Step-Down Converter. RT6238A Datasheet

RT6238A Converter. Datasheet pdf. Equivalent

RT6238A Datasheet
Recommendation RT6238A Datasheet
Part RT6238A
Description Synchronous Step-Down Converter
Feature RT6238A; ® RT6238A/B 8A, 18V, 500kHz, ACOTTM Synchronous Step-Down Converter General Description The RT6238.
Manufacture Richtek
Datasheet
Download RT6238A Datasheet




Richtek RT6238A
®
RT6238A/B
8A, 18V, 500kHz, ACOTTM Synchronous Step-Down Converter
General Description
The RT6238A/B is a high-performance 500kHz, 8A step-
down regulator with internal power switches and
synchronous rectifiers. It features quick transient response
using its Advanced Constant On-Time (ACOTTM) control
architecture that provides stable operation with small
ceramic output capacitors and without complicated
external compensation, among other benefits. The input
voltage range is from 4.5V to 18V and the output is
adjustable from 0.7V to 8V. The proprietary ACOTTM control
improves upon other fast response constant on-time
architectures, achieving nearly constant switching
frequency over line, load, and output voltage ranges. Since
there is no internal clock, response to transients is nearly
instantaneous and inductor current can ramp quickly to
maintain output regulation without large bulk output
capacitance. The RT6238A/B is stable with and optimized
for ceramic output capacitors. With internal 35mΩ switches
and 14mΩ synchronous rectifiers, the RT6238A/B displays
excellent efficiency and good behavior across a range of
applications, especially for low output voltages and low
duty cycles. Cycle-by-cycle current limit provides
protection against shorted outputs, input under-voltage
lockout, externally-adjustable soft-start, output under- and
over-voltage protection, and thermal shutdown provide safe
and smooth operation in all operating conditions. The
RT6238A/B is available in the UQFN-14L 2x3 (FC)
package, with exposed thermal pad.
Features
Fast Transient Response
Advanced Constant On-Time (ACOTTM) Control
4.5V to 18V Input Voltage Range
Adjustable Output Voltage from 0.7V to 8V
8A Output Current
35mΩ Internal High-Side N-MOSFET and 14mΩ
Internal Low-Side N-MOSFET
Steady 500kHz Switching Frequency
Up to 95% Efficiency
Optimized for All Ceramic Capacitors
Externally-Adjustable, Pre-Biased Compatible Soft-
Start
Cycle-by-Cycle Current Limit
Input Under-Voltage Lockout
Output Over- and Under-Voltage Protection
Power Good Output
Thermal Shutdown
Applications
Industrial and Commercial Low Power Systems
Computer Peripherals
LCD Monitors and TVs
Green Electronics/Appliances
Point of Load Regulation for High-Performance DSPs,
FPGAs, and ASICs
Simplified Application Circuit
VIN
EN Signal
Power Good
RT6238A/B
VIN SW
BOOT
EN FB
PGOOD
PVCC
SS
GND
VOUT
Copyright ©2017 Richtek Technology Corporation. All rights reserved.
DS6238A/B-07 March 2017
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
1



Richtek RT6238A
RT6238A/B
Ordering Information
RT6238A/B
Package Type
QUF : UQFN-14L 2x3 (U-Type) (FC)
Lead Plating System
G : Green (Halogen Free and Pb Free)
UVP Option
H : Hiccup Mode UVP
L : Latched OVP & UVP
Note :
A : PSM
B : PWM
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.
Marking Information
RT6238ALGQUF
0K : Product Code
0KW
W : Date Code
RT6238BLGQUF
0H : Product Code
0HW
W : Date Code
RT6238AHGQUF
0L : Product Code
0LW
W : Date Code
Pin Configurations
(TOP VIEW)
RT6238BHGQUF
0J : Product Code
0JW
W : Date Code
14 13 12
AGND 1
11 GND
FB 2
10 GND
PVCC 3
9 GND
PGOOD 4
8 VIN
56 7
UQFN-14L 2x3 (FC)
Copyright ©2017 Richtek Technology Corporation. All rights reserved.
www.richtek.com
2
is a registered trademark of Richtek Technology Corporation.
DS6238A/B-07 March 2017



Richtek RT6238A
RT6238A/B
Functional Pin Description
Pin No.
1
Pin Name
AGND
Analog GND.
Pin Function
2 FB
Feedback Voltage Input. It is used to regulate the output of the converter to a set
value via an external resistive voltage divider. The feedback reference voltage is
0.7V typically.
3
PVCC
Internal Regulator Output. Connect a 1F capacitor to GND to stabilize output
voltage.
4
PGOOD
Power Good Indicator Open-Drain Output.
Bootstrap Supply for High-Side Gate Driver. This capacitor is needed to drive the
5
BOOT
power switch's gate above the supply voltage. It is connected between the SW and
BOOT pins to form a floating supply across the power switch driver. A 0.1F
capacitor is recommended for use.
6 SW
Switch Node. Connect this pin to an external L-C filter.
7, 8 VIN
9, 10, 11, 12 GND
Power Input. The input voltage range is from 4.5V to 18V. Must bypass with a
suitably large (10F x 2) ceramic capacitor.
Ground.
13 EN
Enable Control Input. A logic-high enables the converter; a logic-low forces the IC
into shutdown mode reducing the supply current to less than 10A.
14 SS
Soft-Start Time Setting. An external capacitor should be connected between this
pin and GND.
Function Block Diagram
PVCC
BOOT
VIN
PVCC
Reg Min.
VIBIAS
VREF
Off PVCC
UGATE
VIN
OC
Control
Driver
LGATE
UV & OV
GND SW
PVCC
SW
Ripple
Gen.
6µA
SS
+
+
FB -
Comparator
0.9 VREF
FB
+
-
VIN Comparator
SW
GND
PGOOD
SW On-Time
EN
EN
Copyright ©2017 Richtek Technology Corporation. All rights reserved.
DS6238A/B-07 March 2017
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
3







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