RT4832A
Sub PMIC with Dual-Output Boost Converter with I2C
Interface for Flash LED and Backlight LED, Dual-Output LCD
Bias and DSV
General Description
The RT4832A is an integrated total power solution for
Flash LED Driver, Backlight WLED Driver, and DSV
Driver. Flash LED Driver provides up to 2-CH 1.5A
applications. Back Light WLED Driver supports up to
36V output for 10 WLEDs applications. And it provides
1024 steps LED current with logarithmic/linear curve.
DSV is implemented by one single inductor boost and
inverting charge pump, which provide customers
minimum EVB area compared to dual inductors. The
negative output power (CPOUT) comes from boost
output (LCMOUT). It also provides DSV positive
voltage (POS), which power noise is reduce by passing
though LDO. Their ranges can be programmed from
±4V to ±6V per 50mV step respectively. Flash Boost
Converter operates at 2MHz/4MHz frequency. The
4MHZ frequency solution allows tinny and low-profile
components. Torch Mode Current can be set from
Features
25mA to 375mA per 25mA step. And Strobe Mode
Current range is from 100mA to 1.5A per 100mA step.
DSV drives TFT-LCD panels up to 10” (from SFF to
MFF like tablets). These two output rails are usually
connected to Source Driver IC. Wide input voltage
range from 2.5V to 5.5V optimizes the single-cell
battery applications (Li-Ion, Ni-Li, Li-Polymer) and
which symmetrical output current is up to 80mA.
The RT4832A provides complete protection such as
VIN under voltage lockout, Vin monitor protection, over
current protection, over voltage protection, LED short
protection, VOUT short protection and over
temperature protection.
The RT4832A is available in WL-CSP-30B 2.24x2.64
(BSC) package.
Applications
Smart Phones
Probable Instruments
Copyright © 2017 Richtek Technology Corporation. All rights reserved.
DS4832A-00
January 2017
Input Voltage Range : 2.5V to 5.5V
Internal Soft-start, UVLO, OTP, OCP
Typical Shutdown Current : < 1A
40 to 85°C Temperature Range
2CH Back Light LED Driver
Drives Up to 10 WLEDs in Two Strings
2
External PWM Pin Control and I C
Programmable 11 bit Linear and Exponential
Brightness
LED Current Accuracy 5% (>500A), 3%
(>5mA)
2
I C Programmable OVP 18/22/25/29/33/36V
2CH Flash LED Driver
Torch Mode Current from 25mA to 375mA per
25mA Step with 2 Channels
Strobe Mode Current from 100mA to 1.5A per
100mA Step with 2 Channels
2
I C Programmable Flash Safety Timer from
32ms to 1024ms per 32ms Step
High Accurate Safety Timer ±10%, Current
Accuracy 4% (>375mA), Current Matching
7% (>375mA)
VIN Monitor Protection from 2.5V to 3.2V per
0.1V Step
Selectable Input Current Limit 1.9/2.8A
2MHz/4MHz Switching Frequency for Flash LED
Flash LED1/2 Short Protection, and Output
Short Protection
Txmask Protection by Independent Pin
DSV
2
I C Programmable Output Voltages
Flexible Boost Voltage, POS, CPOUT Default
Setting
Regulated Voltage Output : 4V to 6V per 50mV
Step
Positive Voltage Output : 4 to 6V per 50mv Step
Negative Voltage Output : 4 to 6V per 50mV
Step
User Selectable Output Fast Discharge Mode or
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RT4832A
Float Mode when Turned Off
Independent Positive and Negative Enable
Control by Two External Pins
Marking Information
True Load Disconnect, OCP, and
Positive/Negative SCP Function
0X : Product Code
YMDNN : Date Code
0X YM
DNN
Ordering Information
Pin Configuration
RT4832A
Package Type
WSC : WL-CSP-30B 2.24x2.64 (BSC)
(TOP VIEW)
Note :
A1
POS
Richtek products are :
RoHS compliant and compatible with the current
A3
A4
A5
LCM
SW
LED
GND
LED
SW
B1
B2
B3
B4
B5
ENM
ENP
EN
LCM
GND
LED
OUT
requirements of IPC/JEDEC J-STD-020.
A2
LCM
OUT
Suitable for use in SnPb or Pb-free soldering processes.
C1
C2
C3
C1
SDA
Txmask
D1
D2
D3
D4
D5
CP
GND
C4
AGND
C5
LED1
STRB
PWM
LED2
E1
E2
E3
E4
E5
C2
Flash
LED
Flash
OUT
Flash
SW
VIN
SCL
F1
F2
F3
CP
OUT
Flash
LED
Flash
OUT
F4
Flash
SW
F5
Flash
GND
WL-CSP-30B 2.24x2.64 (BSC)
Typical Application Circuit
L2
10μH
D1
L1
0.47μH to 1μH
E5
B3
D4
D3
C3
D2
C2
FlashSW
VIN
EN
PWM
STRB
Txmask
SCL
SDA
B2
ENP
B1
ENM
L3
2.2μH
A3 LCMSW
C2
4.7μF
C1
E1
C1
LCMOUT A2
POS
FlashLED
F1 CPOUT
C6
10μF
Copyright © 2017 Richtek Technology Corporation. All rights reserved.
AGND
FlashGND
C2
2P10S
WLEDs
LED1 C5
D5
LED2
FlashOUT E3, F3
LEDGND
C5
10μF
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LEDSW A5
LEDOUT B5
……
E4, F4
C1
10μF
VIN
C8
2.2μF
RT4832A
……
VIN
LED1
CPGND
C3
10μF
C7
10μF
A1
E2, F2
A4
C4
10μF
C4
F5
D1
LCMGND B4
U1
is a registered trademark of Richtek Technology Corporation.
DS4832A-00
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RT4832A
Reference
Part Number
Value
Description
C1, C3, C4,
C5, C6, C7
C2012X7R1A106KT0AHE
10F/10V/X5R
Ceramic capacitor
C2
C2012X7R1A475KT0AHE
4.7F/10V/X5R
Ceramic capacitor
C8
UMK316BJ225KD-T
2.2F/50V/X7R
Ceramic capacitor
L1
NR4018T1R0N
1H
Inductor
L2
NR4018T100M
10H
Inductor
L3
NR4018T2R2M
2.2H
Inductor
D1
SS14
40V/1A
Schottky diode
Timing Diagram
SDA
VIH( MIN)
VIL( MAX)
tSU, DAT
tLOW
SCL
tHD, DAT
tHIGH
tSU, STO
tBUF
VIH( MIN)
VIL( MAX)
tHD, STA
tf
S
Copyright © 2017 Richtek Technology Corporation. All rights reserved.
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January 2017
P
S
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RT4832A
Functional Pin Description
Pin No.
Pin Name
Pin Function
A1
POS
Positive terminal LDO output. Connect a 10F ceramic capacitor between this
pin and Ground.
