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RT7247CHGSP Evaluation Board

EVB_RT7247CHGSP

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The RT7247C 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 RT7247C'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 RT7247C 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 RT7247C is available in an SOP-8 (Exposed Pad) package.

Purpose

The RT7247C 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 RT7247C evaluation board (EVB) and provides information to enable operation and modification of the evaluation board and circuit to suit individual requirements.

Introduction

General Product Information

The RT7247C 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 RT7247C'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 RT7247C 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 RT7247C is available in an SOP-8 (Exposed Pad) package.

Product Feature

  • ±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 : 800kHz
  • Output Adjustable from 0.8V to 12V
  • 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

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

RT7247CHGSP, PSOP-8 (Exposed Pad)

Operation Frequency

Steady 800kHz 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

 

Bench Test Setup Conditions

Headers Description and Placement

Technical Document Image Preview

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 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

SS

Soft-start control test point

Soft start waveform

GND

Ground

Ground

 

Power-up & Measurement Procedure

1.Apply a 12V nominal input power supply (4.5V < VIN < 18V) 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 (>2.0V) 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.

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:

Technical Document Image Preview

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 RT7247C IC datasheet.

Schematic, Bill of Materials and Board Layout

EVB Schematic Diagram

Technical Document Image Preview

C1, C2: 10μF/50V/X5R, 1206, TDK C3216X5R1H106K

C4, C5: 22μF/16V/X5R, 1210, Murata GRM32ER61C226K

L1: 6.8μH TAIYO YUDEN NR8040T6R8N, DCR=25mΩ

Bill of Materials

Reference

Qty

Part number

Description

Package

Manufacture

U1

1

RT7247CHGSP

DC-DC Converter

PSOP-8

Richtek

C1, C2

2

C3216X5R1H106K160AB

10uF/±10%/50V/X5R

Ceramic Capacitor

1206

TDK

C4, C5

2

GRM32ER61C226KE20#

22uF/±10%/16V/X5R

Ceramic Capacitor

1210

Murata

C7

1

0603B332K500

3.3nF/±10%/50V/X7R

Ceramic Capacitor

0603

WALSIN

C3, C6, C10,C11

4

C1608X7R1H104K080AA

0.1uF/±10%/50V/X7R

Ceramic Capacitor

0603

TDK

C8,C9,C12,C13

0

Not Installed

0603

L1

1

NR8040T6R8N

6.8uH/4.0A/±30%, DCR=25mΩ, Inductor

8mmx8mmx4mm

TAIYO YUDEN

R1

1

75kΩ/±1%, Resistor

0603

R2

1

24kΩ/±1%, Resistor

0603

R3

1

17kΩ/±1%, Resistor

0603

R4

1

100kΩ/±1%, Resistor

0603

R5

0

Not Installed

0603

D1, D2

0

Not Installed

TP

4

Test Pin

GP

4

Golden Pin

 

EVB Layout

Technical Document Image Preview

Top View (1stlayer)

Technical Document Image Preview

Bottom View (2nd Layer)

Technical Document Image Preview

Component Placement Guide—Component Side (1stlayer)

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PCB Layout—Component Side (1stLayer)

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Component Placement Guide—Bottom Side (2ndlayer)

Technical Document Image Preview

PCB Layout—Bottom Side (2ndlayer)


Title Last Update Share Download
Evaluation Board User Guide 2015/06/01
Bill of Materials 2015/06/01
Gerber File 2015/09/24
Schematic 2015/09/30
RT7247C

2A, 18V, 800kHz Synchronous Step-Down Converter

RT7247C

The RT7247C 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 RT7247C's current mode architecture and external compensation allow the transient response to be optimized over a wide input range and loads. Cycle-by-cycle current limit provides protection against shorted outputs, and soft-start eliminates input current surge during start-up. The RT7247C also provides 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 RT7247C is available in an SOP-8 (Exposed Pad) package.

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