RT6232A/B
2A, 18V, 500kHz, ACOT
TM
Step-Down Converter
General Description
The RT6232A/B is a high-efficiency, monolithic
synchronous step-down DC/DC converter that can
deliver up to 2A output current from a 4.5V to 18V input
supply. The RT6232A/B adopts ACOT architecture to
allow the transient response to be improved and keep
in constant frequency. Cycle-by-cycle current limit
provides protection against shorted outputs and soft-
start eliminates input current surge during start-up. Fault
conditions also include output under voltage protection,
output over current protection, and thermal shutdown.
Features
Integrated 210m/120m MOSFETs
4.5V to 18V Supply Voltage Range
500kHz Switching Frequency
ACOT Control
0.8V
1.5%
Voltage Reference
Adjustable Soft-Start
Power Good Indicator
Monotonic Start-Up into Pre-biased Outputs
Input Under-Voltage Lockout
Over-Current Protection and Hiccup
Ordering Information
RT6232A/B
Package Type
QW : WDFN-8L 2x3 (W-Type)
Lead Plating System
G : Green (Halogen Free and Pb Free)
UVP Option
H : Hiccup
A : PSM Mode
B : PWM Mode
Note :
Richtek products are :
Applications
Set-Top Boxes
Portable TVs
Access Point Routers
DSL Modems
LCD TVs
Marking Information
RT6232AHGQW
0V : Product Code
W : Date Code
0VW
RoHS compliant and compatible with the current
requirements of IPC/JEDEC J-STD-020.
RT6232BHGQW
0U : Product Code
W : Date Code
Suitable for use in SnPb or Pb-free soldering processes.
0UW
Simplified Application Circuit
RT6232A/B
V
IN
C
IN
LX
Enable
PGOOD
EN
PGOOD
FB
R2
SS
C
SS
GND
R1
C
FF
C
OUT
VIN
BOOT
C
BOOT
L
V
OUT
Copyright © 2015 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation
DS6232A/B-01
June 2015
www.richtek.com
1
RT6232A/B
Pin Configurations
(TOP VIEW)
BOOT
GND
LX
VIN
1
2
3
4
8
7
6
5
9
SS
PGOOD
EN
FB
WDFN-8L 2x3
Functional Pin Description
Pin No.
1
Pin Name
BOOT
Pin Function
Bootstrap Supply for High-Side Gate Driver. Connect a 100nF or greater
capacitor from LX to BOOT to power the high-side switch.
System Ground. Provides the ground return path for the control circuitry and
low-side power MOSFET.
Switch Node. LX is the switching node that supplies power to the output and
connect the output LC filter from LX to the output load.
Power Input. Supplies the power switches of the device.
Feedback Voltage Input. This pin is used to set the desired output voltage via
an external resistive divider. The feedback voltage is 0.8V typically.
Enable Control Input. Floating this pin or connecting this pin to GND can disable
the device and connecting this pin to logic high can enable the device.
Power Good Indicator Output. This pin is an open-drain logic output that is
pulled to ground when the output voltage is lower or higher than its specified
threshold under the conditions of OVP, OTP, dropout, EN shutdown, or during
slow start.
Soft-Start Control Input. Connect a capacitor from SS to GND to set the soft-
start period.
2,
GND
9 (Exposed Pad)
3
4
5
6
LX
VIN
FB
EN
7
PGOOD
8
SS
Function Block Diagram
BOOT
VIN
PVCC
Reg
VCC
UV &OV
VREF Protection
OC
Ripple
Gen.
PVCC
UGATE
VCC
1µA
SS
FB
On-Time
Control
Driver
LGATE
LX
FB
EN
0.9V
REF
+
-
GND
VIN
VIBIAS
LX
+
GND
PGOOD
Comparator
- -
Comparator
EN
Copyright © 2015 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation
www.richtek.com
2
DS6232A/B-01
June 2015
RT6232A/B
Operation
The RT6232A/B is a synchronous step-down converter
with advanced constant on-time control mode. Using
the ACOT
TM
control mode can reduce the output
capacitance and provide fast transient response. It can
minimize the component size without additional external
compensation network.
Current Protection
The inductor current is monitored via the internal
switches cycle-by-cycle. Once the output voltage drops
under UV threshold, the RT6232A/B will enter hiccup
mode.
