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6A, 18V, 650kHz, ACOT™ Synchronous Step-Down Converter

EVB_RT6236AHGQUF

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The RT6236AH is a high-performance 650kHz, 6A step-down regulator with internal power switches and synchronous rectifiers. It features quick transient response using its Advanced Constant On-Time (ACOT™) control architecture that provides stable operation with small ceramic output capacitors and without complicated external compensation, among other benefits. The input voltage range is from 4.5V to 18V and the output is adjustable from 0.7V to 8V. The proprietary ACOT™ control improves upon other fast response constant on-time architectures, achieving nearly constant switching frequency over line, load, and output voltage ranges. Since there is no internal clock, response to transients is nearly instantaneous and inductor current can ramp quickly to maintain output regulation without large bulk output capacitance. The RT6236AH is stable with and optimized for ceramic output capacitors. With internal 51mΩ switches and 18mΩ synchronous rectifiers, the RT6236AH displays excellent efficiency and good behavior across a range of applications, especially for low output voltages and low duty cycles. Cycle-by-cycle current limit provides protection against shorted outputs, input under-voltage lock-out, externally-adjustable soft-start, output under- and over-voltage protection, and thermal shutdown provide safe and smooth operation in all operating conditions. The RT6236AH is available in the UQFN-13JL 2x3 (FC) package, with exposed thermal pad.

Purpose

The RT6236AH is a Advanced Constant On-Time (ACOT™) control architecture step-down converter with the input voltage range from 4.5V to 18V and provides 6A output current. This document explains the function and use of the RT6236AH 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 RT6236AH is a high-performance 650kHz, 6A step-down regulator with internal power switches and synchronous rectifiers. It features quick transient response using its Advanced Constant On-Time (ACOT™) control architecture that provides stable operation with small ceramic output capacitors and without complicated external compensation, among other benefits. The input voltage range is from 4.5V to 18V and the output is adjustable from 0.7V to 8V. The proprietary ACOT™ control improves upon other fast response constant on-time architectures, achieving nearly constant switching frequency over line, load, and output voltage ranges. Since there is no internal clock, response to transients is nearly instantaneous and inductor current can ramp quickly to maintain output regulation without large bulk output capacitance. The RT6236AH is stable with and optimized for ceramic output capacitors. With internal 51mΩ switches and 18mΩ synchronous rectifiers, the RT6236AH displays excellent efficiency and good behavior across a range of applications, especially for low output voltages and low duty cycles. Cycle-by-cycle current limit provides protection against shorted outputs, input under-voltage lock-out, externally-adjustable soft-start, output under- and over-voltage protection, and thermal shutdown provide safe and smooth operation in all operating conditions. The RT6236AH is available in the UQFN-13JL 2x3 (FC) package, with exposed thermal pad.


Product Feature

  • Fast Transient Response
  • Advanced Constant On-Time (ACOT™) Control
  • 4.5V to 18V Input Voltage Range
  • Adjustable Output Voltage from 0.7V to 8V
  • 6A Output Current
  • 51mΩ Internal High-Side N-MOSFET and 18mΩ Internal Low-Side N-MOSFET
  • Steady 650kHz Switching Frequency
  • Up to 95% Efficiency
  • Optimized for All Ceramic Capacitors
  • Externally-Adjustable, Pre-Biased Compatible Soft-Start
  • Cycle-by-Cycle Current Limit
  • Input Under-Voltage Lockout
  • Output Over- and Under-Voltage Protection
  • Power Good Output
  • Thermal Shutdown

 

Key Performance Summary Table

Key Features

Evaluation Board Number : PCB057_V1

Default Input Voltage

12V

Max Output Current

6A

Default Output Voltage

1.2V

Default Marking & Package Type

RT6236AHGQUF, UQFN-13JL 2x3 (FC)

Operation Frequency

Steady 650kHz at all loads



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 and Connected to High-Side MOSFET Drain.

EN

Enable test point

High = Enable. Enable Control Input.

GND

Ground

Ground.

FB

Converter Feedback Input

Connect to output voltage feedback resistor divider.

NC

No Internal Connection

No Internal Connection.

SS

Soft-Start Control

A external capacitor should be connected to GND.

