RT4801T
Dual Output LCD Bias for Smartphones and Tablets
General Description
Features
The RT4801T is a highly integrated Boost and LDO
2.5V to 5.5V Supply Voltage Range
and inverting charge pump to generate positive and
Up to 90% Efficiency with Small Magnetics
negative output voltage. The output voltages can be
Support Up to 150mA Output Current
adjusted from 4V to 6V with 100mV steps by I2C
Low 1A Shut Down Current
interface protocols. With its input voltage range of 2.5V
Internal Soft-start Function
to 5.5V, the RT4801T is optimized for products
Short Circuit Protection Function
powered by single-cell batteries and symmetrical
Over-Voltage Protection Function
output currents up to 150mA. The RT4801T is available
Over-Current Protection Function
in the WL-CSP-15B 1.31x2.07 (BSC) package.
Over-Temperature Protection Function
Elastic Positive and Negative Voltage On/Off
Ordering Information
Control by ENP/ENN
RT4801T
Package Type
WSC : WL-CSP-15B 1.31x2.07 (BSC)
Voltage Output from 4V to 6V per 0.1V
Low Input Noise and EMI
Output with Programmable Fast Discharge when
IC Shut Down
Note :
Richtek products are :
Interface
RoHS compliant and compatible with the current
requirements of IPC/JEDEC J-STD-020.
Adjustable Output Voltage by I 2C Compatible
Available in the 15-Ball WL-CSP Package
Applications
Suitable for use in SnPb or Pb-free soldering processes.
TFT-LCD Smartphones
TFT-LCD Tablets
General Dual Power Supply Applications
Simplified Application Circuit
L1
VIN
VIN
RT4801T
CIN
LXP
VOP
COP
ENP
VON
CON
ENN
SCL
BST
SDA
CF1
VOP
VON
CBST
CF1
PGND
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DS4801T-01
January 2022
GND
CF2
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1
RT4801T
Pin Configuration
Marking Information
7U : Product Code
W : Date Code
(TOP VIEW)
7UW
ENN
A1
ENP
B1
A2
A3
CF2
B3
PGND
C3
CF1
D3
BST
E3
VOP
VON
B2
SCL
VIN
C1
C2
SDA
LXP
D1
D2
GND
PGND
E1
E2
BST
WL-CSP-15B 1.31x2.07 (BSC)
Functional Pin Description
Pin No.
Pin Name
Pin Function
A1
ENN
Enable control input for VON.
A2
VON
Negative terminal output.
A3
CF2
Negative charge pump flying capacitor pin.
B1
ENP
Enable control input for VOP.
B2
SCL
Clock of I2C.
PGND
Power ground.
C1
VIN
Power input.
C2
SDA
Data of I2C.
C3
CF1
Negative charge pump flying capacitor pin.
D1
LXP
Switching node of boost converter.
D2
GND
Ground. The exposed pad must be soldered to a large PCB and connected to
GND for maximum power dissipation.
D3, E2
BST
Output voltage of boost converter.
E3
VOP
Positive terminal output.
B3, E1
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DS4801T-01
January 2022
RT4801T
Functional Block Diagram
BST
LXP
UVLO
VIN
OVP
Bandgap
Reference
SCP1
VREF
LDO
VOP
-1x
Charge Pump
CF1
P1
PWM
Logic
N1
GM
+
DAC
RP2
OCP1
VREF
RP1
Oscillator
ENP
CF2
Soft-Start
ENN
2
VON
I C
SCL
RN2
SDA
SCP2
-
PGND
Fast
Discharge
+
VOP
VON
DAC
RN1
GND
VREF
Operation
The RT4801T is a highly integrated Boost, LDO and
interface. The RT4801T provides Over-Temperature
inverting charge pump to generate positive and
Protection (OTP) and Short Circuit Protection (SCP)
negative output voltages for LCD panel bias or
mechanisms to prevent the device from damage with
consumer products. It can support input voltage range
abnormal operations. When the EN voltage is logic low
from 2.5V to 5.5V and the output current up to 150mA.
for more than 375s, the IC will be shut down with low
Both
input supply current less than 1A.