A2
LCMOUT
DSV boost converter output pin. Connect a 10F ceramic capacitor between this
pin and Ground.
A3
LCMSW
Switching node of DSV boost converter. Connect a 2.2μH inductor between
LCMSW and VIN.
A4
LEDGND
Back light LED ground.
A5
LEDSW
Switch node of boost converter. Connect a 4.7H to 10H inductor between
LEDSW and VIN.
B1
ENM
Enable the CPOUT.
B2
ENP
Enable the POS.
B3
EN
Chip enable.
B4
LCMGND
DSV boost converter ground pin.
B5
LEDOUT
Back light LED boost output pin.
C1
C1
Fly capacitor 1 positive connection of inverter charge pump.
C2
SDA
I2C serial data input/output. An external pull-up resistor is required.
C3
Txmask
Configurable power amplifier synchronization input or configurable active high
torch enable. Has an internal pull-down resistor of 400k between TX and
ground.
C4
AGND
Analog ground.
C5
LED1
Single output 1 for backlight LED.
D1
CPGND
Inverter charge pump ground.
D2
SCL
I2C serial clock input. An external pull-up resistor is required.
D3
STRB
Active high hardware flash enable. Drive STRB high to turn on flash pulse. Has
an internal pull-down resistor of 400k between STRB and ground.
D4
PWM
PWM dimming input for backlight LED.
D5
LED2
Single output 2 for backlight LED.
E1
C2
Fly capacitor 1 negative connection of inverter charge pump. Connect a 10F
ceramic capacitor between this pin and C1.
E2, F2
FlashLED
High-side current source output for flash LED.
E3, F3
FlashOUT
Step-up flash DC-DC converter output. Connect a 10F ceramic capacitor
between this pin and Ground.
E4, F4
FlashSW
Drain connection for internal N-MOSFET and synchronous P-MOSFET
switches. Connect a 0.47 to 1H inductor between FlashSW and VIN.
E5
VIN
Input voltage connection. Connect VIN to the input supply, and bypass to
Ground with a 10F or larger ceramic capacitor.
F1
CPOUT
Charge pump negative terminal output. Connect a 10F ceramic capacitor
between this pin and ground.
F5
FlashGND
Flash boost power ground.
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RT4832A
Functional Block Diagram
VIN
UVLO
OTP
OVP
LEDOUT
Vrb
LEDSW
BL
PWM/Drv
Back Light DC to DC Core
EN
LEDGND
PWM
RC
Control Logic
OCP
Vrb
MINFB
PWM
VrF
OSC
LED2
Flash Light DC to DC Core
Current Source
LED1
SDA
fledsh
VrF
FlashLED
SCL
MINFB
ENM
LED
Short
Current Source
POR
FlashLED
OVP
ENP
APR
FlashOUT
Vin Monitor
Output
Short
Txmask
Back Gate
Control
STRB
FlashSW
FL
PWM/Drv
fledsh
VrLCM
FlashGND
OCP
POS
LCM DC to DC Core
POS
SCP
LDO
LCMOUT
AGND
C1
C2
X1 Negative Charge Pump
fledsh
LCM
PWM/Drv
Back Gate
Control
LCMSW
CPOUT
OCP
NEG
SCP
LCMGND
CPGND
Copyright © 2017 Richtek Technology Corporation. All rights reserved.
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RT4832A
Absolute Maximum Ratings
(Note 1)
Supply Voltage (VIN) --------------------------------------------------------------------------------------------------0.3V to 6V
LED Boost Output Voltage (LEDOUT) ----------------------------------------------------------------------------0.3V to 37V
LED Switching Voltage (LEDSW) ----------------------------------------------------------------------------------0.3V to 37V
LED Current Source Voltage (LED1, LED2) ---------------------------------------------------------------------0.3V to 36V
LCM Boost Output Voltage (LCMOUT, POS) -------------------------------------------------------------------0.3V to 6.3V
LCM Switching Voltage (LCMSW, C1) ----------------------------------------------------------------------------0.3V to 6.3V
Negative Charge Pump Switching Voltage (C2) ----------------------------------------------------------------0.3V to 6.5V
Negative Charge Pump Voltage (CPOUT) -----------------------------------------------------------------------0.3V to 6.5V
Flash Switching Voltage (FlashSW) -------------------------------------------------------------------------------0.3V to 6V
Flash Output Voltage (FlashOUT)----------------------------------------------------------------------------------0.3V to 6V
Flash LED Voltage (FlashLED) -------------------------------------------------------------------------------------0.3V to 6V
Digital Clock Control Pins (SDA, SCL, PWM) -------------------------------------------------------------------0.3V to 6V
Other Pins (EN, ENM, ENP, Txmask, STRB) -------------------------------------------------------------------0.3V to 6V
Power Dissipation, PD @ TA = 25C
WL-CSP-30B 2.24x2.64 (BSC) ------------------------------------------------------------------------------------ 3.15W
Package Thermal Resistance
(Note 2)
WL-CSP-30B 2.24x2.64 (BSC), JA ------------------------------------------------------------------------------ 31.7C/W
Lead Temperature (Soldering, 10 sec.) -------------------------------------------------------------------------- 260C
Junction Temperature ------------------------------------------------------------------------------------------------ 150C
Storage Temperature Range --------------------------------------------------------------------------------------- 65C to 150C
ESD Susceptibility
(Note 3)
HBM (Human Body Model) ----------------------------------------------------------------------------------------- 2kV
Recommended Operating Conditions
(Note 4)
Supply Voltage, VIN -------------------------------------------------------------------------------------------------- 2.5V to 5.5V
Ambient Temperature Range--------------------------------------------------------------------------------------- 40C to 85C
Junction Temperature Range -------------------------------------------------------------------------------------- 40C to 125C
Electrical Characteristics
(VIN = 3.6V, CVIN = 10F, TA = 25C, unless otherwise specified)
Parameter
Symbol
Test Conditions
Min
Typ
Max
Unit
2.5
--
5.5
V
Power Supply
Input Voltage Range
VIN
UVLO
UV
VIN falls
--
2.2
2.3
V
UVLO Hysteresis Voltage
UVhys
30
50
200
mV
VIN Supply Current
IQ
VIN rises after UVLO
LCD Bias enable, Back Light turned
off, EN = H, LCMOUT = 5.2V
--
0.5
--
mA
VIN Shutdown Current
ISHDN
VIN = 5V, EN = L
--
1
--
A
Thermal Shutdown
TSD
--
145
--
C
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is a registered trademark of Richtek Technology Corporation.
