Pb-free soldering processes.
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RT9396
Marking Information
JP= : Product Code
YMDNN : Date Code
JP=YM
DNN
Typical Application Circuit
C
FLY2
C
FLY1
1µF
1µF
4
3
5
2
C1P C1N C2P C2N
7
WLED
VIN
V
BAT
C
2.2µF
23
22
IN1
LED1
LED2
RT9396
8
LDOIN
CF
21
20
19
18
24
12
LED3
LED4
LED5
LED6
C
2.2µF
IN2
13
C
1µF
F
Chip Enable
15
17
16
VOUT
LDO1
LDO2
LDO3
LDO4
EN
C
OUT
SCL
SDA
C
11
10
9
L1
1µF
2
I C
C
L2
1µF
1µF
C
14
L3
PWM
PWM
C
1µF
L4
AGND
PGND
1µF
6
1
Timing Diagram
2
010
LED<1:6>
On/Off
I C
01011111
00000000
00000000
Reg. Addr.
6CH PWM Mode
2
I C
Main BL
01111101
Fade in/out time = 8ms/step, I
[1~6] = 62/64 x 25mA
LED
Reg. Data
Current Level
Internal
PWMEN Reg.
PWM control Backlight
PWM Dimming
Note:
T
= 16ms
SHD
PWM signal rise after
internal PWMEN is
enabled
PWM Pin
T
> 0.5µs
0.5µs < T < 500µs
Hi
LO
Main I
[1:6]
LED
I
[1~6] Current =
LED
62/64 x 25mA x PWM Duty
Fade in
time
0
Time (s)
Figure 1. TimingDiagram
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16-step Voltage
Setting
LDO
Address
Channel
Selection
• I2C Writing Cycles of LDOX
Start
ON/OFF
1
0
1
0
1
0
0
0
0
0
1
B4 B3 B2 B1 B0
0
0
0
0
C3 C2 C1 C0
Stop
• I2C Writing Cycles of Backlighting I (LED1~6)
Backlight
Address
Channel
ON/OFF
Fade In/Out
Setting
64-step Current Setting
Start
1
0
1
0
1
0
0
0
0
1 0B4 B3 B2 B1 B0
C7 C6 C5 C4 C3 C2 C1 C0
Stop
Fade In/Out Setting:
01: Every Step of Fade In/Out = 8 ms
10: Every Step of Fade In/Out = 16 ms
11: Every Step of Fade In/Out = 32 ms
• I2C Writing Cycles of Backlighting II (Main: LED1~5, Sub: LED6)
Backlight
Address Main
Channel
ON/OFF
Fade In/Out
Setting
Main 64-step Current Setting
Start
1
0
1
0
1
0
0
0
0
1 10B3 B2 B1 B0
C7 C6 C5 C4 C3 C2 C1 C0
Stop
Main Fade In/Out Setting:
01: Every Step of Fade In/Out = 8 ms
10: Every Step of Fade In/Out = 16 ms
11: Every Step of Fade In/Out = 32 ms
Backlight
Address
Channel
ON/OFF
Fade In/Out
Setting
Sub 64-step Current Setting
Sub
Start
1
0
1
0
1
0
0
0
0
1 11000B0
C7 C6 C5 C4 C3 C2 C1 C0
Stop
Sub Fade In/Out Setting:
01: Every Step of Fade In/Out = 8 ms
10: Every Step of Fade In/Out = 16 ms
11: Every Step of Fade In/Out = 32 ms
• I2C Writing Cycles of Backlighting III (Main: LED1~4, Sub: LED5~6)
Backlight
Channel
ON/OFF
Fade In/Out
Setting
Main 64-step Current Setting
Address Main
Start
1
0
1
0
1
0
0
0
1
0
00B2 0B1 B0
C7 C6 C5 C4 C3 C2 C1 C0
Stop
Main Fade In/Out Setting:
01: Every Step of Fade In/Out = 8 ms
10: Every Step of Fade In/Out = 16 ms
11: Every Step of Fade In/Out = 32 ms
Backlight
Address
Channel
ON/OFF
Fade In/Out
Setting
Sub 64-step Current Setting
Sub
Start
1
0
1
0
1
0
0
0
1
0
01000B0
C7 C6 C5 C4 C3 C2 C1 C0
Stop
Sub Fade In/Out Setting:
01: Every Step of Fade In/Out = 8 ms
10: Every Step of Fade In/Out = 16 ms
11: Every Step of Fade In/Out = 32 ms
Figure 2. Control Sequences of LDO Setting and LEDDimming
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RT9396
Functional Pin Description
Pin No.
