RT7285 SynchronousStep-Down Converter Datasheet

RT7285 Datasheet, PDF, Equivalent


Part Number

RT7285

Description

SynchronousStep-Down Converter

Manufacture

Richtek

Total Page 15 Pages
Datasheet
Download RT7285 Datasheet


RT7285
®
RT7285/A
1.5A, 18V, 500kHz ACOTTMSynchronous Step-Down Converter
General Description
The RT7285/A is a synchronous step-down converter with
Advanced Constant On-Time (ACOTTM) mode control. The
ACOTTM provides a very fast transient response with few
external components. The low impedance internal
MOSFET supports high efficiency operation with wide input
voltage range from 4.3V to 18V. The proprietary circuit of
the RT7285/A enables to support all ceramic capacitors.
The output voltage can be adjusted between 0.6V and 8V.
Ordering Information
RT7285/A
Package Type
E : SOT-23-6
J6 : TSOT-23-6
Lead Plating System
G : Green (Halogen Free and Pb Free)
TSOT-23-6
SOT-23-6
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.
Pin Configurations
(TOP VIEW)
SW VIN EN
654
23
BOOT GND FB
T/SOT-23-6
Features
4.3V to 18V Input Voltage Range
1.5A Output Current
Advanced Constant On-Time Control
Fast Transient Response
Support All Ceramic Capacitors
Up to 95% Efficiency
500kHz Switching Frequency
Adjustable Output Voltage from 0.6V to 8V
Cycle-by-Cycle Current Limit
Input Under-Voltage Lockout
Hiccup Mode Under-Voltage Protection
Thermal Shutdown
Power Saving Mode for High Efficiency at Light
Load
RoHS Compliant and Halogen Free
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
Marking Information
RT7285GE
0M=DNN
0M= : Product Code
DNN : Date Code
RT7285AGJ6
0D=DNN
0D= : Product Code
DNN : Date Code
Simplified Application Circuit
RT7285/A
VIN VIN BOOT
SW
Enable
EN
GND
FB
VOUT
Copyright ©2014 Richtek Technology Corporation. All rights reserved.
DS7285/A-01 October 2014
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
1

RT7285
RT7285/A
Functional Pin Description
Pin No.
Pin Name
Pin Function
1
BOOT
Bootstrap Supply for High-Side Gate Driver. Connect a 0.1F ceramic capacitor
between the BOOT and SW pins.
2 GND Power Ground.
3 FB
4 EN
Feedback Voltage Input. The pin is used to set the output voltage of the converter
via a resistive divider. The converter regulates VFB to 0.6V
Enable Control Input. Connect EN to a logic-high voltage to enable the IC or to a
logic-low voltage to disable. Do not leave this high impedance input unconnected.
5 VIN
Power Input. The input voltage range is from 4.3V to 18V. Must bypass with a
suitable large ceramic capacitor at this pin.
6 SW
Switch Node. Connect to external L-C filter.
Function Block Diagram
BOOT VIN
VIN
Reg
VIBIAS
PVCC
VREF
Min off
PVCC
OC
UV & OV
PVCC
SW
Ripple
Gen.
+--
Comparator
Control
Driver
GND SW
VIN
EN On-Time
UGATE
LGATE
SW
SW
GND
FB EN
Operation
The RT7285/A is a synchronous step-down converter with
advanced constant on-time control mode. Using the ACOT
control mode can reduce the output capacitance and 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 RT7285/A will enter hiccup mode.
Copyright ©2014 Richtek Technology Corporation. All rights reserved.
www.richtek.com
2
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 temperature exceeds the OTP
threshold value, the IC will shut down the switching
operation. Once the junction temperature cools down and
is lower than the OTP lower threshold, the converter will
autocratically resume switching.
is a registered trademark of Richtek Technology Corporation.
DS7285/A-01 October 2014


Features ® RT7285/A 1.5A, 18V, 500kHz ACOTTMSyn chronous Step-Down Converter General D escription The RT7285/A is a synchronou s step-down converter with Advanced Con stant On-Time (ACOTTM) mode control. Th e ACOTTM provides a very fast transient response with few external components. The low impedance internal MOSFET supp orts high efficiency operation with wid e input voltage range from 4.3V to 18V. The proprietary circuit of the RT7285/ A enables to support all ceramic capaci tors. The output voltage can be adjuste d between 0.6V and 8V. Ordering Informa tion RT7285/A Package Type E : SOT-23-6 J6 : TSOT-23-6 Lead Plating System G : Green (Halogen Free and Pb Free) TSOT- 23-6 SOT-23-6 Note : Richtek products a re :  RoHS compliant and compatible with the current requirements of IPC/JE DEC J-STD-020.  Suitable for use in SnPb or Pb-free soldering processes. Pi n Configurations (TOP VIEW) SW VIN EN 6 54 23 BOOT GND FB T/SOT-23-6 Features  4.3V to 18V Input Voltage Range  1.5A Output Current  Advanced C.
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