Product Introduction

Product parameters

Funtion:PFM Step-up Multi-cell Battery Charger IC

Opration Mode:Switch

Battery:Lithium-ion,LiFEPO4 and Lead-Acid Battery

Vout Range:0V-18V

Vin Range:2.7V - 6.5V

Operating Current:280uA

Solar Panel charge:Yes

Chip Temperature Regulation:No


Chip Enable:Yes

On-chip Power MOSFET:No

General Description

CN3305 is a PFM mode step-up battery charge management IC with operating voltage range between 2.7V to 6.5V. It is specially designed for multi-cell lithium-ion, LiFePO4 and Lead Acid battery charge management with fewer external components. CN3305 adopts constant current and quasi-constant voltage(Quasi-CVTM) mode to charge battery.

On power up, CN3305 enters charging mode, the external N-channel MOSFET is turned on, inductor current rises. When inductor current reaches upper threshold, the N-channel MOSFET is turned off, inductor is discharged, the energy stored in inductor is transferred to battery. When the inductor current is discharged to its lower threshold, the N-channel MOSFET is turned on again. When FB pin voltage reaches 1.205V(Typ.) for the first time, CN3305 enters quasi-CV mode, in which the charge current is reduced. The charge process will not be terminated until FB voltage reaches 1.205V for the second time. In termination mode, the N-channel MOSFET is turned off. When FB voltage falls below recharge threshold, the CN3305 enters charge mode again. CN3305’s switching frequency can be up to 1MHz, which makes a small-profile inductor usable.

If battery voltage is lower than input voltage by a diode drop, CN3305 will increase the off time to 5us to reduce the charge current as a protection for  battery with the joint action of external N-channel and P-channel MOSFET.

The other features include status indication, etc.

CN3305 is available in 8-pin SOP package.


l  Lithium-ion,LiFEPO4 and Lead-Acid Battery

l  Power Bank,

l  Electric Appliance

l  Audio System

l  Standalone Battery Charger


l  Input Voltage Range2.7V to 6.5V

l  Operating Current280uA@VIN=5V

l  Suitable for Lithium-ion, LiFePO4 and Lead-Acid Batteries

l  Inductor Current Detection

l  Switching Frequency up to 1MHz

l  Quasi-CV mode to Compensate for the Voltage Loss on Battery Internal Resistance and Trace Resistance

l  Automatic Recharge

l  Output Power up to 35W

l  Protection for Low Battery Voltage and Short Battery

l  Automatic Adaptability to Input Supply with Limited Driving Capability

l  Battery Overvoltage Protection

l  Status Indication

l  Operating Temperature :-40 to 85

l  Available in SOP8 Package

l  Lead-free, rohs-Compliant and Halogen Free

Tools and Documents




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