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RT7243GQW Evaluation Board

EVB_RT7243GQW

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The RT7243 is a high efficiency, monolithic synchronous step-down DC/DC converter that can deliver up to 6A output current from a 4.5V to 18V input supply. The RT7243 current-mode architecture with external compensation allows 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 startup. Fault condition protections include output under-voltage protection, output over-voltage protection, and over temperature protection. The low current shutdown mode provides output disconnection, enabling easy power management in battery-powered systems. The RT7243 is available in WQFN-14AL 3.5x3.5 package.

Purpose

The RT7243 is a synchronous step-down converter with current mode control, which can deliver up to 6A output current from a wide input voltage range of 4.5V to 18V. This document explains the function and use of the RT7243 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 RT7243 is a high efficiency, monolithic synchronous step-down DC/DC converter that can deliver up to 6A output current from a 4.5V to 18V input supply. The RT7243 current-mode architecture with external compensation allows 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 startup. Fault condition protections include output under-voltage protection, output over-voltage protection, and over temperature protection. The low current shutdown mode provides output disconnection, enabling easy power management in battery-powered systems. The RT7243 is available in WQFN-14AL 3.5x3.5 package.

Product Feature

  • Low RDS(ON) Power MOSFET Switches 26mΩ/19mΩ    
  • Input Voltage Range : 4.5V to 18V
  • Adjustable Switching Frequency : 200kHz to 1.6MHz
  • Current-Mode Control
  • Synchronous to External Clock : 200kHz to 1.6MHz
  • Accurate Voltage Reference : 0.8V ± 1.25%
  • Monotonic Start-Up into Pre-biased Outputs
  • Adjustable Soft-Start
  • Power Good Indicator
  • Under-Voltage and Over-Voltage Protection
  • Input Under-Voltage Lockout
  • RoHS Compliant and Halogen Free

Key Performance Summary Table

Key Features

Evaluation Board Number: PCB006_V1

Default Input Voltage

12V

Max Output Current

6A

Default Output Voltage

1.0V

Default Marking & Package Type

RT7243GQW, WQFN-14AL 3.5x3.5

Operation Frequency

Steady 500kHz at all loads

Other Key Features

4.5V to 18V Input Voltage Range

Programmable Soft-Start, Adjustable Switching Frequency

Synchronous to External Clock

Power Good Indicator

Protection

Output Under-Voltage Protection (hiccup mode)

Output Over-Voltage Protection

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, VIN_EXT

Input voltage

Input voltage range= 4.5V to 18V

VOUT

Output voltage

Default output voltage = 1.0V

Output voltage range= 0.8V to 8V

(see ‘’ Output Voltage Setting’’ section for changing output voltage level)

LX

Switching node test point

LX waveform

EN

Enable test point

Enable signal. Floating this EN pin or connecting this pin to pull high enable operation; connecting this pin to GND can disable the device.

SYNC

Ext Frequency Sync Input

External Frequency Synchronization Input. Connecting external clock to this pin changes the switching frequency.

BS

Boot strap supply test point

Floating supply voltage for the high-side N-MOSFET switch

GND

Ground

Ground

SS

Soft-start control test point

Soft start waveform

VCC_EXT

External Voltage for PG

External voltage terminal for PG pull-up voltage.

PG

Power good output test point

Connected to VCC_EXT through RPG1, Power Good Indicator

JP2

VIN & PVIN control

Install jumper to combine or separate VIN and PVIN.

JP1

PG control

VIN voltage terminal for PG pull-up voltage.

J9

Chip enable control

Install jumper or drive EN directly to enable or disable operation

 

Power-up & Measurement Procedure

1.Connect input power (4.5V < VIN < 18V) and input ground to VIN and GND test pins respectively.

2.Connect positive end and negative terminals of load to VOUT and GND test pins respectively.

3.There is a 3-pin header “EN” for enable control. To use a jumper at “H” option to tie EN test pin to input power VIN for enabling the device. Inversely, to use a jumper at “L” option to tie EN test pin and ground GND for disabling the device.

4.The PVIN and VIN pins can be connected together using a jumper across “Combine” by the 3-pin header JP2. Inversely, these two input rails can be separated by using a jumper across “Separate” if desired.

5.The 2-pin header JP1 “VIN-PG” is for PGOOD pin supply, when using a jumper across this header, the PG signal can be supplied by VIN pin Voltage.

6.Verify the output voltage (approximately 1.0V) between VOUT and GND.

7.Connect an external load up to 6A 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 (C5, C6) 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 RT7243 IC datasheet.

Schematic, Bill of Materials & Board Layout

EVB Schematic Diagram

Technical Document Image Preview

C4: 10μF/50V/X5R, 1206, TDK C3216X5R1H106K

C2, C5, C6: 22μF/16V/X5R, 1210, Murata GRM32ER61C226K

L1: 1.4μH TAIYO YUDEN NR8040T1R4N, DCR=7mΩ

Bill of Materials

Reference

Qty

Part number

Description

Package

Manufacture

U1

1

RT7243GQW

DC-DC Converter

WQFN-14AL 3.5x3.5

RICHTEK

C4

1

C3216X5R1H106K160AB

10μF/±10%/50V/X5R

Ceramic Capacitor

1206

TDK

C2, C5, C6

3

GRM32ER61C226KE20#

22μF/±10%/16V/X5R

Ceramic Capacitor

1210

Murata

CSS

1

GRM32MR71H103KA01#

10nF/±10%/50V/X7R

Ceramic Capacitor

0603

Murata

CCOMP1

1

GRM31CR71A822KA01

8.2nF/±10%/50V/X7R

Ceramic Capacitor

0603

Murata

CCOMP2

1

0603B181K500CT

180pF/±10%/50V/X7R

Ceramic Capacitor

0603

WALSIN

C3, C7, CBOOT

3

C1608X7R1H104K080AA

0.1μF/±10%/50V/X7R

Ceramic Capacitor

0603

TDK

C1, CFF, C2F, CEN, REN2, RTR1, RTR2, RPG2, D1

0

Not Installed

0603

L1

1

NR8040T1R4N

1.4μH/9.0A/±30%, DCR=7mΩ, Inductor

8mmx8mmx4mm

TAIYO YUDEN

R1

1

6kΩ/±1%, Resistor

0603

R2

1

24kΩ/±1%, Resistor

0603

RCOMP

1

0.68kΩ/±1%,

0603

RT, REN1, RPG1

3

100kΩ/±1%,

0603

JP1

1

2-Pin Header

JP2, J9

2

3-Pin Header

GP

11

VIN_EXT, BS, SS, TRACK, EN, LX, SYNC, PG, VCC_EXT, VIN, GND

Golden Pin

J3, J4

2

VOUT, GND

Test Pin

 

EVB Layout

Technical Document Image Preview

Top View (1stlayer)

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Bottom View (4th Layer)

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Component Placement Guide—Component Side (1stlayer)

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PCB Layout—Component Side (1stLayer)

Technical Document Image Preview

PCB Layout—Bottom Side (4th layer)

Title Last Update Share Download
Evaluation Board User Guide 2015/06/01
Bill of Materials 2015/06/01
Part NumberFree SampleBuy From Authorized Distributor
EVB_RT7243GQW Not available Buy from Distributor
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