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RT4832A
Parameter
Thermal Shutdown Hysteresis
Symbol
Test Conditions
TSDHYS
Min
Typ
Max
Unit
--
15
--
C
Flash LED
Accuracy of Flash Output
Current 1/2
AIFL1
IFLED > 375mA
4
--
4
AIFL2
IFLED = 25mA to 375mA
10
--
10
FLED Sense Voltage 1/2
VDSFL
FlashOUT FlashLED,
IFLED = 750mA (per channel)
--
300
--
mv
Flash 1/2 Start-up Current
IFLST
FlashOUT = 3.6V, FlashLED to
Ground (per channel)
2
2.5
4
mA
Flash Pre-charge Current
IFLPRE
FlashOUT = VIN 0.15V
40
150
300
mA
Flash Switching Frequency
f FOSC
0x07[7:6] = 01
1.8
2
2.2
MHz
Safety Timeout
tOUT
0x07[4:0] = 10000, Strb goes high until
0x0B[1] = 01
460
512
563
ms
Maximum Duty Cycle
DmaxFL
0x07[6] = 01
--
70
--
%
Flash N-MOSFET Ron
RonFLN
20
65
130
m
Flash P-MOSFET Ron
RonFLP
20
80
160
m
FlashOUT = 3.6V
%
Flash N-MOSFET Current Limit IOCPFL
0x07[5] = 1
2.24
2.8
3.36
A
VIN Monitor Voltage
VIN falls until 0x0B[4] = 01,
0x08[2:0] = 100, 0x09[0] = 1
2.82
2.9
2.98
V
VIN Monitor Hysteresis Voltage VMONhys
VIN rises until 0x0B[4] = 10,
0x08[2:0] = 100, 0x09[0] = 1
1
5
--
%
Flash Output Short Voltage
VFLSH
FlashOUT < 1.5V for 1msec, 0x0B[5] =
01
0
--
1.5
V
Flash LED 1/2 Short Voltage
VFLEDSH
FlashLED < 1.5V for 1msec, 0x0B[2] =
01 (per channel)
0
--
1.5
V
Flash Over Voltage Protection
VFLOVP
FlashOUT > VIN, 0x0B[6] = 01
5
5.3
5.6
V
Accuracy of Back Light Output
Current 1/2
AIBL1
IBLED = 5mA to 25mA
3
--
3
AIBL2
IBLED = 0.5mA to 5mA
5
--
5
Matching of Output Current
MIBL
IBLED = 5mA to 25mA
3
--
3
%
BLED Sense Voltage 1/2
VDSBL
VIN = 3V, IFBx = 25mA
--
500
--
mV
Back Light Switching
Frequency
fblosc
0x03[7] = 1
0.9
1
1.1
MHz
Maximum Duty Cycle
DmaxBL
0x03[7] = 1
90
93
--
%
Back Light N-MOSFET Ron
RonBLN
100
270
400
m
Back Light Current Limit
IOCPBL
0.96
1.2
1.44
A
Back Light Over Voltage
Protection
VBLOVP
0x02[7:5] = 001
21
22
23
V
Accuracy of POS Voltage
VPOS
0x0E[5:0] = 010100, IOUT = 0mA
1
--
1
%
Accuracy of CPOUT
VCPOUT
0x0F[5:0] = 010100, IOUT = 0mA
1.5
--
1.5
%
Drop-Out Voltage
VDO
VLCMOUT = VPOS = 5.2V,
IOUT = 50mA
--
100
--
mV
VMON
Back Light LED
%
DSV
Copyright © 2017 Richtek Technology Corporation. All rights reserved.
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January 2017
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RT4832A
Parameter
Symbol
Test Conditions
Min
Typ
Max
Unit
DSV Switching Frequency
f DSV
0.9
1
1.1
MHz
Maximum Duty Cycle
DMXDSV
90
93
--
%
DSV N-MOSFET Ron
RonNDSV
0.05
0.3
0.6
DSV P-MOSFET Ron
RonPDSV
0x0F[5:0] = 010100
0.05
0.5
1
Charge Pump Equivalent
Resistance
Reqx1
VLCMOUT = 5.2V, IOUT = 50mA
--
2
--
VPOS Discharge Resistor
RDP
0x0C[4] = 1
--
70
--
VCPOUT Discharge Resistor
RDN
0x0C[3] = 1
--
20
--
LCMOUT Current Limit
IOCPLCM
0x0E[5:0] = 010100
0.88
1.1
1.32
A
POS Short Protection Voltage
VSCPP
--
0.8 x
VPOS
--
V
--
V
CPOUT Short Protection
Voltage
VSCPN
--
0.25
0.8 x
(VCP
OUT)
Logic Control (PWM, EN, ENP, ENM, SCL, SDA, TXMASK, STRB)
Input Logic Low
VIL
--
--
0.4
V
Input Logic High
VIH
1.4
--
--
V
Note 1. Stresses beyond those listed “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 may affect
device reliability.
Note 2. JA is measured under natural convection (still air) at TA = 25°C with the component mounted on a high
effective-thermal-conductivity four-layer test board on a JEDEC 51-7 thermal measurement standard.
Note 3. Devices are ESD sensitive. Handling precaution recommended.
Note 4. The device is not guaranteed to function outside its operating conditions.
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RT4832A
VLCM
(2V/Div)
VLCM
VPOS
VPOS
(2V/Div)
VCPOUT
(2V/Div)
IIN
(500mA/Div)
VCPOUT
IIN
Time (1ms/Div)
DSV Power off with Discharge
VLCM
(2V/Div)
VLCM
VPOS
VPOS
(2V/Div)
VCPOUT
(2V/Div)
VCPOUT
IIN
IIN
(500mA/Div)
Time (1ms/Div)
DSV Ripple 0mA
VCPOUT
(20mV/Div)
offset (-5V)
IIN
(50mA/Div)
VIN = 3.7V, VLCM = 5.2V, VPOS = 5V,
VCPOUT = -5V, IPOS_CPOUT = 0mA
VIN = 3.7V, VLCM = 5.2V, VPOS = 5V,
VCPOUT = -5V, IPOS_CPOUT = 0 to
5o to 0mA
DSV Load Transient
VPOS
(20mV/Div)
offset(5V)
VPOS
(20mV/Div)
offset(5V)
VCPOUT
(20mV/Div)
offset (-5V)
Time (10ms/Div)
Time (2ms/Div)
DSV Accuracy_POS
DSV Ripple 50mA
Time (500s/Div)
Copyright © 2017 Richtek Technology Corporation. All rights reserved.
January 2017
VIN = 3.7V, 0x0C = 0x48, 0x0D = 0x18,
0x0E = 0x14, 0x0F = 0x14
0.8
0.6
Accuracy (%)
VCPOUT
(20mV/Div)
offset (-5V)
DS4832A-00
1.0
VIN = 3.7V, VLCM = 5.2V, VPOS = 5V,
VCPOUT = -5V, IPOS_CPOUT = 50mA
VPOS
(20mV/Div)
offset(5V)
VIN = 3.7V, VLCM = 5.2V, VPOS = 5V, VCPOUT
=- 5V, IPOS_CPOUT = 0mA, DSV_VPOS_disc
enable, DSV_CPOUT_disc enable.