positive
and
negative
voltages
can
be
programmed by a MCU through the dedicated
I 2C
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January 2022
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RT4801T
Absolute Maximum Ratings (Note 1)
VIN, BST, VOP, ENP, ENN, CF1, LXP, SCL and SDA -------------------------------------------------------- 0.3V to 7V
LXP (< 100ns) ---------------------------------------------------------------------------------------------------------- 2.4V to 10.7V
VON and CF2 ---------------------------------------------------------------------------------------------------------- 7V to 0.3V
Power Dissipation, PD @ TA = 25°C
WL-CSP-15B 1.31x2.07 (BSC) ----------------------------------------------------------------------------------- 2.00W
Package Thermal Resistance (Note 2)
WL-CSP-15B 1.31x2.07 (BSC), JA ----------------------------------------------------------------------------- 49.8°C/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 Input Voltage ------------------------------------------------------------------------------------------------- 2.5V to 5.5V
Ambient Temperature Range -------------------------------------------------------------------------------------- 40C to 85C
Junction Temperature Range -------------------------------------------------------------------------------------- 40C to 125C
Electrical Characteristics
(VIN = 3.7V, CIN = COP = CF1 = 4.7F, CBST = CON1= CON2 = 10F, L1 = 2.2H, TA = 25°C, unless otherwise specified.)
Parameter
Symbol
Test Conditions
Min
Typ
Max
Unit
2.5
--
5.5
V
Power Supply
Input Voltage Range
VIN
Under Voltage Lockout
Threshold Voltage
VUVLO_H
VIN Rising
--
--
2.5
VUVLO_L
VIN Falling
--
--
2.3
Over-Temperature Protection
TOTP
(Note 5)
--
140
--
°C
Over-Temperature Protection
Hysteresis
TOTP_HYST
(Note 5)
--
15
--
°C
Shut Down Current
ISHDN
ENP = ENN = 0V
--
--
1
A
V
Boost Converter
Boost Voltage Range
VBST
4.15
--
6.2
V
Peak Current Limit
IOCP
--
1.3
--
A
Boost Switching Frequency
fOSC_P
0.8
1
1.2
MHz
6
V
LDO
Positive Output Voltage Range
Positive Output Voltage Setting
VOP_SET
Range
Positive Output Voltage
Accuracy
4
VOP
Per step
VOP_ACC
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4
--
100
--
mV
1
--
1
%
is a registered trademark of Richtek Technology Corporation.
DS4801T-01
January 2022
RT4801T
Parameter
Symbol
Test Conditions
Min
Typ
Max
Unit
--
--
150
mA
Positive Output Current
Capability
IOP_MAX
Dropout Voltage
VOP_DROP
VBST = 5.4V, VOP = 5.4V,
IOP = 100mA
--
--
150
mV
Line Regulation
VLINE_OP
VIN = 2.5 to 5.5V, IOP = 40mA
--
2
--
mV
Load Regulation
VLOAD_OP IOP = 80mA
--
3
--
%/A
Short Circuit Protection Current IOP_SC
--
250
--
mA
Fast Discharge Resistance
RDISP
--
70
--
Negative Output Voltage
Range
VON
4
--
6
V
Negative Output Voltage
Setting Range
VON_SET
--
100
--
mV
Negative Output Voltage
Accuracy
VON_ACC
1
--
1
%
Negative Output Current
Capability
ION_MAX
--
--
150
mA
Negative Charge Pump
Switching Frequency
fOSC_N
0.8
1
1.2
MHz
Line Regulation
VLINE_ON
--
10
--
mV
Load Regulation
VLOAD_ON ION = 80mA
--
6
--
%/A
Short Circuit Protection Level
VON_SC
--
75
--
%
Fast Discharge Resistance
RDISN
--
20
--
Negative Charge Pump
Per step
VIN = 2.5 to 5.5V, ION = 40mA
Percentage of target value
Logic Input (ENP, ENN, SCL, SDA)
Input Threshold
Voltage
Logic-High
VIH
VIN =2.5V to 5.5V
1.2
--
--
Logic-Low
VIL
VIN =2.5V to 5.5V
--
--
0.4
--
200
--
k
--
0.5
--
A
ENP, ENN Pull-down
Resistance
REN
SDA, SCL Sink Current
IIH
SDA, SCL Logic
Input Voltage
VSDA , VSCL = 3V
Low-Level
VSCL_L
--
--
0.4
High-Level
VSCL_H
1.2
--
--
V
V
SCL Clock Frequency
fCLK
--
--
400
kHz
Output Fall Time
tFL2COUT
--
--
250
ns
Bus Free Time Between
Stop/Start
tBUF
1.3
--
--
s
Hold Time Start Condition
tHD,STA
0.6
--
--
s
Setup Time for Start Condition
tSU,STA
0.6
--
--
s
SCL Low Time
tLOW
1.3
--
--
s
SCL High Time
tHIGH
0.6
--
--
s
Data Setup Time
tSU,DAT
100
--
--
ns
Data Hold Time
tHD,DAT
0
--
900
ns
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DS4801T-01
January 2022
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5
RT4801T
Parameter
Setup Time for Stop Condition
Symbol
Test Conditions
tSU,STO
Min
Typ
Max
Unit
0.6
--
--
s
Note 1. Stresses beyond those under 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 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.