Pin Name
PGND
C2N
Pin Function
1
2
Charge Pump Ground.
Fly Capacitor 2 Negative Connection.
Fly Capacitor 1 Negative Connection.
Fly Capacitor 1 Positive Connection.
Fly Capacitor 2 Positive Connection.
Ground for LDO1 to LDO4.
3
C1N
4
C1P
5
C2P
6
AGND
VIN
7
Charge Pump Power Input. Connect this pin to LDOIN pin.
LDO Power Input. Connect this pin to VIN pin.
LDO4 Output.
8
LDOIN
LDO4
LDO3
LDO2
LDO1
CF
9
10
11
12
13
14
15
LDO3 Output.
LDO2 Output.
LDO1 Output.
PWM Filter Capacitor Connection.
PWM Dimming Control Input.
Chip Enable (Active High).
PWM
EN
16
17
SDA
SCL
I2C Data Input.
I2C Clock Input.
18
19
20
21
22
23
24
LED6
LED5
LED4
LED3
LED2
LED1
VOUT
Current Sink for LED6.
Current Sink for LED5.
Current Sink for LED4.
Current Sink for LED3.
Current Sink for LED2.
Current Sink for LED1.
Charge Pump Output. Connect a 1μF ceramic capacitor between VOUT and GND.
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Function Block Diagram
x1/x1.5/x2
Charge Pump
VOUT
VIN
1MHz
Oscillator
OVP
Gate Driver
Mode
Decision
Soft Start
LED1
LED2
LED3
LED4
LED5
LED6
PWM
Dimming
CF
Current Setting
Shutdown
Delay
PWM
Current Source
LED
Ctrl.
OR
Gate
OTP &
Current Bias
V
OUT
LDO
Ctrl.
SDA
SCL
2
I C
EN
LDOIN
POR
LDOIN
BandGap
Reference
-
+
LDO1 to
LDO4
AGND
PGND
RES Divider
Voltage Setting
x4
Table 1. 16-Step LDO Output Voltage Setting
LDO3 & LDO4
LDO1 &
C3 C2 C1 C0 LDO2 Output
Voltage (V)
LDO1 &
LDO3 & LDO4
Output
Voltage (V)
Output
C3 C2 C1 C0 LDO2 Output
Voltage (V)
Voltage (V)
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
1
1.1
1.2
1.4
1.7
1.8
1.9
2
1
1
1
1
1
1
1
1
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
2.5
2.6
2.7
2.8
2.9
3
2.2
2.3
2.4
2.5
2.8
2.85
3.2
3.3
1.1
1.2
1.3
1.5
1.6
1.8
2.1
3.1
3.3
2.1
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RT9396
Table 2. 64-Step WLED Current Setting
WLED
WLED
Current (mA)
C5
C4
C3
C2
C1
C0
C5
C4
C3
C2
C1
C0
Current (mA)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0.39
1
0
0
0
0
0
12.89
0.78
1.17
1.56
1.95
2.34
2.73
3.13
3.52
3.91
4.3
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
1
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
13.28
14.06
14.45
14.84
15.23
15.63
16.02
16.41
16.8
17.19
17.58
17.97
18.36
18.75
19.14
19.53
19.92
20.31
20.7
4.69
5.08
5.47
5.86
6.25
6.64
7.03
7.42
7.81
8.2
21.09
21.48
21.88
22.27
22.66
23.05
23.44
23.83
24.22
24.61
25
8.59
8.98
9.38
9.77
10.16
10.55
10.94
11.33
11.72
12.11
12.5
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RT9396
Absolute Maximum Ratings (Note 1)
z Supply Input Voltage, VIN ---------------------------------------------------------------------------------------------- −0.3V to 6V
z Output Voltage, VOUT----------------------------------------------------------------------------------------------------------------------------------------------- −6V to 0.3V
