AP3591

Document number: DS36906 Rev. 1 - 2

1 of 18

www.diodes.com

March 2014

© Diodes Incorporated

AP3591

A Product Line of

Diodes Incorporated

SINGLE PHASE SYNCHRONOUS BUCK CONTROLLER

Description

The AP3591 is a synchronous adaptive on-time buck controller

providing high efficiency, excellent transient response and high DC

output accuracy for low voltage regulation in notebook application.

The constant-on-time PWM control scheme handles wide input/output

voltage ratios with ease and features small external component count

and fast transient response.

The operation mode is selectable by EN voltage. A Diode Emulation

Mode (DEM) is activated for increasing efficiency at light loads, while

PWM mode is activated only for low noise operation. The AP3591

also

integrates

internal

Soft-start,

UVLO,

OVP,

OTP,

and

programmable OCP to protect the circuit. A Power Good signal is

employed to monitor the output voltage.

The AP3591 is available in U-QFN3535-14 package.

Features



Fixed

Frequency

Constant

On-time

Control;

Resistor

Programmable Frequency Adjustable from 100kHz to 700kHz



Good Stability Independent of the Output Capacitor ESR



Quick Load Step Response



Input Voltage Range: 4.5V to 26V



Output Voltage Range: 0.75V to 5.5V



CCM/DEM Mode Selection



Integrated Bootstrap Diode



Sense



Integrated Negative Over Current Limit



Integrated OVP/UVP and Over Thermal Shutdown Function



Power Good Indicator



Internal Soft-start



Integrate Output Discharge (Soft-stop)



Safe Start-up into Pre-biased Loads



Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2)



Halogen and Antimony Free. “Green” Device (Note 3)

Pin Assignments

(Top View)

U-QFN3535-14

Applications



Notebook Computer, AIO PC



Low-voltage Distribute Power



I/O Supplies

Notes:

1. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS) & 2011/65/EU (RoHS 2) compliant.

2. See http://www.diodes.com/quality/lead_free.html for more information about Diodes Incorporated’s definitions of Halogen- and Antimony-free, "Green"

and Lead-free.

3. Halogen- and Antimony-

free "Green” products are defined as those which contain <900ppm bromine, <900ppm chlorine (<1500ppm total Br + Cl) and

<1000ppm antimony compounds.

VOUT

VDD

FB

PGOOD

LGATE

TON

UGATE

PHASE

CS

VDDP

Pin 1 Mark

EP

1

14

2

3

4

5

6

7

8

9

10

11

12

13