Note 5. TOTP, TOTP_HYST are guaranteed by design.
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DS4801T-01
January 2022
RT4801T
Typical Application Circuit
L1
2.2μH
RT4801T
C1
VIN
2.5V to 5.5V
CIN
4.7μF
B1
A1
B2
C2
VIN
LXP
VOP
ENP
VON
ENN
D1
E3
COP
4.7μF
A2
CON1
10μF
CON2*
10μF
RON*
VON
4V to 6V
BST D3, E2
CBST
10μF
SCL
CF1
SDA
PGND
ROP*
VOP
4V to 6V
CF2
GND
B3, E1
C3
A3
CF1
4.7μF
D2
* : (1) ROP and RON should be paralleled with VOP and VON if output continuous
discharge is required when channel is powered off.
(2) CON2 is suggest to be paralleled with CON1 to get better performance when
output 150mA application.
Table 1. Component List of Evaluation Board
Reference
Qty
Part Number
Description
Package
Supplier
CIN, COP, CF1
1
GRM188R61C475KAAJ
4.7F/16V/X5R
0603
Murata
CBST, CON1, CON2
1
GRM188R61C106KAAL
10F/16V/X5R
0603
Murata
L1
1
1269AS-H-2R2N=P2
2.2H/130m
2.5 x 2.0 x 1.0mm
Toko
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January 2022
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RT4801T
I2C Interface
SDA
VIH(MIN)
VIL(MAX)
tSU,DAT
tLOW
tHD,DAT
tSU,STO
tBUF
tHIGH
SCL VIH(MIN)
VIL(MAX)
tHD,STA
tF
S
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P
S
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DS4801T-01
January 2022
RT4801T
I2C Command
Slave Address
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0 = LSB
1
1
1
0
0
1
1
R/W
Write Command
(a) Write single byte of data to Register
Slave Address
Start
1
1
1
0
0
1
1
0
Register Address
Data From Master
Slave R7 R6 R5 R4 R3 R2 R1 R0 Slave D7 D6 D5 D4 D3 D2 D1 D0 Slave Stop
ACK
ACK
ACK
(b) Write multiple bytes of data to Registers
Slave Address
Start
1
1
1
0
0
1
Register Address nth
nth Data From Master
Slave
Slave
0
R7 R6 R5 R4 R3 R2 R1 R0
D7 D6 D5 D4 D3 D2 D1 D0 Slave
ACK
ACK
ACK
1
Last Data From Master
(n + 1)th Data From Master
D7 D6 D5 D4 D3 D2 D1 D0 Slave
ACK
D7 D6 D5 D4 D3 D2 D1 D0 Slave Stop
ACK
Read Command
(a) Read single byte of data from Register
Slave Address
Start
1
1
1
0
0
Register Address
1
1
0 Slave D7 D6 D5 D4 D3 D2 D1 D0 Slave
ACK
ACK
1
1 Slave D7 D6 D5 D4 D3 D2 D1 D0 Master Stop
ACK
NACK
Slave Address
Restart
1
1
1
0
0
Data From Master
1
(b) Read multiple bytes of data from Registers
Slave Address
Start 1
1
1
0
0
1
Register Address
1
0
Slave D7 D6 D5 D4 D3 D2 D1 D0 Slave
ACK
ACK
1
Slave D7 D6 D5 D4 D3 D2 D1 D0 Master
ACK
ACK
Slave Address
Restart
1
1
1
0
0
1
nth Data From Master
1
Last Data From Master
D7 D6 D5 D4 D3 D2 D1 D0 Master Stop
NACK
Start : Start command
ACK : Acknowledge = L active
R7 to R0 : Register Address.