z Other Pins ----------------------------------------------------------------------------------------------------------------- −0.3V to 6V
z PowerDissipation, PD @ TA = 25°C
WQFN-24L 3x3 ----------------------------------------------------------------------------------------------------------- 1.667W
z Package Thermal Resistance (Note 2)
WQFN-24L 3x3, θJA ----------------------------------------------------------------------------------------------------- 60°C/W
z Junction Temperature --------------------------------------------------------------------------------------------------- 150°C
z Lead Temperature (Soldering, 10 sec.) ----------------------------------------------------------------------------- 260°C
z StorageTemperature Range ------------------------------------------------------------------------------------------- −65°C to 150°C
z ESD Susceptibility (Note 3)
HBM (Human Body Mode) --------------------------------------------------------------------------------------------- 2kV
MM (Machine Mode) ---------------------------------------------------------------------------------------------------- 200V
Recommended Operating Conditions (Note 4)
z Supply Input Voltage, VIN, VLDOIN ------------------------------------------------------------------------------------ 2.8V to 5V
z Junction Temperature Range ------------------------------------------------------------------------------------------ −40°C to 125°C
z Ambient Temperature Range ------------------------------------------------------------------------------------------ −40°C to 85°C
Electrical Characteristics
(VIN = VLDOIN = 3.6V, CIN = 2.2μF, COUT = 1μF, CFLY1 = CFLY2 = 1μF, VF = 3.5V, ILEDx = 25mA, TA = 25°C, unless otherwise
specification)
Parameter
Symbol
Test Conditions
Rising.
IN
Min
Typ
Max Unit
Input Power Supply
Under-Voltage Lockout Threshold
V
V
1.8
--
2.1
2.5
--
V
UVLO
Under-Voltage Lockout Hysteresis ΔV
200
mV
UVLO
x1 Mode, V = 5V, No Load,
LDO[1:4] OFF
IN
Quiescent of x1 Mode
Quiescent of x2 Mode
I
--
1
2
mA
Q_x1
x2 Mode, V = 3.5V, No Load,
IN
I
I
--
--
3.5
0.5
5
1
mA
Q_x2
LDO[1:4] OFF
Shutdown Current
V
= 5V, V = 0V
μA
SHDN
IN
EN
Charge Pump WLED Driver
Backlight I
Accuracy
−5
−3
--
0
0
5
3
%
%
LEDx
Backlight Current Matching
Dropout Voltage
70
--
mV
Charge Pump
Oscillator Frequency
--
--
1000
3.6
--
kHz
V
x1 Mode to x1.5 Mode
Transition Voltage (V falling)
V = 3.5V, I
= 150mA
= 150mA
3.75
f
OUT
IN
Mode Transition Hysteresis
Over Voltage Protection
V = 3.5V, I
--
250
5.5
--
mV
V
f
OUT
V
= 4.5V
5.2
5.8
IN
To be continued
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RT9396
Parameter
Symbol
Test Conditions
Min
Typ Max Unit
LDO1 to LDO4
Input Voltage
V
V
= 2.8V to 5V
2.8
--
--
--
5
V
IN
IN
Dropout Voltage
≥ 2.8V, I
= 200mA
200 mV
OUT
2
Output voltage Range
VOUT Accuracy
By I C Setting
1.1
--
3.3
3
V
I
= 1mA
−3
%
OUT
V
