Richtek RT7247AHGSP User Manual
RT7247AHGSP
Evaluation Board
UG7247AHGSP-00 July 2014
www.richtek.com
Purpose
The RT7247A is a high-efficiency current mode synchronous step-down regulator that can deliver up to 2A output
current from a wide input voltage range of 4.5V to 18V. This document explains the function and use of the
RT7247A evaluation board (EVB) and provides information to enable operation and modification of the evaluation
board and circuit to suit individual requirements.
Table of Contents
Purpose .......................................................................................................................................................... 1
Introduction ..................................................................................................................................................... 2
General Product Information ...................................................................................................................... 2
Key Performance Summary Table ............................................................................................................. 3
Bench Test Setup Conditions ......................................................................................................................... 4
Headers Description and Placement ......................................................................................................... 4
Test Points ................................................................................................................................................. 4
Power-up & Measurement Procedure ........................................................................................................ 5
Output Voltage Setting ............................................................................................................................... 5
Schematic, Bill of Materials and Board Layout .............................................................................................. 6
EVB Schematic Diagram ............................................................................................................................ 6
Bill of Materials ........................................................................................................................................... 7
EVB Layout ................................................................................................................................................ 8
More Information .......................................................................................................................................... 11
Important Notice for Richtek Evaluation Board ............................................................................................ 11
RT7247AHGSP
Evaluation Board
UG7247AHGSP-00 July 2014 www.richtek.com
2
Introduction
General Product Information
General Description
The RT7247A 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 RT7247A's current mode architecture and external
compensation allow the transient response to be optimized over a wide range of loads and output capacitors.
Cycle-by-cycle current limit provides protection against shorted outputs and soft-start eliminates input current surge
during start-up. The RT7247A also provides output under voltage protection and thermal shutdown protection. The
low current (<3μA) shutdown mode provides output disconnection, enabling easy power management in
battery-powered systems. The RT7247A is available in an SOP-8 (Exposed Pad) package.
Features
±1.5% High Accuracy Feedback Voltage
4.5V to 18V Input Voltage Range
2A Output Current
Integrated N-MOSFET Switches
Current Mode Control
Fixed Frequency Operation : 340kHz
Output Adjustable from 0.8V to 15V
Up to 95% Efficiency
Programmable Soft-Start
Stable with Low-ESR Ceramic Output Capacitors
Cycle-by-Cycle Over Current Protection
Input Under Voltage Lockout
Output Under Voltage Protection
Thermal Shutdown Protection
RT7247AHGSP
Evaluation Board
UG7247AHGSP-00 July 2014 www.richtek.com
3
Key Performance Summary Table
Key features
Evaluation board number: PCB004_V1
Default Input Voltage
12V
Max Output Current
2A
Default Output Voltage
3.3V
Default Marking & Package Type
RT7247AHGSP, PSOP-8 (Exposed Pad)
Operation Frequency
Steady 340kHz at all loads
Other Key Features
4.5V to 18V Input Voltage Range
Programmable Soft-Start
Protection
Output Under-Voltage Protection (hiccup mode):
Cycle-by-cycle Current Limit
Thermal Shutdown
RT7247AHGSP
Evaluation Board
UG7247AHGSP-00 July 2014 www.richtek.com
4
Bench Test Setup Conditions
Headers Description and Placement
Please carefully inspect the EVB IC and external components, comparing them to the
following Bill of Materials, to ensure that all components are installed and undamaged. If any
components are missing or damaged during transportation, please contact the distributor or
send e-mail to evb_service@richtek.com.
Test Points
The EVB is provided with the test points and pin names listed in the table below.
Test point/
Pin name
Signal
Comment (expected waveforms or voltage levels on test
points)
VIN
Input voltage
Input voltage range= 4.5V to 18V
VOUT
Output voltage
Default output voltage = 3.3V
Output voltage range= 0.8V to 15V
(see ‘’ Output Voltage Setting’’ section for changing output voltage
level)
SW
Switching node test point
SW waveform
EN
Enable test point
Enable signal. EN is automatically pulled high (by R4) to enable
operation. Connect EN low to disable operation.
BS
Boot strap supply test point
Floating supply voltage for the high-side N-MOSFET switch
SS
Soft-start control test point
Soft start waveform
GND
Ground
Ground
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