PVCC

Internal regulator output

5V Power Supply Output. A capacitor (typical 1µF) should be connected to GND.

PGOOD

Power good signal

Open Drain Power Good Output.

BOOT

Bootstrap supply test point

Bootstrap. This capacitor is needed to drive the power switch's gate above the supply voltage. It is connected between SW and BOOT pins to form a floating supply across the power switch driver. A 0.1µF capacitor is recommended for use.

SW

Switch node test point

Connect this pin to an external L-C filter.



Power-up & Measurement Procedure

1. Apply a 12V nominal input power supply (4.5V < VIN < 18V) to the VIN and GND terminals.

2. Set the jumper at JP2 to connect terminals 2 and 3, connecting EN to VIN through resistor R5, to enable operation.

3. Verify the output voltage (approximately 1.2V) between VOUT and GND.

4. Connect an external load up to 5A to the VOUT and GND terminals and verify the output voltage and current.



Output Voltage Setting

Set the output voltage with the resistive divider (R2, R3) 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

C1, D1, L2

3

NC

C3, C4

2

UMK325BJ106MM-T

10µF/50V/X5R

C-1210

TAIYO YUDEN

C5

1

C1608X5R1E105KT000E

1µF/25V/X5R

C-0603

TDK

C6, C8, C12

3

C1608X7R1E104KT000N

0.1µF/50V/X7R

C-0603

TDK

C7

1

C1608X7R1E104KT000N

3.9nF/50V/X7R

C-0603

TDK

C9, C10, C11

3

C3225X5R1E226MT

22µF/25V/X5R

C-1210

TDK

J1

1

VIN

Golden pin

J2, J6

2

GND

Golden pin

J3

1

VOUT

Golden pin

L1

1

SPM6530T-1R0M120

Inductor, SMT, 1µH, 13A, 7.81mΩ

L-SPM6530

TDK

74437368010

Inductor, SMT, 1µH/14.5A/3mΩ

L-SPM6530

WE

R2

1

17k

R-0603

R3

1

24k

R-0603

R4, R5

2

100k

R-0603

CP1

1

short

U1

1

RT6236AHGQUF

DC/DC Converter

UQFN-13JL 2x3 (FC)

RICHTEK



PCB Layout

Technical Document Image Preview

Top View (1st layer)

Technical Document Image Preview

PCB Layout—Inner Side (2nd Layer)

Technical Document Image Preview

PCB Layout—Inner Side (3rd Layer)

Technical Document Image Preview

Bottom View (4th Layer)

Title Last Update Share Download
Evaluation Board User Guide 2015/12/25
Bill of Materials 2015/12/25
Gerber File 2015/12/25
Schematic 2015/12/25
RT6236A/RT6236B

6A, 18V, 650kHz, ACOT™ 同步降压型转换器

RT6236A/RT6236B

RT6236A/B为高性能,操作频率650kHz,6A输出电流,内建功率开关与同步整流元件的降压型 DC/DC 转换器。藉由先进恒定导通时间(ACOT™)模式控制的架构可在输出使用小型封装的陶瓷电容的情形下,达到稳定的操作与快速的瞬时响应,此外并不需要外加复杂的补偿元件。输入电压范围4.5V至18V,输出可调范围0.7V至8V。专有的 ACOT™ 模式控制改善了一般恒定导通时间控制架构的瞬时响应特性,在输入电压、输出电压与负载变动的范围内达到切换频率近乎恒定的操作。由于不是由内部频率讯号进行开关切换的控制,电感电流可在不依赖采用大输出电容的设计下快速的变化,达成瞬时的响应特性并调节稳定输出电压。RT6236A/B可在输出采用陶瓷电容的条件下达到稳定的优化设计,内部具备51mΩ的功率开关与 18mΩ 的同步整流元件,得以在不同的应用范围内达到优越的转换效率与工作特性,特别是在低占空比与低电压输出的操作条件。此外,逐周期的限流机制对输出短路状况的保护、输入低电压锁定、可外部调整设计的缓起动功能、输出低电压保护、输出过电压保护与过温关机等保护机制功能,提供在所有工作条件下的安全与简易操作方式。RT6236A/B 支持UQFN-13JL 2x3 (FC)的封装规格。

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