EVB RT7250BZSP-00

RT7250BZSP
Evaluation Board
your power partner.
RT7250BZSP Evaluation Board
Purpose
The RT7250B 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 4V to 17V. This document explains the function and use of the RT7250B
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
KEY PERFORMANCE SUMMARY TABLE ................................................................................................................................... 2
BENCH TEST SETUP CONDITIONS............................................................................................................................................ 3
SCHEMATIC, BILL OF MATERIALS & BOARD LAYOUT ............................................................................................................... 5
MORE INFORMATION..........................................................................................................................錯誤! 尚未定義書籤。
IMPORTANT NOTICE FOR RICHTEK REFERENCE DESIGNS .....................................................................錯誤! 尚未定義書籤。
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RT7250BZSP
Evaluation Board
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Introduction
General Product Information
The RT7250B is a high efficiency, monolithic synchronous step-down DC/DC converter that operates at 800kHz and
delivers up to 2A output current from a 4V to 17V input supply. The RT7250B’s current mode architecture allows the
transient response to be optimized. 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 voltage protection, and thermal shutdown. The low current (<5μA) shutdown mode provides output
disconnect, enabling easy power management in battery-powered systems. The RT7250B is available in a SOP-8
(Exposed Pad) package.
Product Feature

4V to 17V Input Voltage Range


2A Output Current
Internal N-MOSFETs
Current Mode Control
Fixed Frequency Operation : 800kHz
Output Adjustable from 0.8V to 12V
Up to 95% Efficiency
Internal Compensation
Stable with Low ESR Ceramic Output Capacitors
Cycle-by-Cycle Over Current Protection
Input Under Voltage Lockout
Output Under Voltage Protection
Output Over Voltage Protection
Power Good Indicator
Thermal Shutdown Protection

RoHS Compliant and Halogen Free


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Key Performance Summary Table
Key Features
Evaluation Board Number: PCB009_V1
Default Input Voltage
12V
Max Output Current
2A
Default Output Voltage
3.3V
Default Marking & Package Type
RT7250BZSP (SOP-8 (Exposed Pad))
Operation Frequency
Steady 800kHz at all load currents
Other Key Features
4V to 17V Input Voltage Range
Power Good Indicator
Protection
Over Current Protection
Hiccup Mode Output Under-Voltage & Over-Voltage Protection
Thermal Shutdown
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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
[email protected]
Test Points
The EVB is provided with the test points and pin names listed in the table below.
Test point/
Signal
Comment (expected waveforms or voltage levels on test points)
VIN
Input voltage
Input voltage range= 4V to 17V
VOUT
Output voltage
Default output voltage = 3.3V
Pin name
Output voltage range= 0.8V to 12V
(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
PG
Power Good test point
Power Good Indicator
V1
External Voltage for PG
External voltage terminal for PG pull-up voltage.
GND
Ground
Ground
Power-up & Measurement Procedure
1.
Apply a 12V nominal input power supply (4V < VIN < 17V) to the VIN and GND terminals.
2.
The EN voltage is pulled to logic high by R4 (100kΩ to VIN) to enable operation. Drive EN high (>2.5V) to
enable operation or low (<0.4V) to disable operation.
3.
Verify the output voltage (approximately 3.3V) between VOUT and GND.
4.
Connect an external load up to 2A to the VOUT and GND terminals and verify the output voltage and current.
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Output Voltage Setting
Set the output voltage with the resistive divider (R1, R2) between VOUT and GND with the midpoint connected to
FB. The output is set by the following formula:
VOUT = 0.8 x (1 +
R1
)
R2
The installed VOUT capacitors (C4, C5) are 22μF, 16V X5R ceramic types. Do not exceed their operating voltage
range and consider their voltage coefficient (capacitance vs. bias voltage) and ensure that the capacitance is
sufficient to maintain stability and provide sufficient transient response for your application. This can be verified by
checking the output transient response as described in the RT7250 IC datasheet.
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Schematic, Bill of Materials & Board Layout
EVB Schematic Diagram
C1, C2: 10μF/50V/X5R, 1206, TDK C3216X5R1H106K
C4, C5: 22μF/16V/X5R, 1210, Murata GRM32ER61C226K
L1: 6.8μH TAIYO YUDEN NR8040T6R8N, DCR=25mΩ
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Bill of Materials
Reference
Qty
Part number
Description
U1
1
RT7250BZSP
DC-DC Converter
Package
Manufacture
SOP-8
Richtek
(Exposed Pad)
C1, C2
2
C3216X5R1H106K160AB
10μF/±10%/50V/X5R
1206
TDK
1210
Murata
0603
Murata
0603
TDK
Ceramic Capacitor
C4, C5
2
GRM32ER61C226KE20#
22μF/±10%/16V/X5R
Ceramic Capacitor
10nF/±10%/50V/X7R
C7
1
GRM32MR71H103KA01#
Ceramic Capacitor
C3, C6
2
C1608X7R1H104K080AA
0.1μF/±10%/50V/X7R
Ceramic Capacitor
C8, C9,
0
Not Installed
0603
C10
1
R1
1
47kΩ/±1%, Resistor
0603
R2
1
15kΩ/±1%, Resistor
0603
R3, R4
1
100kΩ/±1%, Resistor
0603
CP1
1
Short
D3, R6
0
Not Installed
TP
4
Test Pin
GP
6
Golden Pin
UG7250BZSP-00
NR8040T6R8N
6.8μH/3.7A/±30%,
L1
January 2015
DCR=25mΩ, Inductor
6
8mmx8mmx4mm
TAIYO YUDEN
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EVB Layout
st
Top View (1 layer)
Bottom View (4th Layer)
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st
Component Placement Guide—Component Side (1 layer)
st
PCB Layout—Component Side (1 Layer)
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th
PCB Layout—Bottom Side (4 Layer)
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More Information
For more information, please find the related datasheet or application notes from Richtek website
http://www.richtek.com.
Important Notice for Richtek Evaluation Board
THIS DOCUMENT IS FOR REFERENCE ONLY, NOTHING CONTAINED IN THIS DOCUMENT SHALL BE CONSTRUED AS RICHTEK’S WARRANTY, EXPRESS
OR IMPLIED, UNDER CONTRACT, TORT OR STATUTORY, WITH RESPECT TO THE PRESENTATION HEREIN. IN NO EVENT SHALL RICHTEK BE LIABLE TO
BUYER OR USER FOR ANY AND ALL DAMAGES INCLUDING WITHOUT LIMITATION TO DIRECT, INDIRECT, SPECIAL, PUNITIVE OR CONSEQUENTIAL
DAMAGES.
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