D7 to D0 : Write data when WRITE command or read
VOP : Register address = 0X00h
data when READ command
VON : Register address = 0X01h
Stop : Stop command
DISP : Register address = 0x03h
DISN : Register address = 0x03h
APPS : Register address = 0x03h
R/W : Read active (R/W = H) or Write active (R/W = L)
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January 2022
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RT4801T
Registers Map
Table 2. VOP Voltage Selection
Name
Register
DATA
Address
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
VOP(V)
VOP
00h
00h
Reserved Reserved Reserved
0
0
0
0
0
4
VOP
00h
01h
Reserved Reserved Reserved
0
0
0
0
1
4.1
VOP
00h
02h
Reserved Reserved Reserved
0
0
0
1
0
4.2
VOP
00h
03h
Reserved Reserved Reserved
0
0
0
1
1
4.3
VOP
00h
04h
Reserved Reserved Reserved
0
0
1
0
0
4.4
VOP
00h
05h
Reserved Reserved Reserved
0
0
1
0
1
4.5
VOP
00h
06h
Reserved Reserved Reserved
0
0
1
1
0
4.6
VOP
00h
07h
Reserved Reserved Reserved
0
0
1
1
1
4.7
VOP
00h
08h
Reserved Reserved Reserved
0
1
0
0
0
4.8
VOP
00h
09h
Reserved Reserved Reserved
0
1
0
0
1
4.9
VOP
00h
0Ah
Reserved Reserved Reserved
0
1
0
1
0
5
VOP
00h
0Bh
Reserved Reserved Reserved
0
1
0
1
1
5.1
VOP
00h
0Ch
Reserved Reserved Reserved
0
1
1
0
0
5.2
VOP
00h
0Dh
Reserved Reserved Reserved
0
1
1
0
1
5.3
VOP
00h
0Eh
Reserved Reserved Reserved
0
1
1
1
0
5.4
VOP
00h
0Fh
Reserved Reserved Reserved
0
1
1
1
1
5.5
VOP
00h
10h
Reserved Reserved Reserved
1
0
0
0
0
5.6
VOP
00h
11h
Reserved Reserved Reserved
1
0
0
0
1
5.7
VOP
00h
12h
Reserved Reserved Reserved
1
0
0
1
0
5.8
VOP
00h
13h
Reserved Reserved Reserved
1
0
0
1
1
5.9
VOP
00h
14h
Reserved Reserved Reserved
1
0
1
0
0
6
Table 3. VON Voltage Selection
Name
Register
DATA
Address
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
VON(V)
VON
01h
00h
Reserved
Reserved
Reserved
0
0
0
0
0
-4
VON
01h
01h
Reserved
Reserved
Reserved
0
0
0
0
1
-4.1
VON
01h
02h
Reserved
Reserved
Reserved
0
0
0
1
0
-4.2
VON
01h
03h
Reserved
Reserved
Reserved
0
0
0
1
1
-4.3
VON
01h
04h
Reserved
Reserved
Reserved
0
0
1
0
0
-4.4
VON
01h
05h
Reserved
Reserved
Reserved
0
0
1
0
1
-4.5
VON
01h
06h
Reserved
Reserved
Reserved
0
0
1
1
0
-4.6
VON
01h
07h
Reserved
Reserved
Reserved
0
0
1
1
1
-4.7
VON
01h
08h
Reserved
Reserved
Reserved
0
1
0
0
0
-4.8
VON
01h
09h
Reserved
Reserved
Reserved
0
1
0
0
1
-4.9
VON
01h
0Ah
Reserved
Reserved
Reserved
0
1
0
1
0
-5
VON
01h
0Bh
Reserved
Reserved
Reserved
0
1
0
1
1
-5.1
VON
01h
0Ch
Reserved
Reserved
Reserved
0
1
1
0
0
-5.2
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DS4801T-01
January 2022
RT4801T
Name
Register
DATA
Address
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
VON(V)
VON
01h
0Dh
Reserved
Reserved
Reserved
0
1
1
0
1
-5.3
VON
01h
0Eh
Reserved
Reserved
Reserved
0
1
1
1
0
-5.4
VON
01h
0Fh
Reserved
Reserved
Reserved
0
1
1
1
1
-5.5
VON
01h
10h
Reserved
Reserved
Reserved
1
0
0
0
0
-5.6
VON
01h
11h
Reserved
Reserved
Reserved
1
0
0
0
1
-5.7
VON
01h
12h
Reserved
Reserved
Reserved
1
0
0
1
0
-5.8
VON
01h
13h
Reserved
Reserved
Reserved
1
0
0
1
1
-5.9
VON
01h
14h
Reserved
Reserved
Reserved
1
0
1
0
0
-6
Table 4. VOP Active Discharge
Name
Register
DATA
Address
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1 Bit0
VOP
Discharge
DISP
03h
00h
Reserved APPS Reserved Reserved Reserved Reserved
0
DISN
W/O
DISP
03h
02h
Reserved APPS Reserved Reserved Reserved Reserved
1
DISN
W
Table 5. VON Active Discharge
Name
Register
DATA
Address
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1 Bit0
VON
Discharge
DISN
03h
00h
Reserved APPS Reserved Reserved Reserved Reserved DISP
0
W/O
DISN
03h
01h
Reserved APPS Reserved Reserved Reserved Reserved DISP
1
W
Table 6. Application
Name
Register
Address
DATA
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Application
APPS
03h
00h
Reserved
0
Reserved
Reserved
Reserved
Reserved
DISP
DISN
Tablet
APPS
03h
40h
Reserved
1
Reserved
Reserved
Reserved
Reserved
DISP
DISN
Smartphone
The Reserved bits are ignored when written and return either 0 or 1 when read.
