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RT6276BHGQUF Step-Down Converter Evaluation Board

EVB_RT6276BHGQUF

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The RT6276B is an advanced constant on-time (ACOT) mode synchronous buck converter. The main control loop of the RT6276B using an advanced constant on-time (ACOT) mode control which provides a very fast transient response. The RT6276B operates from 4.5V to 23V input voltage, the output voltage can be programmed between 0.6V to 5.1V.

Purpose

The RT6276B is an advanced constant on-time (ACOT) mode synchronous buck converter with the input voltage range from 4.5V to 23V and provides 6A output current. This document explains the function and use of the RT6276B 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 RT6276B is an advanced constant on-time (ACOT) mode synchronous buck converter. The main control loop of the RT6276B using an advanced constant on-time (ACOT) mode control which provides a very fast transient response. The RT6276B operates from 4.5V to 23V input voltage, the output voltage can be programmed between 0.6V to 5.1V.


Product Feature

  • Input Voltage Range : 4.5V to 23V
  • 6A Output Current
  • ACOTMode Performs Fast Transient Response
  • ACOTArchitecture to Enable All MLCC Output Capacitor Usage
  • Fixed 500kHz Switching Frequency
  • High Efficient Internal Power MOSFET Switch 30mΩ (High-Side) and 15mΩ (Low-Side)
  • Adjustable Output Voltage from 0.6V to 5.1V
  • Pre-biased Soft-Start
  • Cycle-by-Cycle Over-Current Protection
  • Input Under-Voltage Lockout
  • Thermal Shutdown Protection
  • Output Over/Under-Voltage Protection

Key Performance Summary Table

Key Features

Evaluation Board Number: PCB091_V1

Default Input Voltage

12V

Max Output Current

6A

Default Output Voltage

3.3V

Default Marking & Package Type

RT6276BHGQUF, UQFN-12HL 3x3 (FC)

Operation Frequency

Steady 500kHz at all loads



Bench Test Setup Conditions

Headers Description and Placement

Technical Document Image Preview

Carefully inspect all the components used in the EVB according to the following Bill of Materials table, and then make sure all the components are undamaged and correctly installed. If there is any missing or damaged component, which may occur during transportation, please contact our distributors or e-mail us at 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. Support 4.5V to 23V Input Voltage. Must bypass with a suitable large ceramic capacitor at this pin.

EN

Enable test point

Enable control. Pull this pin high to turn on the Buck. Do not leave this pin floating.

GND

Ground

Ground.

PGOOD

Power good test point

Power good Indicator. Open drain output when the output voltage is within 90% to 120% of regulation point.

FB

Feedback voltage input

The pin is used to set the output voltage of the converter to regulate to the desired voltage via a resistive divider. Feedback reference = 0.6V.

VCC

Internal regulator output

5V linear regulator Output for Internal Control Circuit. A capacitor (typical 1µF) should be connected to AGND. Don’t connect to external Load.

BOOT

Bootstrap supply test point

Bootstrap supply for high-side gate driver. Connect a 0.1µF ceramic capacitor between the BOOT and SW pins.

LX

Switch node test point

Connect this pin to an external L-C filter.

BYP

Bypass test point

Bypass input for the internal LDO. BYP is externally connected to the output of switching regulator. When the BYP voltage rises above the bypass switch turn-on threshold, the LDO regulator shuts down and the VCC pin is connected to the BYP pin through an internal switch.

ILIMT

Current limit seeting

Current limit setting pin. The current limit is set to 4A, 6A or 8A when this pin is pull low, floating or pull high respectively.



Power-up & Measurement Procedure

1. Connect input power (4.5V < VIN < 23V) 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. Set the jumper at J7 to connect terminals 2 and 3, connecting EN to VIN through resistor REN, to enable operation.

4. Verify the output voltage (approximately 3.3V) between VOUT and GND.

5. 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 (R4, R5) between VOUT and GND with the midpoint connected to FB. The output is set by the following formula:

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Schematic, Bill of Materials & Board Layout

EVB Schematic Diagram

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Bill of Materials

Reference

Qty

Part Number

Description

Package

Manufacturer

U1

1

RT6276BHGQUF

DC-DC Converter

UQFN-12HL 3x3 (FC)

RICHTEK

C3

1

C1608X5R0J475KT

4.7µF/6.3V/0603

C-0603

TDK

C4

1

C1608X5R1E105KT000E

1µF/25V/X5R/0603

C-0603

TDK

C6, C9, C15, C16

4

C1608X7R1H104KT000N

0.1µF/50V/X7R/0603

C-0603

TDK

C7

1

0603N680J500

68pF/50V/NPO/0603

C-0603

WALSIN

C8, C10

2

UMK325BJ106MM

10µF/50V/X5R/1210

C-1210

TAIYO YUDEN

C11, C12

2

C3225X5R1E226MT

22µF/25V/X5R/1210

C-1210

TDK

L1

1

7443552200

2µH

L-GSCDK104

WE

R3, R19

2

WR06X1003FTL

100k/0603

R-0603

WALSIN

R4

1

RTT039092FTP

90.9k/0603

R-0603

WALSIN

R5

1

WR06X2002FTL

20k/0603

R-0603

WALSIN

R11

1

WR06X3602FTL

36k/0603

R-0603

WALSIN

R12, R15

2

WR06X000PTL

0R/0603

R-0603

WALSIN

R16

1

WR06X7502FTL

75k/0603

R-0603

WALSIN

R18

1

WR06X1002FTL

10k/0603

R-0603

WALSIN



PCB Layout

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Top View (1st layer)

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PCB Layout—Inner Side (2nd Layer)

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PCB Layout—Inner Side (3rd Layer)

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Bottom View (4th Layer)

Title Last Update Share Download
Evaluation Board User Guide 2017/12/28
Bill of Materials 2017/12/28
Gerber File 2017/12/28
Schematic 2017/12/28
RT6276A/RT6276B

23V, 6A, 500kHz, ACOT® 同步Buck轉換器

RT6276A/RT6276B

RT6276A/B是簡單易用的6A同步Buck轉換器,輸入電壓範圍為4.5V~23V,內部集成高精度0.6V參考電壓源和低RDS(ON)功率開關,使用晶核倒裝的UQFN-12HL 3x3封裝,採用改進型固定導通時間 (ACOT®) 控制架構,具有超快速的瞬態回應,週邊元件少,在各種運作條件下都具有幾乎不變的開關切換工作頻率,具有很高的輸出電壓調節精度。RT6276A在輕載時自動進入PSM模式以維持高轉換效率,RT6276B採用強制PWM工作模式以滿足嚴格的電壓調節精度要求。它對上、下橋的電流都進行檢測以獲得強健的過流保護性能,逐週期過流保護可最大程度地避免輸出短路、過流和電感飽和等現象帶來災難性的後果,內建的軟啟動功能可避免啟動期間出現大的浪湧電流。它還具有輸入欠壓鎖定保護、輸出欠壓/過壓保護、過熱保護 (熱關機) 等安全機制,確保其在各種工作條件下均可穩定運行。RT6276A/B採用UQFN-12HL 3x3 (FC) 封裝。

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