RT4813
High Efficiency Boost Converter
General Description
The RT4813 allows systems to take advantage of new
battery chemistries that can supply significant energy
when the battery voltage is lower than the required
voltage for system power ICs. By combining built-in
power transistors, synchronous rectification, and low
supply current; this IC provides a compact solution for
systems using advanced Li-Ion battery chemistries.
The RT4813 is a boost regulator designed to provide a
minimum output voltage from a single-cell Li-Ion battery,
even when the battery voltage is below system
minimum. In boost mode, output voltage regulation is
guaranteed to a maximum load current of 3.1A.
Quiescent current in Shutdown Mode is less than 1A,
which maximizes battery life.
Features
CMCOT Topology and Small Output Ripple when
VIN Close VOUT Voltage
Operates from a Single Li-ion Cell : 1.8V to 5.5V
Adjustable Output Voltage : 1.8V to 5.5V
PSM Operation
Up to 96% Efficiency
Input Over Current Limit
Input / Output Over Voltage Protection
Programmable Average Output Current Limit
Range : 3100mA to 550mA
Internal Compensation
Output Discharge
Output Short Protection
True Load Disconnect
Ordering Information
RT4813
Package Type
QUF : UQFN-9L 2x2 (FC) (U-Type)
Lead Plating System
G : Green (Halogen Free and Pb Free)
Note :
Richtek products are :
Applications
Single-Cell Li-Ion, LiFePO4 Smart-Phones
Portable Equipment
Marking Information
3V : Product Code
W : Date Code
3VW
RoHS compliant and compatible with the current
requirements of IPC/JEDEC J-STD-020.
Suitable for use in SnPb or Pb-free soldering
processes.
Simplified Application Circuit
L1
V
IN
C1
VIN
C2
SCL
SDA
GND
FB
R2
EN
R3
EN
SW
RT4813
VOUT
R1
C3
V
OUT
I
2
C Control
Copyright © 2017 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS4813-06
September
2017
www.richtek.com
1
RT4813
Pin Configuration
(TOP VIEW)
SCL
EN
VOUT
SW
PGND
1
2
3
4
9
8
7
6
5
VIN
FB
GND
SDA
UQFN-9L 2x2 (FC)
Functional Pin Description
Pin No.
1
2
3
4
5
6
7
8
9
Pin Name
EN
VOUT
SW
PGND
SDA
GND
FB
VIN
SCL
Pin Function
Enable input (1 enabled, 0 disabled), must not be left floating.
Boost converter output.
Switching node.
Power ground.
I
2
C interface data input.
Analog ground.
Voltage feedback.
Power input. Input capacitor CIN must be placed as close to IC as possible.
I
2
C interface clock input.
Functional Block Diagram
VIN
Gate
DRV
VOUT
OCP
SW
SDA
SCL
EN
Digital
CTRL
PWM
CTRL
AMP
-
+
FB
OSC
PGND
OTP
UVLO
VREF
GND
Copyright © 2017 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
2
DS4813-06
September
2017
RT4813
Operation
The RT4813 combined built-in power transistors,
synchronous rectification, and low supply current, it
provides a compact solution for system using advanced
Li-Ion battery chemistries.
In boost mode, output voltage regulation is guaranteed to
a maximum load current of 3.1A. Quiescent current in
Shutdown mode is less than 1A, which maximizes
battery life.
Startup and Shutdown State
When V
IN
is rising and through the LIN state, it will
enter the Startup state. If EN is pulled low, any function
is turned-off in shutdown mode.
Soft-Start State
It starts to switch in Soft-start state. After the LIN state,
output voltage is rising with the internal reference
voltage.
Depiction
Linear startup 1
Linear startup 2
Boost soft-start
Boost mode
Condition
V
IN
> V
OUT
V
IN
> V
OUT
V
OUT
< V
OUT(MIN)
V
OUT
= V
OUT(MIN)
Fault State
As the Figure 1 shown, it will enter to the Fault state as
below,
Mode
LIN
LIN 1
LIN 2
Soft-Start
Boost
LIN State
The timeout of LIN2 is over the 1024s.
It will be the high impedance between the input and
output when the fault is triggered. A restart will be start
after 20ms.
When V
IN
is rising, it enters the LIN State. There are
two parts for the LIN state. It provides maximum current
for 1A to charge the C
OUT
in LIN1, and the other one is
for 2A in LIN2. By the way, the EN is pulled high and
V
IN
> UVLO.
As the figure shown, if the timeout is over the
specification, it will enter the Fault mode.