Factory Default Register Value
Name
Register Address
DATA
VOP
00h
0Ah
VON
01h
0Ah
DISP
03h
43h
DISN
03h
43h
APPS
03h
43h
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January 2022
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11
RT4801T
Typical Operating Characteristics
Efficiency vs. Output Current
VOP vs. Output Current
5.02
100
80
VIN = 4.5V
70
VIN = 3.7V
60
VIN = 2.9V
5.01
VOP (V)
Efficiency (%)
90
50
40
5.00
VIN = 4.5V
VIN = 3.7V
4.99
VIN = 2.9V
30
4.98
20
10
VOP = 5V, VON = 5V
VOP = 5V
4.97
0
0
0.02
0.04
0.06
0
0.08
0.01
0.02
Output Current (A)
VON vs. Output Current
0.04
0.05
0.06
0.07
0.08
VOP vs. Input Voltage
-4.97
5.02
-4.98
5.01
-4.99
5.00
VOP (V)
VON (V)
0.03
Output Current (A)
-5.00
IOP = 0A
IOP = 40mA
4.99
IOP = 80mA
VIN = 4.5V
-5.01
4.98
VIN = 3.7V
VIN = 2.9V
VON = 5V
-5.02
VOP = 5V
4.97
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
2.5
3
3.5
Output Current (A)
4.5
5
5.5
Input Voltage (V)
VON vs. Input Voltage
Shutdown Current vs. Temperature
-4.97
0.20
VIN = 3.7V, EN = 0V
0.18
Shutdown Current (μA)
-4.98
VON (V)
4
-4.99
-5.00
ION = 80mA
-5.01
ION = 40mA
ION = 0A
VON = 5V
-5.02
0.16
0.14
0.12
0.10
0.08
0.06
0.04
0.02
0.00
2.5
3
3.5
4
4.5
5
Input Voltage (V)
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12
5.5
-40
-20
0
20
40
60
80
100
Temperature (°C)
is a registered trademark of Richtek Technology Corporation.
DS4801T-01
January 2022
RT4801T
Quiescent Current vs. Temperature
Input Voltage vs. Temperature
2.30
1.2
2.28
2.26
1.0
Input Voltage (V)
Quiescent Current (mA)
1.1
0.9
0.8
0.7
0.6
UVLO Rising
2.24
2.22
2.20
2.18
2.16
UVLO Falling
2.14
0.5
2.12
VIN = 3.7V
0.4
-40
-20
0
20
40
60
80
100
2.10
-40
0
20
40
60
Temperature (°C)
Temperature (°C)
VOP Ripple Voltage
VOP Ripple Voltage
80
100
VOP
(10mV/Div)
VOP
(10mV/Div)
VIN = 3.7V, VOP = 5V, IOP = 0mA
VIN = 3.7V, VOP = 5V, IOP = 20mA
Time (1ms/Div)
Time (1ms/Div)
VOP Ripple Voltage
VOP Ripple Voltage
VOP
(10mV/Div)
VOP
(10mV/Div)
VIN = 3.7V, VOP = 5V, IOP = 40mA
VIN = 3.7V, VOP = 5V, IOP = 80mA
Time (1ms/Div)
Time (1ms/Div)
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-20
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RT4801T
VON Ripple Voltage
VON
(20mV/Div)
VON Ripple Voltage
VON
(20mV/Div)
VIN = 3.7V, VON = 5V, ION = 0mA
Time (1ms/Div)
Time (10s/Div)
VON Ripple Voltage
VON Ripple Voltage
VON
(20mV/Div)
VOP
(50mV/Div)
VIN = 3.7V, VON = 5V, ION = 20mA
VON
(20mV/Div)
VIN = 3.7V, VON = 5V, ION = 40mA
VIN = 3.7V, VON = 5V, ION = 80mA
Time (10s/Div)
Time (10s/Div)
Load Transient
Load Transient
VIN = 2.9V, VOP = 5V, VON = 5V,
TR = TF = 10s, IOPN = 5m to 35mA
VOP
(50mV/Div)
VON
(50mV/Div)
VON
(50mV/Div)
IOP
(20mA/Div)
IOP
(50mA/Div)
Time (100s/Div)
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VIN = 2.9V, VOP = 5V, VON = 5V,
TR = TF = 10s, IOPN = 10m to 70mA
Time (100s/Div)
is a registered trademark of Richtek Technology Corporation.