V
= (V
+ 0.3V) to 5V or
IN
IN
OUT
Line Regulation
--
--
0.2 %/V
0.6
600 mA
> 2.5V, whichever is larger
Load Regulation
1mA < I
< 200mA
--
230
--
--
%
OUT
Current Limit
I
I
I
R
= 1Ω
LOAD
350
140
--
LIM
Q
Quiescent Current
Shutdown Current
Thermal Shutdown
Thermal Shutdown Hysteresis
4-Channel All Turn On
200
1
μA
μA
°C
°C
--
SHDN
T
--
160
20
--
SD
ΔT
--
--
SD
2
I C interface
EN, SDA,SCL Pull Low Current
I
--
1.4
--
5
--
--
--
--
--
--
--
--
10
--
μA
V
EN
Logic-High
Logic-Low
V
EN, SDA, SCL
Threshold Voltage
IH
V
V
0.4
0.4
V
IL
SDA Output Low Voltage
SCL Clock Frequency
--
V
CL
f
t
t
t
t
t
t
t
--
400 kHz
SCL
Low
High
HD_STR
SCL Clock Low Period
1.3
0.6
0.6
0.6
--
--
μs
μs
μs
μs
ns
μs
μs
SCL Clock High Period
Hold Time START Condition
Setup Time for Repeat START
SDA Data Setup Time
--
--
SU_STR
SU_DAT
HD_DAT
100
0.05
0.6
--
--
--
--
SDA Data HOLD Time
0.9
--
Setup Time for STOP Condition
SU_STO
BUF
Bus Free Time Between STOP and
START Condition
t
1.3
--
--
μs
PWM Dimming Control
PWM Dimming Frequency
1
--
200 kHz
PWM Dimming High Time
PWM Dimming Low Time
Shutdown Delay
0.5
0.5
16
--
--
--
--
500
--
μs
μs
ms
Note 1. Stresses listed as the above “Absolute Maximum Ratings” may cause permanent damage to the device. These are for
stress ratings. 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 remain possibility to affect device reliability.
Note 2. θJA is measured in the natural convection at TA = 25°C on a high effective thermal conductivity four-layer test board of
JEDEC 51-7 thermal measurement standard.
Note 3. Devices are ESD sensitive. Handling precaution is recommended.
Note 4. The device is not guaranteed to function outside its operating conditions.
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Typical Operating Characteristics
For Charge Pump
Efficiency vs. Input Voltage
LED Current vs. Input Voltage
100
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15
90
80
70
60
50
40
30
20
LED1
LED2
LED3
LED4
LED5
LED6
10
Vf = 3.5V, ILEDx = 25mA
Vf = 3.5V
5.5
0
2.5
3
3.5
4
4.5
5
5.5
2.5
3
3.5
4
4.5
5
Input Voltage (V)
Input Voltage (V)
x1 Mode Quiescent Current vs. Input Voltage
3.0
x2 Mode Quiescent Current vs. Input Voltage
6.0
5.5
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
2.5
2.0
1.5
1.0
0.5
0.0
2.5
3
3.5
4
4.5
5
5.5
2.5
3
3.5
4
4.5
5
5.5
Input Voltage (V)
Input Voltage (V)
Shutdown Current vs. Input Voltage
x2 Mode Inrush Current Response
0.650
0.625
0.600
0.575
0.550
VOUT
(1V/Div)
C1P
(2V/Div)
IIN
(500mA/Div)
VIN = 2.8V, Vf = 3.5V, ILEDx = 25mA
2.5
3
3.5
4
4.5
5
5.5
Time (100μs/Div)
Input Voltage (V)
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RT9396
Ripple & Spike
x1.5 Mode Inrush Current Response
VOUT
(20mV/Div)
VOUT
(1V/Div)
VIN
(20mV/Div)
C1P
(2V/Div)
VC1P
(2V/Div)
IIN
(200mA/Div)
VIN = 3V, Vf = 3.5V, ILEDx = 25mA
VIN = 3.35V, Vf = 3.5V, ILEDx = 25mA
