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AP2171SG-13

Load switch, 1.2-5.5V, 40mOhm, adj current limit 0.15-2A, reverse block, SOT-23-5

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Manufacturer Part：

AP2171SG-13

Package：

SOT-23-5 (2.90 x 1.60 x 1.10 mm)

Description

Product Overview

The AP2171SG-13 from Diodes Incorporated is a single-channel load switch with adjustable current limit in a SOT-23-5 package. It features an input voltage range of 1.2 V to 5.5 V, a low 40 mOhm on-resistance, and programmable current limiting from 0.15 A to 2.0 A for USB and hot-swap power rail protection.

Key Specifications

Input Voltage Range	1.2 V to 5.5 V
On-Resistance	40 mOhm typical
Current Limit Range	0.15 A to 2.0 A (adjustable)
Quiescent Current	1 uA typical (off state)
Reverse Current Blocking	Yes
Output Discharge	Integrated
Enable Input	Active high
Fault Flag Output	Open-drain
Operating Temperature	-40°C to +85°C

Features

Low RDS(on) of 40 mOhm for minimal voltage drop
Adjustable current limit via external resistor
Reverse current blocking prevents backfeed
Integrated output discharge for rapid power-down
Thermal shutdown protection
Open-drain fault flag indicates overcurrent or thermal events
Controlled turn-on slew rate limits inrush current
Compact SOT-23-5 package

Applications

USB port power switching and protection
Hot-swap power rail management
Portable device power distribution
SSD and storage device power sequencing

Product Introduction:AP2171SG-13 Product Introduction

The AP2171SG-13 from Diodes Incorporated is a single-channel integrated load switch designed for power rail switching and protection in portable electronics and USB-powered systems. It integrates a 40 mOhm N-channel MOSFET with adjustable current limiting, reverse current blocking, and controlled turn-on slew rate in a compact SOT-23-5 package. The current limit is programmable from 0.15 A to 2.0 A via a single external resistor, allowing designers to tailor the protection level for different load requirements. Reverse current blocking prevents backfeed from the output to the input when the switch is off, protecting upstream circuitry. The integrated output discharge resistor rapidly discharges the output capacitance when the switch is turned off, ensuring a clean power-down sequence. An open-drain fault flag (FLG) signals overcurrent, short-circuit, or thermal shutdown conditions to the system controller. The controlled turn-on slew rate limits inrush current during hot-plug events, preventing voltage droops on the input supply.

Working Principle:AP2171SG-13 Working Principle

The AP2171SG-13 operates through four functional blocks: (1) The power switch is an N-channel MOSFET with 40 mOhm on-resistance, controlled by the EN (enable) input. When EN is driven high, the gate driver applies a controlled ramp to the MOSFET gate, producing a slew-rate-limited turn-on that limits inrush current into the output capacitance. When EN is driven low, the MOSFET turns off rapidly. (2) The current limit circuit monitors the MOSFET current and compares it against the threshold set by the external resistor on the ILIM pin. When the current exceeds the limit, the MOSFET gate voltage is reduced to regulate the current at the set value. If the overcurrent persists, the thermal shutdown activates. (3) The reverse current blocking circuit uses a comparator to detect when VOUT exceeds VIN, disabling the MOSFET to prevent current flow from output to input. (4) The fault flag (FLG) is an open-drain output that asserts low during overcurrent, short-circuit, or thermal shutdown events, providing real-time status to the host controller.

Pin Description:AP2171SG-13 Pin Definition and Functions

Pin No.	Pin Name	Function
1	VIN	Input voltage (1.2-5.5 V)
2	GND	Ground
3	EN	Enable input (active high)
4	ILIM	Current limit set resistor (to GND)
5	VOUT	Output voltage (to load)

Application Scenarios:In which products and applications isAP2171SG-13 used

USB port power switching where the adjustable current limit protects the USB host controller from overcurrent faults and the reverse blocking prevents backfeed from peripheral devices
Hot-swap power rail management in server and telecom cards where controlled turn-on slew rate limits inrush current during card insertion
Portable device power distribution using multiple AP2171 devices to independently enable and protect individual power domains with fault reporting
SSD power sequencing where the integrated output discharge ensures rapid and clean power-down during hot-unplug events

Alternative Models:What chips are recommended as replacements for AP2171SG-13

Model	Brand	Ron	Ilim	Package
AP2172SG-13	Diodes	40 mOhm	Fixed	SOT-23-5
TPS22916DBVR	TI	50 mOhm	–	SOT-23-5
NCP380LSN05AAT1G	onsemi	50 mOhm	Adj	TSOT-23-6
FDC6324L	onsemi	Discrete	–	SOT-23-6
SIP32431DR3-T1-GE3	Vishay	44 mOhm	–	TSOT-23-5