DS4801T-01
January 2022
RT4801T
Load Transient
VOP
(50mV/Div)
VIN = 3.7V, VOP = 5V, VON = 5V,
TR = TF = 10s, IOPN = 5m to 35mA
VON
(50mV/Div)
Load Transient
VOP
(50mV/Div)
VIN = 3.7V, VOP = 5V, VON = 5V,
TR = TF = 10s, IOPN = 10m to 70mA
VON
(50mV/Div)
IOP
(20mA/Div)
IOP
(50mA/Div)
VOP
(50mV/Div)
Time (100s/Div)
Time (100s/Div)
Load Transient
Load Transient
VIN = 4.5V, VOP = 5V, VON = 5V,
TR = TF = 10s, IOPN = 5m to 35mA
VOP
(50mV/Div)
VON
(50mV/Div)
VON
(50mV/Div)
IOP
(20mA/Div)
IOP
(50mA/Div)
VIN = 4.5V, VOP = 5V, VON = 5V,
TR = TF = 10s, IOPN = 10m to 70mA
Time (100s/Div)
Time (100s/Div)
Line Transient
Line Transient
VIN = 2.9V to 3.4V, VOP = 5V,
VON = 5V, IOPN = 5mA
VIN
VIN = 3.7V to 4.2V, VOP = 5V,
VON = 5V, IOPN = 5mA
VIN
VOP
(50mV/Div)
VIN
(1V/Div)
VOP
(50mV/Div)
VIN
(1V/Div)
VON
(50mV/Div)
VON
(50mV/Div)
Time (500s/Div)
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January 2022
Time (500s/Div)
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RT4801T
Line Transient
Line Transient
VIN = 2.9V to 3.4V, VOP = 5V,
VON = 5V, IOPN = 40mA
VIN
VIN = 3.7V to 4.2V, VOP = 5V,
VON = 5V, IOPN = 40mA
VIN
VOP
(50mV/Div)
VIN
(1V/Div)
VOP
(50mV/Div)
VIN
(1V/Div)
VON
(50mV/Div)
VON
(50mV/Div)
Time (500s/Div)
Time (500s/Div)
Line Transient
Line Transient
VIN = 2.9V to 3.4V, VOP = 5V,
VON = 5V, IOPN = 80mA
VIN
VIN = 3.7V to 4.2V, VOP = 5V,
VON = 5V, IOPN = 80mA
VIN
VOP
(50mV/Div)
VIN
(1V/Div)
VOP
(50mV/Div)
VIN
(1V/Div)
VON
(50mV/Div)
VON
(50mV/Div)
Time (500s/Div)
Time (500s/Div)
Power On
Power Off
ENP
(5V/Div)
ENP
(5V/Div)
ENN
(5V/Div)
(5V/Div)
VOP
VON
ENN
(5V/Div)
(5V/Div)
VIN = 3.7V, VOP = 5V, VON = 5V,
No Load, ENP/ENN On simultaneously
IIN
(200mA/Div)
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VON
IIN
(200mA/Div)
Time (1ms/Div)
VOP
VIN = 3.7V, VOP = 5V, VON = 5V,
No Load, ENP/ENN Off simultaneously
Time (1ms/Div)
is a registered trademark of Richtek Technology Corporation.
DS4801T-01
January 2022
RT4801T
Power On
Power Off
ENP
(5V/Div)
ENP
(5V/Div)
ENN
(5V/Div)
VOP
(5V/Div)
VON
ENN
(5V/Div)
(5V/Div)
VON
VIN = 3.7V, VOP = 5V, VON = 5V,
No Load, ENP prior ENN On
VIN = 3.7V, VOP = 5V, VON = 5V,
No Load, ENP prior ENN Off
IIN
(200mA/Div)
IIN
(200mA/Div)
Time (1ms/Div)
Time (1ms/Div)
Power On
Power Off
ENP
(5V/Div)
ENP
(5V/Div)
ENN
(5V/Div)
ENN
(5V/Div)
VOP
(5V/Div)
VON
(5V/Div)
IIN
(200mA/Div)
VOP
VON
VIN = 3.7V, VOP = 5V, VON = 5V,
No Load, ENN prior ENP On
VIN = 3.7V, VOP = 5V, VON = 5V,
No Load, ENN prior ENP Off
IIN
(200mA/Div)
Time (1ms/Div)
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DS4801T-01
VOP
January 2022
Time (1ms/Div)
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RT4801T
Application Information
The RT4801T is a highly integrated Boost, LDO and
inverting charge pump to generate positive and
negative output voltages for LCD panel bias or
consumer products. It can support input voltage range
from 2.5V to 5.5V and the output current up to 150mA.