Time (500ns/Div)
Time (100μs/Div)
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RT9396
For LDO
Output Voltage vs. Temperature
Dropout Voltage vs. Load Current
3.34
250
200
150
100
50
3.33
3.32
3.31
3.30
3.29
3.28
LDO2
LDO3
LDO1
LDO4
LDO1
LDO3
LDO4
LDO2
VIN = 4.3V, VLDO = 3.3V
0
-50
-25
0
25
50
75
100
125
0
50
100
150
200
250
Temperature (°C)
Load Current (mA)
Power On
Power On
SCL
(5V/Div)
SCL
(5V/Div)
VLDO1
VLDO3
(2V/Div)
(2V/Div)
VLDO2
(2V/Div)
VLDO4
(2V/Div)
IIN
IIN
(500mA/Div)
(500mA/Div)
VIN = 4.3V, VLDO1 = VLDO2 = 3.3V, ILOAD = 200mA
VIN = 4.3V, VLDO3 = VLDO4 = 3.3V, ILOAD = 200mA
Time (25μs/Div)
Time (25μs/Div)
Line Transient Response
Line Transient Response
4.8
4.8
VIN
(V)
VIN
(V)
3.8
3.8
VLDO4
VLDO2
(20mV/Div)
(20mV/Div)
VLDO3
VLDO1
(20mV/Div)
(20mV/Div)
VIN = 3.8V to 4.8V
VIN = 3.8V to 4.8V
VLDO3 = VLDO4 = 2.8V, ILOAD = 200mA
VLDO1 = VLDO2 = 2.8V, ILOAD = 200mA
Time (100μs/Div)
Time (100μs/Div)
DS9396-01 April 2011
www.richtek.com
11
RT9396
Load Transient Response
Load Transient Response
VLDO3
VLDO1
(100mV/Div)
(100mV/Div)
ILDO3
(200mA/Div)
ILDO1
(200mA/Div)
VLDO4
VLDO2
(100mV/Div)
(100mV/Div)
ILDO4
(200mA/Div)
ILDO2
(200mA/Div)
VIN = 4.3V, VLDO3 = VLDO4 = 3.3V
VIN = 4.3V, VLDO1 = VLDO2 = 3.3V
Time (10μs/Div)
Time (10μs/Div)
Noise
PSRR
20
10
0
-10
-20
-30
-40
-50
-60
-70
-80
-90
(0.2mV/Div)
VIN = 4.3V, VLDO = 3.3V, No Load
Time (50ms/Div)
VIN = 4.3V, VLDO = 3.3V, ILOAD = 200mA
-100
10
100
1000
10000
100000 1000000
Frequency (Hz)
Noise
(0.2mV/Div)
VIN = 4.3V, VLDO = 3.3V, ILOAD = 50mA
Time (50ms/Div)
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12
DS9396-01 April 2011
RT9396
Applications Information
The RT9396 is an I2C interface PMIC with one 6-Channel
charge pump white LEDdriver and four LDOs. The charge
pump provides 6-Channel low dropout voltage current
source to regulate up to 6 white LEDs. For high efficiency,
the RT9396 implements a smart mode transition for charge
pump operation. The four LDOs are capable of delivering
low dropout voltage of 200mV @ 200mA with 3% output
accuracy. The I2C dimming function allows for a 64 steps
LEDbrightness control and 16 steps LDO voltage control.
EN
……………
SDA
SCL
……………
Figure 3. The Power Sequence
I2C Compatible Interface
Figure 4 shows the timing diagram of the I2C interface.
The RT9396 communicates with a host (master) using
the standard I2C 2-wire interface. The two bus lines of
SCL and SDA must be pulled high when the bus is not in
use. Internal pull-up resistors are installed.After the START
condition, the I2C master sends 8-bits data, consisting of
seven address bits and a following data direction bit (R/
W). The RT9396 address is 1010100 (54h) and is a receive-
only (slave) device. The second word selects the register
to which the data will be written. The third word contains
data to write to the selected register.