DSV Power On
VIN = 3.7V, VLCM = 5.2V, VPOS = 5V, VCPOUT =
-5V, IPOS_CPOUT = 0mA, delay time = No
constraint, POS slew rate=2.8mV/us, CPOUT slew
rate = 2.9mV/us
Typical Operating Characteristics
0.4
0.2
0.0
-0.2
2.5V
3V
3.5V
4V
4.5V
-0.4
-0.6
-0.8
-1.0
0
10
20
30
40
DAC Code
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RT4832A
BLED Accuracy Linearty
DSV Accuracy_CPOUT
2
1.0
1
VIN = 3.7V, 0x0C = 0x48, 0x0D = 0x18,
0x0E = 0x14, 0x0F = 0x14
0.8
0
Accuracy (%)
Accuracy (%)
0.6
0.4
0.2
0.0
-0.2
2.5V
3V
3.5V
4V
4.5V
-0.4
-0.6
-0.8
-1
-2
-3
-4
-5
-6
VIN = 3.7V, 2P10S, LED Brightness
code from 0 to 2048
-7
-8
0.005
-1.0
0
10
20
30
40
0.01
0.015
DAC Code
BLED Matching Linearty
0.025
BLED ILED vs. Brightness Code
2.0
0.025
VIN = 3.7V, 2P10S, LED Brightness
code from 0 to 2048
1.8
1.6
0.020
1.4
1.2
I LED (A)
Matching (%)
0.02
I LED (A)
1.0
0.8
0.015
0.010
0.6
0.4
0.005
VIN = 3.7V, 2P10S, LED Brightness
code from 0 to 2048, 0x02[4] = 1
0.2
0.0
0.005
0.000
0.01
0.015
0.02
0.025
0
256
768
1024 1280 1536 1792 2048
BLED Efficiency vs. Input Voltage
BLED ILED vs. Brightness Code
90
0.025
VIN = 3.7V, 2P10S, LED Brightness
code from 0 to 2048, 0x02[4] = 0
88
86
Efficiency (%)
0.020
I LED (A)
512
Brightness Code
I LED (A)
0.015
0.010
1MHz
500kHz
84
82
80
78
76
74
0.005
VIN = 2.5V to 5.5V, 2P10S,
72
ILED = 25mA per string
70
0.000
0
256
512
768
1024 1280 1536 1792 2048
Brightness Code
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10
2.5
3
3.5
4
4.5
5
5.5
Input Voltage (V)
is a registered trademark of Richtek Technology Corporation.
DS4832A-00
January 2017
RT4832A
VIN = 3.7V to 4.5V
VIN
(1V/Div)
VIN = 3.7V, IFLED_flash = 1.5A,
IFLED_strobe = 375mA, Strobe timeout
=1 024ms, 0x09 = 0x1C, 0x0A
Txmask
BLED Line Transient
STRB
(5V/Div)
TXMASK
(5V/Div)
ILED
(20mA/Div)
CS2
(1V/Div)
IFLED
(500mA/Div)
CS1
(1V/Div)
Time (1ms/Div)
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Time (200ms/Div)
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RT4832A
Register Map
RT4832A IC slave address = 7’b 0010001. I2C interface supports fast mode (bit rate up to 400kb/s).
Address
Address Name
BIT
R/W
Default
(Reset Value)
0x01
Vendor Code
1:0
R
10
10 RICHTEK
BLED OVP
7:5
R/W
001
[000] = 18V, [001] = 22V, [010] = 25V, [011] = 29V,
[100] = 33V, [101 to 111] = 36V
BLED
Mapping Code
4
R/W
1
[0] = Exponential, [1] = Linear.
BLED
PWM Config.
3
R/W
0
[0] = Active High, [1] = Active Low.
Reserved
2:0
R/W
000
BL SW Frequency
7
R/W
0
0x02
BL Ramp Rate
6:3
R/W
0011
Reserved
2:1
R/W
00
0x03
[0] = 500kHz, [1] = 1MHz
[0000] = 0s, [0001] = 500s, [0010] = 750s,
[0011] = 1ms, [0100] = 2ms, [0101] = 5ms, [0110] =
10ms, [0111] = 20ms, [1000] = 50ms, [1001] =
100ms, [1010] = 250ms, [1011] = 800ms, [1100] =
1s, [1101] = 2s, [1110] = 4s, [1111] = 8s
11th bit enable of bled brightness control
[0] = 10 bit brightness control, reg0x40[1] is MSB,
reg0x04[2] is ignore.
[1] = 11 bit brightness control, reg0x40[2] is MSB.
Bled11th
0
R/W
1
Reserved
7:3
R/W
00000
11th LSB
2
R/W
1
BLED Brightness
MSB
1:0
R/W
11
1024 steps, MSB
BLED Brightness
LSB
7:0
R/W
11111111
1024 steps, LSB
0x04
0x05
Description
FLED LED1/2 Torch
Current
7:4
R/W
0011
FLED LED1/2 Strobe
3:0
Current
R/W
1110
0x06
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[0000] = 25mA, [0001] = 50mA, [0010] = 75mA,
[0011] = 100mA, [0100] = 125mA, [0101] = 150mA,
[0110] = 175mA, [0111] = 200mA, [1000] = 225mA,
[1001] = 250mA, [1010] = 275mA, [1011] = 300mA,
[1100] = 325mA, [1101] = 350mA, [1110 to 1111] =
375mA
[0000] = 100mA, [0001] = 200mA, [0010] = 300mA,
[0011] = 400mA, [0100] = 500mA, [0101] = 600mA,
[0110] = 700mA, [0111] = 800mA, [1000] = 900mA,
[1001] = 1000mA, [1010] = 1100mA, [1011] =
1200mA, [1100] = 1300mA, [1101] = 1400mA,
[1110 to 1111] = 1500mA
is a registered trademark of Richtek Technology Corporation.
DS4832A-00
January 2017
RT4832A
Address Name
BIT
R/W
Default
(Reset Value)
FLED SW Freq.
