RT8032
1.2MHz/1.2A Buck Converter with Programmable Average
Input Current Limit
General Description
The RT8032 is a synchronous, step-down DC/DC converter
with input current limit function. The average input current
limit can be programmed by an external resistor. Its input
voltage range is from 3V to 5.5V and provides an adjustable
regulated output voltage from 0.8V to 5V while delivering
up to 1.2A of output current. The internal synchronous
low on-resistance power switches increase efficiency and
eliminate the need for an external Schottky diode. Current
mode operation with external compensation allows the
transient response to be optimized over a wide range of
loads and output capacitors.
The RT8032 is operated in forced continuous PWM Mode
which minimizes ripple voltage and reduces the noise and
RF interference. The 100% duty cycle in Low Dropout
Operation can maximize the battery life.
Features
Programmable Average Input Current Limit
3V to 5.5V Input Range
1.2A Output Current
Up to 95% Efficiency
1.2MHz Switching Frequency
No Schottky Diode Required
Force Continues Mode Operation
Low R
DS(ON)
Internal Switches : 230mΩ
Ω
Small 12-Lead WDFN Package
External Compensation for Optimal Transient
Response
External Soft-Start
Input Over Voltage Protection
RoHS Compliant and Halogen Free
Ordering Information
RT8032
Package Type
QW : WDFN-12L 4x3 (W-Type)
Lead Plating System
G : Green (Halogen Free and Pb Free)
Note :
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.
Applications
Distributed Power Systems
Battery Charger
DSL Modems
Pre-Regulator for Linear Regulators
3G/3.5G Data Card
Pin Configurations
(TOP VIEW)
SHDN/SS
NC
GND
SW
PGND
VOUT
1
2
3
4
5
6
12
11
10
9
8
7
Marking Information
For marking information, contact our sales representative
directly or through a Richtek distributor located in your
area.
13
FB
COMP
ISET
VIN
VOUT
NC
WDFN-12L 4x3
DS8032-02 March 2011
PGND
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1
RT8032
Typical Application Circuit
RT8032
V
IN
R
SS
1Meg
C
SS
57nF
10 ISET
C
C1
680nF
R
C1
1k
R
LIM
24k
PGND
C
C2
1.1nF
5, Exposed Pad (13)
C
IN
10µF
1 SHDN/SS
9 VIN
SW
4
L
4.7µH
R1
112k
R
C
C
C
120k 60nF
R2
32k
VOUT 6, 8
FB 12
COMP
11
V
OUT
3.6V
C
OUT
2200nF
GND
3
Functional Pin Description
Pin No.
Pin Name
Pin Function
Shutdown and Soft-Start Control Input. Connect this pin to a supply voltage that is
>1.4V to enable the IC and to a supply voltage that is <0.4V to shutdown the IC. An
SHDN/SS
RC network from the shutdown command signal to the pin will provide a soft-start
function by the rising time of the FB pin
NC
GND
SW
No Internal Connection.
Ground. Return the feedback resistive dividers to this ground, which in turn
connects to PGND at one point.
Internal Power MOSFET Switches Output. Connect this pin to the output inductor.
Power Ground. The exposed pad must be soldered to a large PCB and connected
to PGND for maximum power dissipation.
Output of the Converter. A filter capacitor is placed from V
OUT
to GND.
Power Input. Internal VCC for the IC. A 10μF ceramic capacitor is recommended
as close as to VIN and GND as possible
Average Input Current Limit Setting. Place a resistor and capacitor in parallel from
the pin to GND
Error Amplifier Output. The current comparator threshold increases with the control
voltage. Connect external compensation elements to the Pin to stabilize the control
loop.
Feedback Input. Receives the feedback voltage from a resistive divider connected
across the output.
1
2, 7
3
4
5,
PGND
13 (Exposed Pad)
6, 8
9
10
11
12
VOUT
VIN
ISET
COMP
FB
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2
DS8032-02 March 2011
RT8032
Function Block Diagram
Current Sense
Slope
Com
SHDN/SS
Soft-Start
V
REF
OSC
+
-
Error
Amplifier
-
+
VOUT
VIN
OC
Limit
+
-
COMP
0.4V
FB
VIN
0.95V
GND
+
-
+
-
Driver
PWM Control
SW
PGND
Input Current
Limit Setting
OTP
ISET
DS8032-02 March 2011
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3
RT8032
Absolute Maximum Ratings
(Note 1)
Supply Input Voltage, V
IN
----------------------------------------------------------------------------------------
−0.3V
to 6V
Switching Voltage, SW ------------------------------------------------------------------------------------------
−0.3V
to (V
IN
+ 0.3V)
Other I/O Pin Voltages -------------------------------------------------------------------------------------------
−0.3V
to 6V
Power Dissipation, P
D
@ T
A
= 25°C
WDFN-12L 4x3 ----------------------------------------------------------------------------------------------------- 1.667W
Package Thermal Resistance (Note 2)
WDFN-12L 4x3,
θ
JA
----------------------------------------------------------------------------------------------- 60°C/W
WDFN-12L 4x3,
θ
JC
----------------------------------------------------------------------------------------------- 7.5W
Junction Temperature --------------------------------------------------------------------------------------------- 150°C
Lead Temperature (Soldering, 10 sec.) ----------------------------------------------------------------------- 260°C
Storage Temperature Range ------------------------------------------------------------------------------------
−65°C
to 150°C
ESD Susceptibility (Note 3)
HBM (Human Body Mode) -------------------------------------------------------------------------------------- 2kV
MM (Machine Mode) ---------------------------------------------------------------------------------------------- 200V
Recommended Operating Conditions
(Note 4)
Junction Temperature Range ------------------------------------------------------------------------------------
−40°C
to 125°C
Ambient Temperature Range ------------------------------------------------------------------------------------
−40°C
to 85°C
Electrical Characteristics
(V
IN
= 5V, T
A
= 25°C, unless otherwise specified)
Parameter
Feedback Reference Voltage
DC Bias Current (PVDD, VDD
total)
Under Voltage Lockout
Threshold
Switching Frequency
Symbol
V
REF
Test Conditions
Active, Not Switching, V
FB
= 0.75V
EN =0
V
IN
Rising
V
IN
Falling
Min
0.784
--
--
2.3
2.13
1
Typ
0.8
550
--
2.43
2.29
1.2
--
--
230
230
0.45
1.9
0.1
--
Max
0.816
--
1
2.55
2.43
1.4
--
0.4
--
--
0.5
--
1
1
Unit
V
μA
μA
V
V
MHz
V
V
mΩ
mΩ
A
A
%/V
%
Logic-High Voltage V
IH
EN
Threshold Logic-Low Voltage V
IL
Switch On Resistance, High
Switch On Resistance, Low
Input Average Current Limit
Peak Current Limit
Output Voltage Line Regulation
Output Voltage Load
Regulation
R
PMOS
R
NMOS
I
AVG
I
LIM
V
EN
Rising
V
EN
Falling
I
SW
= 0.2A
I
SW
= 0.2A
R
LIM
= 25.5kΩ
V
IN
= 3V to 5.5V
0mA < I
LOAD
< 1.2A
1.4
--
--
--
0.4
1.6
--
--
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4
DS8032-02 March 2011
RT8032
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.
θ
JA
is measured in the natural convection at T
A
= 25°C on 4-layers high effective thermal conductivity 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.
DS8032-02 March 2011
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