Input UVLO
An under voltage lockout (UVLO) function is provided to
prevent unstable occurrences during start-up. The UVLO
threshold is set at an input rising voltage of 2.1V typically
with a hysteresis of 0.2V. The input operating voltage range
of the RT9396 is from 2.8V to 5V.An input capacitor should
be placed near the VIN pin to reduce ripple voltage. It is
recommended to use a ceramic 2.2μF or larger capacitance
as the input capacitor.
Figure 2 shows the writing information for voltage of the
four LDOs and current of the six LEDs. In the second
word, the sub-address of the four LDOs is “001” and the
sub-address of the LEDDriver for different dimming modes
are respectively “010”, “011” and “100”. For the LDO
output voltage setting, bits B1 to B4 represent each LDO
channel respectively where a “1” indicates selected and
a “0” means not selected. The B0 bit controls on/off (1/
0) mode for the selected LDO channel(s). Then, in the
third word, bits C0 to C3 control a 16-step setting of LDO1
to LDO4. The voltage values are listed in Table 1.
Soft-Start
The RT9396 includes a soft-start circuit to limit the inrush
current at power on and mode switching. The soft-start
circuit limits the input current before the output voltage
reaches a desired voltage level.
Mode Decision
The RT9396 uses a smart mode decision method to
choose the working mode for maximum efficiency. The
charge pump can operate at x1, x1.5 or x2 mode. The
mode decision circuit senses the output voltage and LED
voltage to determine the optimum working mode.
For LED dimming, there are three operating modes
(Backlight I, Backlight II and Backlight III) to select from
by writing respectively “010”, “011” and “100” into the
first three bits of the second word. When Backlight I is
selected, all six LEDs have the same behavior. Their 64-
step dimming currents are set by bits C0 to C5, which
are listed in Table 2. The bits C6 and C7 determine the
fade in/out time of each step as shown in Figure 2. For
Backlight II and Backlight III, two sets of LEDs, called
main and Sub, can work separately and turn on solely. It
should be noticed that no matter which mode is selected,
the B0 bit must be a “1” in order for te LEDs in the main
set to be turned on.
Power Sequence
In order to assure normal operating condition, the input
voltage and ENshould be active before the RT9396 receives
the I2C signal, as shown in Figure 3. The RT9396 can be
shut down by pulling EN low. When EN is reset, the I2C
signal also needs to be re-applied to resume normal
operating condition.
DS9396-01 April 2011
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13
RT9396
In Backlight II, the main set consists of LED1 to LED5
and LED6 is the Sub set. In Backlight III, the main set
consists of LED1 to LED4, while the Sub set comprises
of LED5 and LED6. The RT9396 has another dimming
function called PWM dimming, which can be enabled by
selecting the B4 bit in Backlight I, B3 bit in Backlight II,
and B2 bit in Backlight III. Once the function is enabled, a
PWM signal is applied to the PWM pin to perform PWM
dimming. The LED current value is the current value set
by C0 to C5 multiplied by the duty cycle. It is important to
note that the PWM dimming function applies only to the
main set.