UVLO Protection
To protect the chip from operating at insufficient supply
voltage, the UVLO is needed. When the input voltage of
VIN is lower than the UVLO falling threshold voltage, the
device will be lockout.
Thermal Shutdown
When the junction
threshold value, the
operation. Once the
and is lower than
temperature exceeds the OTP
IC will shut down the switching
junction temperature cools down
the OTP lower threshold, the
converter will autocratically resume switching.
Copyright © 2015 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation
DS6232A/B-01
June 2015
www.richtek.com
3
RT6232A/B
Absolute Maximum Ratings
(Note 1)
Supply Input Voltage ---------------------------------------------------------------------------------
0.3V
to 20V
Switch Node Voltage, LX ----------------------------------------------------------------------------
0.3V
to (V
IN
+ 0.3V)
BOOT Pin Voltage ------------------------------------------------------------------------------------
(V
LX
– 0.3V) to (V
IN
+ 6.3V)
Other Pins -----------------------------------------------------------------------------------------------
0.3V
to 6V
Power Dissipation, P
D
@ T
A
= 25C
WDFN-8L 2x3 ------------------------------------------------------------------------------------------
1.667W
Package Thermal Resistance
(Note 2)
WDFN-8L 2x3,
JA
------------------------------------------------------------------------------------
60C/W
WDFN-8L 2x3,
JC
------------------------------------------------------------------------------------
8C/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 ---------------------------------------------------------------------------------
4.5V
to 18V
Ambient Temperature Range-----------------------------------------------------------------------
40C
to 85C
Junction Temperature Range ----------------------------------------------------------------------
40C
to 125C
Electrical Characteristics
(V
IN
= 12V, T
A
= 25C, unless otherwise specified)
Parameter
Supply Voltage
VIN Supply Input Operating
Voltage
Under-Voltage Lockout
Threshold
Under-Voltage Lockout
Threshold Hysteresis
Shutdown Current
Quiescent Current
Soft-Start
Soft-Start Charge Current
Enable Voltage
EN Voltage Threshold
Symbol
Test Conditions
Min
Typ
Max
Unit
V
IN
V
UVLO
V
UVLO
I
SHDN
I
Q
V
EN
= 0V
V
EN
= 2V, V
FB
= 0.85V
4.5
3.6
--
--
--
--
3.9
340
--
0.5
18
V
4.2
--
5
--
mV
µA
mA
A
I
SS
--
1
--
V
EN
Rising
V
EN
Falling
1.3
1.08
1.5
1.28
1.7
1.48
V
Copyright © 2015 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation
www.richtek.com
4
DS6232A/B-01
June 2015
RT6232A/B
Parameter
Feedback Voltage
Feedback Voltage Threshold
Internal MOSFET
High-Side On-Resistance
Low-Side On-Resistance
Current Limit
High-Side Switch Current Limit
Low-Side Switch Valley
Current Limit
Switching Frequency
Switching Frequency
On-Time Timer Control
Maximum Duty Cycle
Minimum On Time
Minimum Off Time
Power Good
PGOOD Threshold
V
PGOOD
FB Rising
FB Falling
--
--
90
85
--
--
%
D
MAX
t
ON(MIN)
t
OFF(MIN)
--
--
--
86
60
240
--
--
--
%
nS
f
OSC
400
500
--
kHz
I
LIM_H
I
LIM_L
--
2.6
5.8
3.3
--
A
--
R
DS(ON)_H
R
DS(ON)_L
V
BOOT
− V
LX
= 4.8V
--
--
210
120
--
--
mΩ
V
FB_TH
4.5V ≤ V
IN
≤ 18V
0.788
0.8
0.812
V
Symbol
Test Conditions
Min
Typ
Max
Unit
Output Under Voltage And Over Voltage Protections
OVP Trip Threshold
OVP Propagation Delay
UVP Trip Threshold
UVP Propagation Delay
Thermal Shutdown
Thermal Shutdown Threshold
Thermal Shutdown Hysteresis
T
SD
T
SD
--
--
150
20
--
--
°C
UVP Detect
Hysteresis
OVP Detect
--
--
45
--
--
125
10
50
10
5
--
--
55
--
--
%
µS
%
µS
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 © 2015 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation
DS6232A/B-01
June 2015
www.richtek.com
5
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