RT8237J PWM Controller Datasheet

RT8237J Datasheet, PDF, Equivalent


Part Number

RT8237J

Description

High Efficiency Single Synchronous Buck PWM Controller

Manufacture

RICHTEK

Total Page 19 Pages
Datasheet
Download RT8237J Datasheet


RT8237J
®
RT8237J
High Efficiency Single Synchronous Buck PWM Controller
General Description
The RT8237J PWM controller provides high efficiency,
excellent transient response, and high DC output accuracy
needed for stepping down high voltage batteries to
generate low voltage CPU core, I/O, and chipset RAM
supplies in notebook computers.
The constant on-time PWM control scheme handles wide
input/output voltage ratios with ease and provides 100ns
instant-onresponse to load transients while maintaining
a relatively constant switching frequency.
The RT8237J achieves high efficiency at a reduced cost
by eliminating the current sense resistor found in
traditional current mode PWMs. Efficiency is further
enhanced by its ability to drive very large synchronous
rectifier MOSFETs and enter diode emulation mode at
light load condition. The Buck conversion allows this device
to directly step down high voltage batteries at the highest
possible efficiency. The pre-set frequency selections
minimize design effort required for new designs. The
RT8237J is intended for CPU core, chipset, DRAM, or
other low voltage supplies as low as 0.7V. The RT8237J
is available in the WDFN-10L 3x3 package.
Features
Wide Input Voltage Range : 4.5V to 26V
Output Voltage Range : 0.7V to 3.3V
Built-In 0.5% 0.7V Reference Voltage
Quick Load-Step Response within 100ns
4700ppm/°C Current Source for Current Limit
RDS(ON)
Adjustable Current Limit with Low-Side MOSFET
4 Selectable Frequency Setting
Soft-Start Control
Drives Large Synchronous-Rectifier FETs
Integrated Boot Switch
Built-In OVP/OCP/UVP
Thermal Shutdown
Power Good Indicator
RoHS Compliant and Halogen Free
Applications
Notebook Computers
CPU Core Supply
Chipset/RAM Supply as Low as 0.7V
Generic DC-DC Power Regulator
Simplified Application Circuit
RT8237J
VCC
VCC
BOOT
PGOOD
EN
RF
CS
UGATE
PHASE
LGATE
GND
FB
VIN
VOUT
Copyright ©2018 Richtek Technology Corporation. All rights reserved.
DS8237J-00 August 2018
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
1

RT8237J
RT8237J
Ordering Information
RT8237J
Pin 1 Orientation***
(2) : Quadrant 2, Follow EIA-481-D
Package Type
QW : WDFN-10L 3x3 (W-Type)
Lead Plating System
G : Green (Halogen Free and Pb Free)
Note :
***Empty means Pin1 orientation is Quadrant 1
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.
Pin Configuration
(TOP VIEW)
PGOOD 1
CS 2
EN 3
FB 4
RF 5
10 BOOT
9 UGATE
8 PHASE
7 VCC
11 6 LGATE
WDFN-10L 3x3
Marking Information
88 : Product Code
88 YM
DNN
YMDNN : Date Code
Functional Pin Description
Pin No.
Pin Name
Pin Function
1
PGOOD
Open drain power good indicator. High impedance indicates power is good.
2 CS
Current limit threshold setting input. Connect a setting resistor to GND and the
current limit threshold is equal to 1/8 of the voltage at this pin.
3 EN
Enable control input. Pull low to GND to disable the PWM.
4 FB
VOUT feedback input. Connect FB to a resistor voltage divider from VOUT to GND
to adjust the output from 0.7V to 3.3V
5 RF
Switching frequency selection. Connect a resistance to select switching frequency
as shown in Electrical Characteristics. The switching frequency is detected and
latched after startup. This pin also controls diode emulation mode or forced CCM
selection.
Pull down to GND with resistor: Diode Emulation Mode.
Connect to PGOOD with resistor : forced CCM after PGOOD becomes high.
6
LGATE
Gate drive output for low-side external MOSFET.
7 VCC
Supply voltage input. This pin provides the power for the buck controller, the
low-side driver and the bootstrap circuit for high-side driver. Bypass to GND with a
1F ceramic capacitor.
External inductor connection pin for PWM converter. It behaves as the current
8
PHASE
sense comparator input for low-side MOSFET RDS(ON) sensing and reference
voltage for on time generation.
9
UGATE
Gate drive output for high-side external MOSFET.
10
BOOT
Bootstrap supply for high-side gate driver. Connect through a capacitor to the
floating node (PHASE).
11
(Exposed Pad)
GND
Ground. The exposed pad must be soldered to a large PCB and connected to
GND for maximum power dissipation.
Copyright ©2018 Richtek Technology Corporation. All rights reserved.
www.richtek.com
2
is a registered trademark of Richtek Technology Corporation.
DS8237J-00 August 2018


Features ® RT8237J High Efficiency Single Synch ronous Buck PWM Controller General Des cription The RT8237J PWM controller pro vides high efficiency, excellent transi ent response, and high DC output accura cy needed for stepping down high voltag e batteries to generate low voltage CPU core, I/O, and chipset RAM supplies in notebook computers. The constant on-ti me PWM control scheme handles wide inpu t/output voltage ratios with ease and p rovides 100ns “instant-on” response to load transients while maintaining a relatively constant switching frequenc y. The RT8237J achieves high efficiency at a reduced cost by eliminating the c urrent sense resistor found in traditio nal current mode PWMs. Efficiency is fu rther enhanced by its ability to drive very large synchronous rectifier MOSFET s and enter diode emulation mode at lig ht load condition. The Buck conversion allows this device to directly step dow n high voltage batteries at the highest possible efficiency. The pre-set frequency selections minimize desi.
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