The 2nd Word (Sub
Address, Data)
The 1st Word (Chip
Address, R/W)
The 3rd Word (data)
Channel
Sub
Adress selection
I2C Address
R/W
Test Mode
Data II
ON/OFF
Start
S
A6A5A4A3A2A1A0 0
B7B6B5B4B3B2B1B0
C7C6C5C4C3C2C1C0
Stop
4
P
SCL
SDA
1
2
3
4
5
6
7
8
9
1
2
3
4
5
6
7
8
9
1
2
3
5
6
7
8
9
0
A6 A5 A4 A3 A2 A1 A0 0 ACK B7 B6 B5 B4 B3 B2 B1 B0 ACK C7 C6 C5 C4 C3 C2 C1 C0 ACK
S
= Start Condition
W
R
= Write (SDA =“0＂)
= Read (SDA =“1＂)
ACK = Acknowledge
= Stop Condition
P
Figure 4. I2C Communication Sequence
capacitance larger than 1μF is placed close to the RT9396
supply input to reduce ripple. The value of this capacitor
can be increased without limit. The input capacitor must
be located at a distance of not more than 0.5 inch away
from the input pin of the IC and tied to a clean analog
ground. Any good quality ceramic or tantalum capacitor
can meet the requirement. The capacitor with larger value
and lower ESR (equivalent series resistance) provides
better PSRR power supply rejection ratio and line-transient
response. The output capacitor must meet minimum
requirement for both capacitance and ESR in all LDO's
applications. For stability consideration, a ceramic
capacitor with minimum capacitance of 1μF and minimum
ESR of 20mΩ is recommended for the output capacitor.
For space-saving and performance consideration, the
RT9396 is designed to work with ceramic capacitor of low
ESR. However, because of it's wide ESR range tolerance,
the RT9396 can work stably with output capacitor of other
types as well. Figure 5 shows the stable region for various
load current and output capacitor conditions. Large output
capacitance can reduce noise and improve load transient
response, stability, and PSRR. The capacitor must be
located at a distance not more than 0.5 inch away from
the VOUT pin and tied to a clean analog ground.
Flying Capacitors Selection
To attain better performance of the RT9396, the selection
of peripherally appropriate capacitor and value is very
important. These capacitors determine some parameters
such as input/output ripple voltage, power efficiency and
maximum supply current by charge pump. To reduce the
input and output ripple effectively, low ESR ceramic
capacitors are recommended. For LEDdriver applications,
the input voltage ripple is more important than the output
voltage ripple. The input ripple is influenced by the input
capacitor, CIN. Increasing the input capacitance can further
reduce the ripple. The flying capacitors ,CFLY1 and CFLY2
determine the supply current capability of the charge pump,
which in turn influences the overall efficiency of the system.
Alower capacitance will improve efficiency, but it will limit
the LED's current at low input voltage. For a 6 x 25mA
load over the entire input voltage range of 2.8V to 5V, it is
recommended to use a 1μF ceramic capacitor for CFLY1
CFLY2 and COUT
,
.
LDO Capacitor Selection
Like for any low dropout regulator, the external capacitors
used for the RT9396 must be carefully selected for
regulator stability and performance. A capacitor with
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14
DS9396-01 April 2011
RT9396
Region of Stable COUT ESR vs. Load Current
2.00
1.75
1.50
1.25
1.00
0.75
0.50
0.25
0.00
100
Four- Layer PCB
VIN = 5V
IN = COUT1
COUT2 = 1uF/X7R
C
=
10
1
Unstable Range
Stable Range
0.1
0.01
0.001
Simulation Verify
0
25
50
75
100
125
0
50
100
150
200
250
300
Ambient Temperature (°C)
Load Current (mA)
Figure 5. Stable COUT ESR Range
Figure 6.Derating Curve for RT9396 Package
Thermal Considerations
Layout Considerations
For continuous operation, do not exceed absolute
maximum junction temperature. The maximum power
dissipation depends on the thermal resistance of IC
package, PCB layout, rate of surrounding airflow and
temperature difference between junction to ambient. The
maximum power dissipation can be calculated by following
the formula :
The RT9396 is a high-frequency switched-capacitor
converter. For best performance, careful PCB layout is
necessary. Place all peripheral components as close as
possible to the IC. Place CIN1, CIN2, COUT, CL1, CL2, CL3,
CL4, CFLY1, and CFLY2 near to VIN, LDOIN, VOUT, LDO1,
LDO2, LDO3, LDO4, C1P, C1N, C2P, C2N, andGNDpin
respectively. Ashort connection is highly recommended.