FL Current Limit
7:6
5
R/W
R/W
00
1
FL Strobe Timeout
4:0
R/W
01111
dsv_periodic_mode
7
R/W
0
dsv_freq_pm
6
R/W
0
dsv_en_mode
5
R/W
0
Reserved
4
R/W
0
fla_ovp_sden
3
R/W
1
FLED VIN Monitor
2:0
R/W
100
Rst_sw_all
7
WC
0
[0] = turn on DSV only if EN = 1, [1] = turn on DSV
only if (EN+ENP+ENM) = 1
-Flash OVP shutdown enable [0]=Report only, [1] =
OVP Shutdown
[000] = 2.5V, [001] = 2.6V, [010] = 2.7V, [011] =
2.8V, [100] = 2.9V, [101] = 3V, [110] = 3.1V, [111] =
3.2V
Software reset [0] = Disable, [1] = Reset
PWM Enable
6
R/W
0
[0] = PWM Ignored, [1] = PWM Enable
dsv_ext_en
5
R/W
0
DSV external control enable [0] I2C control, [1]
external pin control
Strobe Enable
4
R/W
0
[0] = I2C Flash, [1] = Strobe Flash
Tx Polarity
3
R/W
1
[0] = Active Low, [1] = Active High
Tx Enable
2
R/W
0
[0] = Tx Ignored, [1] = Tx Enabled
VIN Monitor Mode
1
R/W
1
[0] = Torch, [1] = Standby
VIN Monitor En
0
R/W
0
[0] = Disable, [1] = VIN Monitor Enabled
Rst_sw
7
WC
0
Fla_ch2_enb
6
R/W
0
BL OVP Disable
5
R/W
0
[0] = Report only, [1] = OVP Shutdown
BLED1 En
4
R/W
0
[0] = Disable, [1] = Enable
BLED2 En
3
R/W
0
[0] = Disable, [1] = Enable
Torch/Flash
2
R/W
0
[0] = Torch, [1] = Flash
Flash Enable
Back Light Enable
1
0
R/W
R/W
0
0
[0] = Off, [1] = Enable Flash
[0] = Off, [1] = Enable Back Light
Back Light OVP
7
R
0
[0] = Normal, [1] = Fault
Flash OVP
6
R
0
[0] = Normal, [1] = Fault
Flash Output Short
5
R
0
[0] = Normal, [1] = Fault
VIN Monitor
Tx Interrupt
4
3
R
R
0
0
[0] = Normal, [1] = VIN Monitor Threshold Crossed
[0] = Normal, [1] = Tx Event Occurs
FLED1/2 Short
2
R
0
[0] = Normal, [1] = Fault
Flash Timeout
Thermal Shutdown
1
0
R
R
0
0
[0] = Normal, [1] = Time out
[0] = Normal, [1] = Fault
Address
0x07
0x08
0x09
0x0A
0x0B
Copyright © 2017 Richtek Technology Corporation. All rights reserved.
DS4832A-00
January 2017
Description
[00] = 4MHz, [01] = 2MHz
[0] = 1.9A, [1] = 2.8A
[00000] = 32ms
…..
[01111] = 512ms
[11111] = 1024ms, each step = 32ms
DSV periodic mode [0] = always on if DSV is
enable, [1] = DSV periodic mode
[0] = 20Hz, [1] = 33Hz
Software reset [0] = Disable, [1] = Reset excluding
DSV
[0] = FLASH channel2 enable, [1] = FLASH
channel2 disable
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RT4832A
Address
0x0C
Address Name
BIT
R/W
Default
(Reset Value)
pwr_sav
7
R/W
0
Power saving mode, [0] = Disable, [1] = Enable
DSV_VPOS_en
6
R/W
0
DSV VPOS enable, [0] = Disable, [1] = Enable
DSV_VPOS_gnd
5
R/W
1
DSV VPOS Ground, [0] = Floating,
[1] = Grounding only function when VPOS is
disable
DSV_VPOS_disc
4
R/W
0
DSV VPOS discharge 20ms when shutdown,
[0] = Disable, [1] = Enable
DSV_VCPOUT_en
3
R/W
0
DSV_ VCPOUT _gnd
2
R/W
1
DSV_ VCPOUT _disc
1
R/W
0
DSV_Startup
0
R/W
0
DSV startup mode
[0] = closed loop, waiting 80%
[1] = open loop, go after soft-start dimming
00
DSV delay time between VPOS and VCPOUT
[00] = No constraint
[01] = 1ms
[10] = 2ms
[11] = 5ms
DSV_delay
7:6
R/W
0x0D
Vboost Voltage
DSV_VPOS_slew
5:0
7:6
R/W
R/W
101000
01
0x0E
VPOS Voltage
5:0
DSV_VCPOUT_slew 7:6
R/W
R/W
011110
5:0
R/W
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DSV VCPOUT enable, [0] = Disable, [1] = Enable
DSV VCPOUT Ground, [0] = Floating,
[1] = Grounding only function when VCPOUT is
disable
DSV VCPOUT discharge 20ms when shutdown,
[0] = Disable, [1] = Enable
[000000] = 4V
…..
[010100] = 5V
……
[101011] = 6.15V (0.05V per step)
VPOS rising slew rate control
[00] = 8.5mV/s
[01] = 5.6mV/s,
[10] = 4.6mV/s
[11] = 2.8mV/s
[000000] = 4V
…..
[011110] = 5.5V
……
[101000] = 6V (0.05V per step)
10
VCPOUT falling slew rate control
[00] = 9.9mV/s
[01] = 6.2mV/s,
[10] = 4.9mV/s
[11] = 2.9mV/s
011100
[000000] = 4V
…..
[011100] = 5.4V
……
[101000] = 6V (0.05V per step)
0x0F
VCPOUT Voltage
Description
is a registered trademark of Richtek Technology Corporation.
DS4832A-00
January 2017
RT4832A
Address
0x10
Address Name
BIT
R/W
Default
(Reset Value)
Reserved
7
R
0
[0] = Normal, [1] = Fault
VPOS_SCP
6
R
0
[0] = Normal, [1] = Fault
VCPOUT_SCP
5
R
0
[0] = Normal, [1] = Fault
LCMOUT OCP
4
R
0
[0] = Normal, [1] = Fault
VPOS OCP
3
R
0
[0] = Normal, [1] = Fault
VCPOUT OCP
2
R
0
[0] = Normal, [1] = Fault
Flash OCP
1
R
0
[0] = Normal, [1] = Fault
Back Light OCP
0
R
0
[0] = Normal, [1] = Fault
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Description
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RT4832A
Application Information
I2C
I2C Write Control
Slave ID
S
0
0
1
0
0
R/W
0
1
0
A
A
Data Address
P
ACK from Slave
ACK from Slave
P
I2C
0
Read Control
0
1
0
Slave ID
R/W
0
0
A
Write Data2
P
ACK from Slave
Slave ID
S
A
Write Data1
ACK from Slave
1
0
A
A
Data Address
ACK from Slave
0
0
1
0
ACK from Slave
A
Read Data1
ACK from Master
R/W
0
0
1
1
A
ACK from Slave
A
Read Data2
P
NACK from Master
|VCPOUT| should be higher than 150mV for good
performance but the headroom voltage between
DSV
The RT4832A provides programmable LCMOUT, POS,
CPOUT value. Table 1 contains the detail for DSV
operation setting. The LCMOUT should be selected to
provide enough headroom for good ripple and load
transient performance. The headroom voltage between
LCMOUT and the maximum value of VPOS and
LCMOUT and |VCPOUT| should not be higher than
200mV to avoid the larger ripple at VCPOUT.
