3S Li-ion Battery Protection Board (Code 22) — Product Introduction

Overview

This protection board is based on the PWCHIP PW7126 protection IC and two PW4406A MOSFETs, providing 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 delivers a 3 A continuous discharge current and an approximately 4 A overcurrent protection threshold. The integrated PW4000 synchronous buck-boost charger supports USB/DC inputs of 5 V / 2 A, 9 V / 2 A, and 12 V / 2 A, with a battery-side charging current of 1.7 A.

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. 4 A
Protection IC	PW7126
MOSFETs	PW4406A × 2
MOSFET Package	SOP-8
Charging Input	USB/DC 5 V / 2 A, 9 V / 2 A, 12 V / 2 A
Charging IC	PW4000
Charging Topology	Buck-boost charging
Battery-Side Charging Current	1.7 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.

PW4000 is a synchronous switching buck-boost charger with conversion efficiency up to 95 %. It accepts 5 V–20 V input and regulates it to 12.6 V output at 0.5 A–1.7 A for charging 3S battery packs.

Key Features

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

· PW4000 buck-boost charger supports 5 V–20 V wide-range input

· Compatible with 5 V USB, 9 V, and 12 V adapters, delivering 1.7 A charge current

· Synchronous switching topology with up to 95 % efficiency

· PW7126 protection IC plus two PW4406A MOSFETs for 4 A overcurrent protection

· Ideal for 3S battery packs powered by multiple input voltage sources

Schematic

Code 22 Schematic

PCB Photo

Code 22 PCB Photo

Typical Applications

Power tools, portable vacuum cleaners, electric scooters, high-capacity 3S battery products, 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.