The VOP positive output voltage is generated from the
LDO supplied from a synchronous Boost converter, and
VOP is set at a typical value of 5V. The Boost converter
output also drives an inverting charge pump controller
to generate VON negative output voltage which is set at
a typical value of 5V. Both positive and negative
voltages can be programmed by a MCU through the
dedicated I2C interface and the available voltage range
is from 4V to 6V with 100mV per step.
Input Capacitor Selection
Input ceramic capacitor with 4.7F capacitance is
suggested for applications. For better voltage filtering,
select ceramic capacitors with low ESR, X5R and X7R
types are suitable because of their wider voltage and
temperature ranges.
η VIN VOUT VIN
2
L
0.4 VOUT I OUT(MAX)fOSC
2
where fOSC is the switching frequency. For better
system performance, a shielded inductor is preferred to
avoid EMI problems.
Boost Output Capacitor Selection
The output ripple voltage is an important index for
estimating IC performance. This portion consists of two
parts. One is the product of ripple current with the ESR
of the output capacitor, while the other part is formed by
the charging and discharging process of the output
capacitor. As shown in Figure 1, VOUT1 can be
evaluated based on the ideal energy equalization.
According to the definition of Q, the VOUT1 value can
be calculated as the following equation :
Q = IOUT D 1 = COUT VOUT1
fSOC
IOUT D
VOUT1 =
fSOC COUT
Boost Inductor Selection
where fOSC is the switching frequency and D is the duty
The inductance depends on the maximum input current.
cycle.
As a general rule, the inductor ripple current range is
Finally, taking ESR into consideration, the overall output
20% to 40% of the maximum input current. If 40% is
ripple voltage can be determined by the following
selected as an example, the inductor ripple current can
equation :
be calculated according to the following equations :
VOUT IOUT(MAX)
VIN
IRIPPLE = 0.4 IIN(MAX)
IIN(MAX) =
where η is the efficiency of the VOP Boost converter,
VOUT = VESR + VOUT1 = VSER +
IOUT D
fOSC COUT
where VESR = ICrms x RCESR
The output capacitor, COUT, should be selected
accordingly.
IIN(MAX) is the maximum input current, and IL is the
inductor ripple current. The input peak current can then
be obtained by adding the maximum input current with
half of the inductor ripple current as shown in the
following equation :
IPEAK = 1.2 x IIN(MAX)
Note that the saturated current of the inductor must be
greater than IPEAK.
The inductance can eventually be determined according
to the following equation :
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is a registered trademark of Richtek Technology Corporation.
DS4801T-01
January 2022
RT4801T
be paralleled with the output. In shut down mode, the
input supply current for the IC is less than 1A.
IL
Input Current
Over-Current Protection
Inductor Current
The RT4801T includes a cycle-by-cycle current limit
function which monitors the inductor current during
each ON period. The power switch will be forced off to
avoid large current damage once the current is over the
Output Current
Time
limit level.
Output Short Circuit Protection
DTs
Output Ripple (ac)
Time
VOUT1
The RT4801T has an advanced output short-circuit
protection mechanism which prevents the IC from
damage by unexpected applications.
VOP short to ground
When the output current is higher than the current
Figure 1. The Output Ripple Voltage without the
limit level 250mA (typ.) for 1ms (typ.), both VPOS and
Contribution of ESR
VON outputs shut down and only can re-start to
normal operation after re-toggling the ENP/ENN pin.