The OCP level of POS is 250mA and CPOUT is 150mA
typically.
Table 1. DSV Operation Setting
Channel
Range
Step
Register
Default Value
Suggest Setting
LCMOUT
4V to 6.15V
50mV/LSB
0x0D[5:0]
6V
5.7V
VPOS
4V to 6V
50mV/LSB
0x0E[5:0]
5.5V
5.5V
CPOUT
4V to 6V
50mV/LSB
0x0F[5:0]
5.4V
5.5V
The DSV con be controlled either by pins or register bits. Table 2 is the DSV operation control table.
Table 2. DSV Operation Control Table
Dsv_ext_en DSV_vpos_en DSV_vneg_en
ENM pin
0x09[5]
0x0C[6]
0x0C[3]
X
X
X
X
EN pin
ENP pin
0
X
1
X
X
0
0
0
Standby
1
0
0
1
X
X
Standby
1
X
X
0
1
0
VPOS enable
1
X
X
0
0
1
VNEG enable
1
X
X
0
1
1
VPOS & VNEG enable
1
1
0
1
X
X
VPOS enable
1
1
0
1
1
1
1
1
X
X
X
X
VNEG enable
VPOS & VNEG enable
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Status
Shutdown
is a registered trademark of Richtek Technology Corporation.
DS4832A-00
January 2017
RT4832A
Discharge and Short to GND Function
The RT4832A provides internal switch resister to
discharge voltage of VPOS and CPOUT during the
channel power off. Set the 0x0C[4] = 1 for VPOS
discharge enable and 0x0C [1]=1 for CPOUT discharge
enable. When the voltage discharge to GND, set the
0x0C[5] = 1 and 0x0C[2] = 1 will keep the output
connect to GND.
Power Saving Mode
The RT4832A provides the power saving mode to
bypass the input voltage to VPOS. Enable the 0x0C[7]
= 1 to control the high side switch of boost converter
and the LDO fully turn on to save the quiescent current
and switching current. The POS is equal to Vin and
CPOUT is equal to –Vin when power saving mode.
Delay Time Control of POS & CPOUT
The RT4832A provides the delay time control between
POS and CPOUT power on and off. The bits of the
0x0D[7:6] is used to set the delay time. Table 3 and
Figure 2 shows the delay time and the sequence for
DSV power on and off.
Table 3. DSV Delay Time Control Table
0x0D[7:
6]
Delay time
Power on
00
No
constraint
POS start ramp up when ENP = H or
dsv_vpos_en = 1,
CPOUT start ramp down when ENM
= H or dsv_vcpout_en = 1.
CPOUT start discharge when ENM = L or
dsv_vcpout_en = 0,
POS start discharge when ENP = L or
dsv_vpos_en = 0.
1ms
POS start ramp up when ENP = H or
dsv_vpos_en = 1
CPOUT start ramp down after POS
ramp up to target and delay 1ms even
the ENM = H or dsv_vcpout_en = 1
CPOUT start discharge when ENM = L or
dsv_vcpout_en = 0
POS start discharge after CPOUT discharge to
GND and delay 1ms even the ENP = L or
dsv_vpos_en = 0
2ms
POS start ramp up when ENP = H or
dsv_vpos_en = 1
CPOUT start ramp down after POS
ramp up to target and delay 2ms even
the ENM = H or dsv_vcpout_en = 1
CPOUT start discharge to GND when ENM = L
or dsv_vcpout_en = 0
POS start discharge after CPOUT discharge to
GND and delay 2ms even the ENP = L or
dsv_vpos_en = 0
5ms
POS start ramp up when ENP = H or
dsv_vpos_en = 1
CPOUT start ramp down after POS
ramp up to target and delay 5ms even
the ENM = H or dsv_vcpout_en = 1
CPOUT start discharge when ENM = L or
dsv_vcpout_en = 0
POS start discharge after CPOUT discharge to
GND and delay 5ms even the ENP = L or
dsv_vpos_en = 0
01
10
11
Periodic Mode
The RT4832A supports the DSV periodic mode with
the enable bit 0x08[7] and frequency select bit 0x08[6].
dsv_periodic_mode
0x08[7]
0
0
1
1
January 2017
In the periodic mode, the enable channel of the POS
and CPOUT repeat on/off. The delay time, slew rate,
discharge and GND connect follow the register setting.
Table 4. Periodic Mode Control Table
dsv_freq_pm
ton (ms)
0x08[6]
0
X
1
X
0
2
1
1.6
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DS4832A-00
Power off
tperiod (ms)
X
X
50
30
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RT4832A
VIN
Periodic
mode
ENP
VBST
VPOS
ENM
VCPOUT
0
0
tperiod
tperiod
0
ton
0
ton
ton
...
0
0
0
...
Figure 3. Periodic Mode Control
Backlight LED
The RT4832A provides brightness controllable
backlight LED for maximum 2P10S application. The
LED current be set via register and external PWM pin.
Each channel can be control by enable bits (LED1 in
register 0x0A [4] and LED2 in register 0x0A [3]). The
ramp time from one brightness current to another
current can be adjusted from 0ms to 8000ms in the
register 0x03[6:3]. There are two different ways to map
Back Light
Enable
0x0A[0]
BLED1 En
0x0A[4]
the brightness code (or PWM duty cycle) to the LED
current: linear and exponential mapping.
The RT4832A LED serial number depends on the
minimum voltage of the battery and the forward
voltage(VF) of the LED. If the minimum voltage is 2.7V
and the VF of the backlight LED is 3.2V, the maximum
number of each string is 8.
Table 5. BLED Operation Control Table
PWM
BLED2 En
Enable
PWM pin
0x0A[3]
0x09[6]
Status
0
X
X
X
X
Standby
1
0
0
X
X
LED Bias enable
1
1
0
0
X
ILED1 = BLED Brightness
1
0
1
0
X
ILED2 = BLED Brightness
1
1
1
0
X
ILED1 & ILED2 = BLED Brightness
1
1
0
1
Duty
ILED1 =(BLED Brightness*PWM Duty)
1
0
1
1
Duty
ILED1 =(BLED Brightness*PWM Duty)
1
1
1
1
Duty
ILED1 = ILD2 = (BLED Brightness*PWM
Duty)
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is a registered trademark of Richtek Technology Corporation.
DS4832A-00
January 2017
RT4832A
Brightness Control
ILED = 0.0122mA*Brightness Code
a. PWM Brightness Dimming
In exponential mapped mode the LED current follows
the relationship:
Besides programmable built-in I2C backlight LED
current control, the RT4832A features a built-in PWM
dimming current control by setting register 0x09[6]=1,
offering a linear current dimming by external clock
source. In order to guarantee the PWM dimming
resolution (7 bit at > 15kHz application), recommending
dimming frequency have to be operated at range of
400Hz to 20kHz.
2
b. I C Brightness Dimming
The RT4832A is built-in an I2C 10-bit or 11-bit
resolution brightness control with maximum 25mA per
string.
