Boost Converter. RT4812 Datasheet

RT4812 Converter. Datasheet pdf. Equivalent

RT4812 Datasheet
Recommendation RT4812 Datasheet
Part RT4812
Description High Efficiency Boost Converter
Feature RT4812; RT4812 High Efficiency Boost Converter General Description The RT4812 allows systems to take advan.
Manufacture Richtek Technology
Datasheet
Download RT4812 Datasheet




Richtek Technology RT4812
RT4812
High Efficiency Boost Converter
General Description
The RT4812 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 RT4812 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 2.1A.
Quiescent current in Shutdown Mode is less than 1A,
which maximizes battery life.
Ordering Information
RT4812
Package Type
J8F : TSOT-23-8 (FC)
Lead Plating System
G : Green (Halogen Free and Pb Free)
Note :
Richtek products are :
RoHS compliant and compatible with the current
requirements of IPC/JEDEC J-STD-020.
Suitable for use in SnPb or Pb-free soldering processes.
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
Boost Current Limit
Output Over Voltage Protection
Pin Adjustable Average Output Current Limit
Threshold (2 Levels)
Internal Compensation
Output Discharge
Output Short Protection
True Load Disconnect
Applications
Single-Cell Li-Ion, LiFePO4 Smart-Phones
Portable Equipment
Marking Information
0L=DNN
0L= : Product Code
DNN : Date Code
Simplified Application Circuit
RT4812
L1
VIN SW VOUT
VOUT
C1
R1 C3
VIN
C2
FB
R2
EN
R3 H/L
ILIM
GND
Copyright © 2019 Richtek Technology Corporation. All rights reserved.
DS4812-07 March 2019
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
1



Richtek Technology RT4812
RT4812
Pin Configuration
(TOP VIEW)
87 6 5
2 34
TSOT-23-8 (FC)
Functional Pin Description
Pin No.
Pin Name
Pin Function
1 VIN
2 FB
Power input. Input capacitor CIN must be placed as close to IC as possible.
Voltage feedback.
3 VOUT Boost converter output.
4 PGND Power ground.
5 GND
Analog ground.
6 SW
Switching node.
7 EN
Enable input (1 enabled, 0 disabled), must not be floating.
8 ILIM
Average output current limit control pin. (H/L)
Functional Block Diagram
VIN
ILIM
OCP
Gate
DRV
SW Control
VOUT
SW
EN
PGND
Digital
CTRL
PWM
CTRL
OSC
OTP
UVLO
AMP -
+
VREF
FB
GND
Copyright © 2019 Richtek Technology Corporation. All rights reserved.
www.richtek.com
2
is a registered trademark of Richtek Technology Corporation.
DS4812-07 March 2019



Richtek Technology RT4812
Operation
The RT4812 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 2.1A. Quiescent current in
Shutdown mode is less than 1A, which maximizes
battery life.
Mode
LIN 1
LIN
LIN 2
Soft-Start
Boost
Depiction
Linear startup 1
Linear startup 2
Boost soft-start
Boost mode
Condition
VIN > VOUT
VIN > VOUT
VOUT < VOUT(MIN)
VOUT = VOUT(MIN)
LIN State
When VIN is rising, it enters the LIN State. There are
two parts for the LIN state. It provides maximum
current for 1A to charge the COUT in LIN1, and the
other one is for 3A in LIN2. By the way, the EN is
pulled high and VIN > UVLO.
As the figure shown, if the timeout is over the
specification, it will enter the Fault mode.
EN = 1,
Vin > UVLO
LIN 1
Timeout < 512μs
Timeout > 512μs
Soft-Start
LIN 2
Timeout
< 1024μs
Timeout > 1024μs
Boost
mode
Fault
State
Figure 1. RT4812 State Chart
RT4812
Startup and Shutdown State
When VIN 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.
Fault State
As the Figure 1 shown, it will enter to the Fault state
as below,
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.
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
latched and the output voltage will no longer be
regulated until the junction temperature drops under
the falling threshold.
Copyright © 2019 Richtek Technology Corporation. All rights reserved.
DS4812-07 March 2019
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
3







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