EN = 1,
Vin > UVLO
OCP
The converter senses the current signal when the
high-side P-MOSFET turns on. As a result, the OCP is
cycle by-cycle current limitation. If the OCP occurs, the
converter holds off the next on pulse until inductor
current drops below the OCP limit.
OTP
The converter has an over-temperature protection.
When the junction temperature is higher than the
thermal shutdown rising threshold, the system will be
LIN 1
Timeout < 512μs
Timeout > 512μs
Soft-Start
Timeout
< 1024μs
Boost
mode
LIN 2
Timeout > 1024μs
Fault
State
latched and the output voltage will no longer be
regulated until the junction temperature drops under
the falling threshold.
Figure 1. RT4813 State Chart
Copyright © 2017 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS4813-06
September
2017
www.richtek.com
3
RT4813
Absolute Maximum Ratings
(Note 1)
VIN, FB, EN, SDA, SCL to GND -----------------------------------------------------------------------------------
0.2V
to 6V
SW to GND -------------------------------------------------------------------------------------------------------------
0.2V
to 6V
< 20ns --------------------------------------------------------------------------------------------------------------------
2V
to 9.4V
VOUT to GND ----------------------------------------------------------------------------------------------------------
6V
Power Dissipation, P
D
@ T
A
= 25C
UQFN-9L 2x2 (FC) ----------------------------------------------------------------------------------------------------
0.89W
Package Thermal Resistance
(Note 2)
UQFN-9L 2x2 (FC),
JA
----------------------------------------------------------------------------------------------
111.5C/W
UQFN-9L 2x2 (FC),
JC
----------------------------------------------------------------------------------------------
19.6 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)
Input Voltage Range --------------------------------------------------------------------------------------------------
1.8V
to 5.5V
Output Voltage Range -----------------------------------------------------------------------------------------------
1.8V
to 5.5V
Ambient Temperature Range---------------------------------------------------------------------------------------
40C
to 85C
Junction Temperature Range --------------------------------------------------------------------------------------
40C
to 125C
Electrical Characteristics
(V
IN
= 3.6V, T
A
= 25C, unless otherwise specified)
Parameter
Under Voltage Lockout
Rising Threshold
Under Voltage Lockout
Falling Threshold
FB Voltage
VOUT Voltage (I
2
C)
Shutdown Current
Quiescent Current
Pre-Charge Current
Switching Frequency
Valley Current Limit
High Side Switch R
ON
Low Side Switch R
ON
FB Pin Input Leakage
Leakage of SW
Symbol
V
UVLOR
V
UVLOF
V
FB
V
OUT
I
SHDN
I
Pre
f
SW
I
OC
V
IN
= 5V
V
IN
= 5V
I
FB
I
SW
CCM
CCM
EN = 0V
Test Conditions
Min
1.6
1.5
0.495
1
--
--
--
Typ
1.7
1.6
0.5
0
0.1
120
1
0.5
6
43
26
--
--
Max
1.8
1.7
0.505
1
2
--
--
--
--
55
35
1
5
Unit
V
V
V
%
A
A
A
MHz
A
m
m
A
A
Close loop, no load
V
OUT
V
IN
> 1V, CCM
--
--
--
--
1
--
Copyright © 2017 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
4
DS4813-06
September
2017
RT4813
Parameter
Line Regulation
Load Regulation
Output Over Voltage
Protection
Average Output Current
Limit
EN Input
Voltage
Low-Level
High-Level
Symbol
V
OUT, LINE
V
OUT, LOAD
V
OVP
I
LM
V
IL
V
IH
V
IN
= 3.6V (Default)
Test Conditions
CCM, V
IN
= 2.7V to 4.5V,
V
OUT
= 5V, I
OUT
= 500mA
CCM, I
OUT
< 3.1A, V
IN
= 3.6V,
V
OUT
= 5V
Min
--
--
--
--
--
1.2
--
T
SD
T
SD
--
--
Typ
0.5
0.5
6
3.4
--
--
0.1
160
30
Max
--
--
--
--
0.4
--
1
--
--
Unit
%
%
V
A
V
V
A
C
C
EN Sink Current
Thermal Shutdown
Thermal Shutdown
Hysteresis
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 at T
A
= 25C on a high effective thermal conductivity four-layer test board per JEDEC 51-7.
JC
is
measured at the exposed pad of the package.
Note 3.
Devices are ESD sensitive. Handling precaution recommended.
Note 4.
The device is not guaranteed to function outside its operating conditions.
Copyright © 2017 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS4813-06
September
2017
www.richtek.com
5
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