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.

Feature(s)

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
Resistor Programmable Current Limit by Low-side R_DSON 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
Halogen and Antimony Free. “Green” Device

Application(s)

Notebook Computer, AIO PC
Low-voltage Distribute Power
I/O Supplies

Specifications & Technical Documents

Product Parameters

Efficiency (%)	93
Frequency (Hz)	100K to 700K
MaximumInput Voltage (V)	26
MinimumInput Voltage (V)	4.5
Output Voltage (V)	0.75 to 5.5
Type	Buck

Technical Documents

Recommended Soldering Techniques

TN1.pdf

Purchase & Availability

Something went wrong with your request. Please try again later. If this problem continues, please contact Diodes support for assistance.

Product Change Notices (PCNs)

A PCN may only apply to specific orderable part numbers in this datasheet. Please refer to the corresponding PCN to see the exact orderable part number(s) affected.

PCN #	Issue Date	Implementation Date	Subject
PCN-2770	2025-10-30	2025-10-30	Add Fab Site Code, Country of Diffusion (COD) and Assembly Site Origin (ASO) on Product and Shipping Labels for all Diodes Products

AP3591 (Obsolete)