When LED brightness is controlled from the I2C
brightness registers (register 0x09[6]=0) , the 11-bit
brightness data is default to controls the LED current in
LED1 and LED2.
The I2C brightness dimming is the concatenation of the
two brightness registers (registers 0x04[2:0] and
0x05[7:0]). The LED current only changes when the
MSBs are written, meaning that to do a full 11-bit
current change via I2C, first the 3 MSBs are written and
then the 8 LSBs are written. It can be selected as either
linear or exponential. (register 0x02[4]).
In linear mapped mode the LED current follows the
ILED = 0.0183mA*(1.0035Brightness Code )
The 11-bit exponential mapping is small enough such
that the transition from one code to the next in terms of
LED brightness is not distinguishable to the eye.
c. LED Brightness Current and PWM
The LED brightness current is controlled with the
register and the PWM Duty Cycle. LED current
mapping can be selected as either linear or exponential,
shows as the Figure 4. The LED current is
approximated by the equation :
With linear mapping the 10 bit code to current is
approximates by the equation :
ILED = 0.0244mA*Brightness Code*PWM Duty
With linear mapping the 11 bit code to current is
approximates by the equation :
ILED = 0.0122mA*Brightness Code*PWM Duty
With exponential mapping the 10 bit code to current is
approximates by the equation :
ILED = 0.0183mA*(1.0071Brightness Code*PWM Duty )
With exponential mapping the 11 bit code to current is
approximates by the equation :
ILED = 0.0183mA*(1.0035Brightness Code*PWM Duty )
relationship :
10 bit LED Current vs. Exponential
Brightness Code
0.025
0.025
0.020
0.020
LED Current (mA)
LED Current (mA)
10 bit LED Current vs. Linearty
Brightness Code
0.015
0.010
0.015
0.010
0.005
0.005
0.000
0.000
0
256
512
768
Brightness Code (LSB)
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DS4832A-00
January 2017
1024
0
256
512
768
1024
Brightness Code (LSB)
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RT4832A
11 bit LED Current vs. Exponential
Brightness Code
0.025
0.025
0.020
0.020
LED Current (mA)
LED Current (mA)
11 bit LED Current vs. Linearty
Brightness Code
0.015
0.010
0.015
0.010
0.005
0.005
0.000
0.000
0
256
512
768
1024 1280 1536 1792 2048
0
256
Brightness Code (LSB)
512
768
1024 1280 1536 1792 2048
Brightness Code (LSB)
Figure 4. LED Current vs Brightness Code
Ramp Rate
There are 16 programmable ramp rates available in the
RT4832A. These ramp rates are programmable as a
time. Therefore, the ramp time from one current
set-point to the next, depends on the register 0x03[6:3].
Over-Voltage Protection (Open LED, Open Circuit)
The RT4832A provides an internal over voltage
protection to limit its output voltage. The OVP function
prevents the RT4832A from damaging while open LED
or open circuit condition occurs. Once the open circuit
condition is removed, and the RT4832A will return to
normal operation.
Over-Current Protection
The RT4832A features a 1.2A OCP. The driver
provides cycle-by-cycle current limit function to control
the current on power switch. The boost switch turns off
when the inductor current reaches this current
threshold and it remains off until the beginning of the
next switching cycle. This protects the RT4832A and
external component under overload conditions.
Flash LED
The RT4832A FLED provides a current regulated
output to drive high current white LEDs for camera
flash applications. The output current provides up to
375mA for torch and 1.5A for strobe per channel white
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LEDs for camera flash applications. It adopts two
channels to provide accurately regulated current flow
through two separate white LEDs.
The RT4832A FLED can be set in Flash or Torch mode
by the register and the STRB pin. Figure 5 shows the
RT4832A FLED operation and Table 6 contains the
FLED operation control table.
Flash Mode
In Flash Mode, FLED provides 15 different current
levels from 100mA to 1500mA in step of 100mA. The
flash currents are adjusted via the register 0x06[3:0] for
flash brightness. RT4832A provides 32 steps timeout
from 32ms to 1024ms in step of 32ms for flash mode
only. The Flash mode can be set via the register
0x0A[1] = 1 and 0x0A[2] = 1.
Timeout
To avoid the thermal increase from flash current,
RT4832A provides 32 steps timeout from 32ms to
1024ms in step of 32ms for flash mode only. The
timeout can be set via the register 0x07[4:0]. Once a
flash event is completed, the Flash Timeout flag in
register 0x0B bit [1] is set. This is a status only flag so
the Flash Enable bit is not cleared. If a Flash event is
activated via the STROBE pin and STROBE transitions
low after the end of the programmed flash timeout, the
Flash event is terminated at the programmed Flash
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DS4832A-00
January 2017
RT4832A
Timeout and the Flash time out flag is set.
VIN Monitor
In Flash mode, to avoid the flash current to let VIN drop
to UVLO, RT4832A provides VIN monitor function for
the battery voltage detecting. If the battery voltage less
than the VIN monitor value, FLED will be into Torch
mode and output the torch current. This function can be
enable via set register 0x09[0] = 1 and 0x08[2:0] is the
Vin monitor value. The Register 0x0B [4] has the fault
flag set when the input voltage crosses the VIN value.
0x08[2:0]
000
001
010
011
100
101
110
111
FLED VIN Monitor Level
2.5V
2.6V
2.7V
2.8V
2.9V (default)
3V
3.1V
3.2V
Torch Mode
The torch mode can be set via the register 0x0A[1] = 1
and 0x0A[2] = 0.
Table 6. FLED Operation Control Table
Flash
Strobe
Torch/
STRB
Enable Enable
Flash Status
pin
0x0A[1] 0x09[4]
0x0A[2]
0
X
X
X
Standby
1
1
0
X
Standby
1
1
1
0
1
1
Rising
edge
1
1
0
X
0
1
Falling
edge
X
1
Torch
mode
Flash
mode
Torch
mode
Flash
mode
Txmask
The TXmask pin is designed to clamp the flash LED to
torch current or no current that depend on the register
setting when the PA transmit. This function can be
enable by set the reg 0x09[2] = 1 and the reg 0x09[3] is
used to define this pin active high or low.
In Torch Mode, FLED provides 15 different current
levels from 25mA to 375mA in step of 25mA. Torch
current is activated by setting register 0x06 [7:4]. Once
Torch Mode is enabled, the current sources will ramp
up to the programmed torch current level by stepping.
Copyright © 2017 Richtek Technology Corporation. All rights reserved.