Under Voltage Lockout
To prevent abnormal operation of the IC in low voltage
VON short to ground
condition, an under voltage lockout is included which
The RT4801T activates short-circuit protection once
shuts down IC operation when input voltage is lower
the VON voltage drops below 75% (typ.) of target
than the specified threshold voltage.
voltage due to excessive loading. The protection
stops after the VON voltage backs to higher than the
Soft-Start
protection level for 1ms (typ.). There is not any
The RT4801T employs an internal soft-start feature to
influence on VOP.
avoid high inrush current during start-up. The soft-start
function is achieved by clamping the output voltage of
Over-Temperature Protection
the internal error amplifier with another voltage source
The RT4801T equips an over-temperature protection
that is increased slowly from zero to near VIN during the
circuitry to prevent overheating due to excessive power
soft-start period.
dissipation. The OTP will shut down LCD bias operation
when ambient temperature exceeds 140°C. Once the
Output Voltage Setting
ambient temperature cools down by approximately
The output voltage of WL-CSP package can be
15°C, IC will automatically resume normal operation. To
I 2C
maintain continuous operation, the maximum junction
interface according to the VOP/VON Voltage Selection
temperature should be prevented from rising above
Table.
125°C.
Shut Down Delay and Discharge
Thermal Considerations
When the EN signal is logic low for more than 375s,
The junction temperature should never exceed the
the output will be powered off. When the output
absolute maximum junction temperature TJ(MAX), listed
discharge function is selected, the RT4801T starts to
under Absolute Maximum Ratings, to avoid permanent
discharge the output voltage to ground with 20ms
damage to the device. The maximum allowable power
duration and then the output goes back to floating state.
dissipation depends on the thermal resistance of the IC
If the output continuous discharge function is required
package, the PCB layout, the rate of surrounding airflow,
for application, the external resistor is recommended to
and the difference between the junction and ambient
programmed by a MCU through the dedicated
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RT4801T
temperatures. The maximum power dissipation can be
Layout Considerations
calculated using the following formula :
For the best performance of the RT4801T, the following
PD(MAX) = (TJ(MAX) - TA) / JA
PCB layout guidelines should be strictly followed.
where TJ(MAX) is the maximum junction temperature, TA
is
the
ambient
temperature,
JA
and
is
the
as close to the IC as possible. The traces should
junction-to-ambient thermal resistance.
be wide and short especially for the high current
For continuous operation, the maximum operating
output loop.
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-15B 1.31x2.07 (BSC) package, the
thermal resistance, JA, is 49.8°C/W on a standard
JEDEC
51-7
high
For good regulation, place the power components
The input and output bypass capacitor should be
placed as close to the IC as possible and
connected to the ground plane of the PCB.
effective-thermal-conductivity
The flying capacitor should be placed as close to
the CF1/CF2 pin as possible to avoid noise
four-layer test board. The maximum power dissipation
injection.
at TA = 25°C can be calculated as below :
PD(MAX) = (125°C - 25°C) / (49.8°C/W) = 2W for a
Minimize the size of the LXP node and keep the
WL-CSP-15B 1.31x2.07 (BSC) package.
traces wide and short. Care should be taken to
The maximum power dissipation depends on the
avoid running traces that carry any noise-sensitive
operating ambient temperature for the fixed T J(MAX) and
signals near LXP or high-current traces.
the thermal resistance, JA. The derating curves in
Figure 2 allows the designer to see the effect of rising
ambient
temperature
on
the
maximum
power
Separate power ground (PGND) and analog
ground (GND). Connect the GND and the PGND
islands at a single end. Make sure that there are
dissipation.
no other connections between these separate
Maximum Power Dissipation (W)1
3.0
Four-Layer PCB
ground planes.
2.5
2.0
1.5
1.0
0.5
0.0
0
25
50
75
100
125
Ambient Temperature (°C)
Figure 2. Derating Curve of Maximum Power
Dissipation
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is a registered trademark of Richtek Technology Corporation.
DS4801T-01
January 2022
RT4801T
ENN
ENP
SCL
SDA
VOP
COP
CIN
ENN
VBAT
VON
CF2
ENP
SCL
PGND
VIN
SDA
LXP
GND
BST
PGND
BST
VOP
CF1
CF1
L1
CBST
CON
VON
Figure 3. PCB Layout Guide
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RT4801T
Outline Dimension
Dimensions In Millimeters
Dimensions In Inches
Symbol
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
2.020
2.120
0.080
0.083
D1
E
1.600
1.260
0.063
1.360
0.050
0.054
E1
0.800
0.031
e
0.400
0.016
WL-CSP-15B 1.31x2.07 (BSC)
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is a registered trademark of Richtek Technology Corporation.
DS4801T-01
January 2022
RT4801T
Footprint Information
Package
Number of
Pin
Footprint Dimension (mm)
Type
Tolerance
e
NSMD
WL-CSP1.31x2.07-15(BSC)
15
A
B
0.240
0.340
0.270
0.240
0.400
SMD
±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.
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