The following guidelines should be strictly followed when
designing a PCB layout for the RT9396.
P
D(MAX) = (TJ(MAX) − TA ) / θJA
Where TJ(MAX) is the maximum junction temperature, TAis
the ambient temperature and θJAis the junction to ambient
thermal resistance.
ꢀ The exposed GND pad must be soldered to a large
ground plane for heat sinking and noise prevention. The
through-hole vias located at the exposed pad is
connected to the ground plane of internal layer.
For recommended operating conditions specification of
the RT9396, the maximum junction temperature is 125°C
and TA is the ambient temperature. The junction to ambient
thermal resistance θJA is layout dependent. For
WQFN-24L 3x3 package, the thermal resistance θJA is
60°C/W on the standard JEDEC 51-7 four-layer thermal
test board. The maximum power dissipation at TA = 25°C
can be calculated by the following formula :
ꢀ
VIN traces should be wide enough to minimize
inductance and handle high currents. The trace running
from the battery to the IC should be placed carefully
and shielded strictly.
ꢀ Input and output capacitors must be placed close to the
IC. The connection between pins and capacitor pads
should be copper traces without any through-hole via
connection.
PD(MAX) = (125°C − 25°C) / (60°C/W) = 1.667W for
WQFN-24L 3x3 package
ꢀ The flying capacitors must be placed close to the IC.
The traces running from the pins to the capacitor pads
should be as wide as possible. Long traces will also
produce large noise radiation caused by the large dv/dt
on these pins. Short trace is recommended.
The maximum power dissipation depends on operating
ambient temperature for fixed TJ(MAX) and thermal
resistance θJA. For RT9396 package, the derating curve
in Figure 6 allows the designer to see the effect of rising
ambient temperature on the maximum power dissipation
allowed.
DS9396-01 April 2011
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15
RT9396
ꢀ All the traces of LEDs and VIN running from pins to
LCM module should be shielded and isolated by the
ground plane. The shielding prevents the interference of
high frequency noise coupled from the charge pump.
Output capacitor must be placed between
GND and VOUT to reduce noise coupling
from charge pump to LEDs.
GND
GND
The flying capacitors
must be placed close
to the IC.
24 23 22 21 20 19 18
1
2
3
4
5
17
16
15
14
13
PGND
C2N
C1N
C1P
SCL
SDA
EN
PWM
CF
VIN traces should
be wide enough.
C2P
6
7
8
9
10 11 12
GND
Battery
GND
Input capacitors must be
placed close to the IC.
Figure 7. PCB LayoutGuide
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16
DS9396-01 April 2011
RT9396
Outline Dimension
Dimensions In Millimeters
Dimensions In Inches
Symbol
Min
Max
0.800
0.050
0.250
0.250
3.100
3.100
Min
Max
A
A1
A3
b
0.700
0.000
0.175
0.150
2.900
2.900
0.028
0.000
0.007
0.006
0.114
0.114
0.031
0.002
0.010
0.010
0.122
0.122
D
E
e
0.400
0.016
L
0.350
0.950
0.450
1.050
0.014
0.037
0.018
0.041
L1
W-Type 24L QFN 3x3 (COL) Package
Richtek Technology Corporation
Headquarter
Richtek Technology Corporation
Taipei Office (Marketing)
5F, No. 20, Taiyuen Street, Chupei City
Hsinchu, Taiwan, R.O.C.
5F, No. 95, Minchiuan Road, Hsintien City
Taipei County, Taiwan, R.O.C.
Tel: (8863)5526789 Fax: (8863)5526611
Tel: (8862)86672399 Fax: (8862)86672377
Email: marketing@richtek.com
Information that is provided by Richtek Technology Corporation is believed to be accurate and reliable. Richtek reserves the right to make any change in circuit
design, specification or other related things if necessary without notice at any time. No third party intellectual property infringement of the applications should be
guaranteed by users when integrating Richtek products into any application. No legal responsibility for any said applications is assumed by Richtek.
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