DS4832A-00
January 2017
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
21
RT4832A
Torch Mode
Strobe
Enable
0
Vin
Monitor
0
Torch/
Flash
0
STRB
0
Txmask
0
IFLED
0
Torch Current
Torch Current
Torch Current
Torch Current
Torch Current
Flash Mode
Strobe
Enable
0
Vin
Monitor
0
Torch/
Flash
0
STRB
> Flash Timeout
0
Txmask
0
Flash Current
Flash Current
Flash Current
IFLED
Flash Current
Flash Timeout
0
Torch Current
Torch Current
Torch Current
Figure 5. Flash LED Operation
Over-Voltage Protection (Open LED, Open Circuit)
The RT4832A FLED provides an internal over voltage
protection to limit its output voltage. The OVP function
prevents the RT4832A from damaging while open LED
or open circuit condition occurs. Once the open circuit
condition is removed, and the RT4832A will return to
normal operation.
of the switching cycle. Switching resumes at the start of
the next switching period. If the overcurrent condition
persists, the device operates continuously in current
limit. This prevents damage to the RT4832A and
excessive current draw from the battery during output
short-circuit conditions. When Flash occurs the current
Limit event, the FLASH_OCP flag (register 0x10 bit [1])
is set.
Over-Current Protection
Over-Temperature Protection
The RT4832A features two selectable flash inductor
current limits that are programmable through the I2C
compatible interface. When the inductor current limit is
reached, the RT4832A terminates the charging phase
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22
The RT4832A provides an over-temperature protection
to prevent the IC from overheating. When the junction
temperature rises above 145C, the OTP function will
is a registered trademark of Richtek Technology Corporation.
DS4832A-00
January 2017
RT4832A
protection threshold by 25C, the IC will enter normal
operation again.
Thermal Considerations
The junction temperature should never exceed the
absolute maximum junction temperature TJ(MAX), listed
under Absolute Maximum Ratings, to avoid permanent
damage to the device. The maximum allowable power
dissipation depends on the thermal resistance of the IC
package, the PCB layout, the rate of surrounding
airflow, and the difference between the junction and
ambient temperatures. The maximum power
dissipation can be calculated using the following
formula :
PD(MAX) = (TJ(MAX) - TA) / JA
where TJ(MAX) is the maximum junction temperature,
TA is the ambient temperature, and JA is the
junction-to-ambient thermal resistance.
For continuous operation, the maximum operating
junction temperature indicated under Recommended
Operating Conditions is 125°C. The junction-to-ambient
thermal resistance, JA, is highly package dependent.
For a WL-CSP-30B 2.24x2.64 (BSC) package, the
thermal resistance, JA, is 31.7°C/W on a standard
JEDEC 51-7 high effective-thermal-conductivity
four-layer test board. The maximum power dissipation
at TA = 25°C can be calculated as below :
4.0
Maximum Power Dissipation (W)1
be triggered and then the LED driver will be shut down.
The OTP hysteresis is 15C. Once the junction
temperature reduces below the over temperature
The maximum power dissipation depends on the
operating ambient temperature for the fixed TJ(MAX)
and the thermal resistance, JA. The derating curves in
3.2
2.8
2.4
2.0
1.6
1.2
0.8
0.4
0.0
0
25
50
75
100
125
Ambient Temperature (°C)
Figure 6. Derating Curve of Maximum Power
Dissipation
Layout Considerations
For high frequency switching power supplies, the PCB
layout is important to get good regulation, high
efficiency and stability. The following descriptions are
the guidelines for better PCB layout.
For good regulation, place the power components
as close to chip as possible. The traces should be
wide
and
short
enough
especially for the
high-current loop.
Minimize the size of the LX node and route on the
top layer only.
Place the capacitor CIN as close to VIN pin as
possible.
PD(MAX) = (125°C - 25°C) / (31.7°C/W) = 3.15W for a
WL-CSP-30B 2.24x2.64 (BSC) package.
Four-Layer PCB
3.6
Place the CPOS, CCPOUT capacitor as close to
the output pins as possible. Also place the charge
pump flying capacitor close to the RT4832A.
Figure 6 allows the designer to see the effect of rising
ambient temperature on the maximum power
dissipation.
Place the capacitor CFLED as close to FLEDOUT
pin as possible. Connect the Flash LED cathode
directly to the FLEDGND pin of the RT4832A.
Route the LED return with a dedicated path and
keep the LED1 and LED2 path short and close to
RT4832A for the good LED current performance.
Copyright © 2017 Richtek Technology Corporation. All rights reserved.
DS4832A-00
January 2017
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
23
RT4832A
CIN
■ TOP Layer
■ Bottom Layer VIN
■ Bottom Layer GND
VIN
LLCM
LBLED
CLCM
DBLED
CFLY
LCM
OUT
LCM
SW
LED
GND
LED
SW
ENM
ENP
EN
LCM
GND
LED
OUT
C1
SDA
Tx
mask
AGND
LED1
LED2
CP
GND
SCL
STRB
PWM
C2
Flash
LED
Flash
OUT
Flash
SW
VIN
CP
OUT
Flash
LED
Flash
OUT
Flash
SW
Flash
GND
CBLED
CPOS
POS
LED1
LED
OUT
CCPOUT
LED2
FLED
GND
FLED
OUT
CFLED
LFLED
CIN2
VIN
Figure 7. PCB Layout Guide
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24
is a registered trademark of Richtek Technology Corporation.
DS4832A-00
January 2017
RT4832A
Outline Dimension
Dimensions In Millimeters
Symbol
Dimensions In Inches
Min
Max
Min
Max
A
0.500
0.600
0.020
0.024
A1
0.170
0.230
0.007
0.009
b
0.240
0.300
0.009
0.012
D
2.590
2.690
0.102
0.106
D1
E
2.000
2.190
0.079
2.290
0.086
0.090
E1
1.600
0.063
e
0.400
0.016
30B WL-CSP 2.24x2.64 Package (BSC)
Copyright © 2017 Richtek Technology Corporation. All rights reserved.
DS4832A-00
January 2017
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
25
RT4832A
Footprint Information
Package
Number of
Pin
Type
Footprint Dimension (mm)
e
NSMD
WL-CSP2.24*2.64-30(BSC)
30
SMD
0.400
A
B
0.240
0.340
0.270
0.240
Tolerance
±0.025
Richtek Technology Corporation
14F, No. 8, Tai Yuen 1st Street, Chupei City
Hsinchu, Taiwan, R.O.C.
Tel: (8863)5526789
Richtek products are sold by description only. Richtek reserves the right to change the circuitry and/or specifications without notice at any time. Customers should
obtain the latest relevant information and data sheets before placing orders and should verify that such information is current and complete. Richtek cannot assume
responsibility for use of any circuitry other than circuitry entirely embodied in a Richtek product. Information furnished by Richtek is believed to be accurate and
reliable. However, no responsibility is assumed by Richtek or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may
result from its use. No license is granted by implication or otherwise under any patent or patent rights of Richtek or its subsidiaries.
Copyright © 2017 Richtek Technology Corporation. All rights reserved.
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26
is a registered trademark of Richtek Technology Corporation.
DS4832A-00
January 2017
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