CS5095E three-cell lithium battery boost charging circuit

I've done one before

CN3703 three-cell lithium battery series step-down charging circuit:

https://oshwhub.com/Aknice/cn3703-san-jie-li-dian-chi-xiang-ya-chong-dian-dian-lu

The boost charging circuit mentioned in it is this one

Introduction

CS5095E is a power management chip with 5V input voltage and three-cell lithium battery charging in series, supporting a maximum of 1.2A.

There is a charging LED indicator light. When it is on, it means charging. When it is fully charged, it goes off. If there is no battery installed, it will flash at a frequency of 1.6Hz.

The LED light here is green, I suggest you use red.

Please see the attachment for detailed parameters. Here is a detailed description of the NTC function.

NTC function

This is the description of NTC from the official document, where R3 is an 82k ohm resistor and R_NTC is a negative temperature coefficient resistor, that is, as the temperature increases, the resistor value decreases. Based on this principle, it is judged whether the chip is overheated during charging.

R_NTC is a 100k ohm negative temperature coefficient resistor. If this function is not needed:

Just connect an ordinary 100k ohm resistor

or

The official document states that if the NTC function is not needed, just connect a high level of 1.84v. You can connect the input 5V here, but it is not done on the circuit board. You need to change the wiring on the circuit board yourself.

The following actual measurement was performed by connecting a 100k ohm negative temperature coefficient resistor. In fact, it is not hot during charging, and the NTC pin voltage is about 900mv.

Actual measurement

I use three Panasonic 3400 mAh 18650 batteries. The voltage of each cell starts charging at 3.3V, and the time is 13:45.

When charging, the LED light will light up

After full charging, the LED light turns off, and the final full charge (4.2V per section) time is 0:00

It takes 10 hours and 15 minutes to charge three lithium batteries from 3.3V to 4.2V, that is, from only 10~20% to full charge.

In fact, charging does not have 1A, but I don’t have a voltage and ammeter to measure power, so I can’t measure it.

Summarize

The advantage is that 5v can charge 3 lithium batteries, which is more convenient.

The disadvantages are also obvious, lower power leads to longer charging time.

Not recommended, it is recommended to use CN3703 step-down charging