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Richtek

2A, 5.5V, Low IQ ACOT Synchronous Step-Down Converter

EVB_RT5795AGQW

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The RT5795A is a full featured 5.5V, 2A, Advanced Constant-On-Time (ACOT) synchronous step-down converter with two integrated MOSFETs. The advanced COT operation allows transient responses to be optimized over a wide range of loads, and output capacitors to efficiently reduce external component count. The RT5795A provides up to 2.7MHz switching frequency to minimize the size of output inductor and capacitors.

Purpose

The RT5795A is an Advanced Constant-On-Time (ACOT) synchronous step-down converter with the input voltage range from 2.5V to 5.5V and provides 2A output current. This document explains the function and use of the RT5795A evaluation board (EVB), and provides information to enable operation, modification of the evaluation board and circuit to suit individual requirements.


Introduction

General Product Information

The RT5795A is a full featured 5.5V, 2A, Advanced Constant-On-Time (ACOT) synchronous step-down converter with two integrated MOSFETs. The advanced COT operation allows transient responses to be optimized over a wide range of loads, and output capacitors to efficiently reduce external component count. The RT5795A provides up to 2.7MHz switching frequency to minimize the size of output inductor and capacitors.


Product Feature

  • 2.5V to 5.5V Input Voltage Range
  • Advanced COT Control loop design
  • Fast Transient Response
  • Internal 100mΩ and 80mΩ Synchronous Rectifier
  • Highly Accurate VOUT Regulation Over Load/Line Range
  • Robust Loop Stability with Low-ESR COUT


Key Performance Summary Table

Key Features

Evaluation Board Number : PCB035_V1

Default Input Voltage

3.3V

Max Output Current

2A

Default Output Voltage

1.2V

Default Marking & Package Type

RT5795AGQW, WDFN-8SL 2x2

Operation Frequency

Fixed 2.7MHz



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

Power input supply voltage, 2.5V to 5.5V.

EN

Enable test point

Enable control input. Pull high to enable.

PGOOD

Power Ground

The exposed pad must be soldered to a large PCB and connected to GND for maximum thermal dissipation.

AGND

Analog Ground

Should be electrically connected to GND close to the device.

PGND

Power Ground

The exposed pad must be soldered to a large PCB and connected to PGND for maximum power dissipation.

VOS

No internal connection

Output voltage sense pin for the Internal Control Loop. Must be connected to output.

FB

Feedback test point

Feedback voltage input.

LX

Switch node test point

Switch node. The source of the internal high-side power MOSFET, and drain of the internal low-side (synchronous) rectifier MOSFET.



Power-up & Measurement Procedure

1. Apply a 12V nominal input power supply (2.5V < VIN < 5.5V) to the VIN and GND terminals.

2. Set the jumper at JP1 to connect terminals 2 and 3, connecting EN to enable operation.

3. Verify the output voltage (approximately 1.2V) 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 (R24, R29) between VOUT and GND with the midpoint connected to FB. The output is set by the following formula :

Technical Document Image Preview


Schematic, Bill of Materials & Board Layout

EVB Schematic Diagram

Technical Document Image Preview



Bill of Materials

Reference

Qty

Part Number

Description

Package

Manufacture

U4

1

RT5795AGQW

DC/DC Converter

WDFN-8SL 2x2

RICHTEK

C12, C13, C31

3

NC

C10, C14

2

C1608X7R1H104KT000N

0.1μF/±10%/50V/X7R

C-0603

TDK

C11

1

GRM31CR61A226KE19L

22μF/10V/X5R

C-1206

MURATA

C15

1

GRM31CR71E106KA12L

10μF/25V/X7R

C-1206

MURATA

L1

1

PIFE25201T-R47MS

0.47μH

2.5 x 2.0 mm

CYNTEC

R24

1

65.3kΩ

R-0603

R29

1

39.2k

R-0603

R30

1

100k

R-0603

R31

1

180k

R-0603



PCB Layout

Technical Document Image Preview

Top View

Technical Document Image Preview

Bottom View

Title Last Update Share Download
Evaluation Board User Guide 2015/10/27
Bill of Materials 2015/10/27
Gerber File 2015/10/27
Schematic 2015/10/27
Part NumberFree SampleBuy From Authorized Distributor
EVB_RT5795AGQW Not available Buy from Distributor
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