3S Li-ion Battery Protection Board (Code 23) — Product Introduction

Overview

This protection board employs the PWCHIP PW7126 protection IC and two PW4406A MOSFETs to provide complete overcharge, over-discharge, overcurrent, and short-circuit protection for 3S lithium-ion battery packs (11.1 V nominal, 12.6 V fully charged). It supports a continuous discharge current of 3 A and an overcurrent protection threshold of approximately 7 A. The integrated PW4243 asynchronous buck charger accepts DC input from 15 V to 24 V and delivers up to 2 A charge current to the battery.

Specifications

Parameter	Specification
Battery Type	3S (3-series Li-ion, 11.1 V nominal, 12.6 V fully charged)
Continuous Discharge Current	3 A
Overcurrent Protection Threshold	Approx. 7 A
Protection IC	PW7126
MOSFETs	PW4406A × 2
MOSFET Package	SOP-8
Charging Input	DC 15 V–24 V
Charging IC	PW4243
Charging Topology	Asynchronous buck charging
Battery-Side Charging Current	2 A

Key ICs

PW7126 is a dedicated 3-cell lithium-ion protection IC integrating overcharge, over-discharge, overcurrent, and short-circuit protection. It supports high-precision voltage detection.

PW4243 is an asynchronous switching buck charger with conversion efficiency up to 90 %. It accepts 15 V–24 V input and steps it down to 12.6 V at 0.5 A–2 A for charging 3S battery packs.

Key Features

· Single-board protection and charging solution for 3S battery packs

· PW4243 asynchronous buck charging supports 15 V–24 V input

· Compatible with 18 V, 20 V, and 24 V adapters, delivering 2 A charge current

· Buck charging topology optimized for high-voltage DC supply scenarios

· PW7126 protection IC plus two PW4406A MOSFETs for 7 A overcurrent protection

· Suitable for industrial-grade DC-powered 3S battery pack applications

Schematic

Code 23 Schematic

PCB Photo

Code 23 PCB Photo

Typical Applications

Industrial equipment, security monitoring, power tools, solar power systems, in-vehicle devices.

Wiring Notes

Connect the battery as indicated on the schematic. The charge/discharge terminals are P+ and P-.

Documentation & Technical Support

We provide chip samples, technical documentation, and circuit design support. For more information or to request materials, please contact us at support@pwchip.com or reach an authorized distributor at https://www.pwchip.com/page/180.html.