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Choosing a battery charger chip

A project log for OpenAirMonitor

A solar-powered, outdoor air quality monitor that transmits data over LoRaWAN and Bluetooth LE

Gerrit NiezenGerrit Niezen 10/22/2021 at 09:000 Comments

With the current global chip shortage it can be challenging to find the right chip for your project that's actually in stock. I want to share some of my own challenges and what the options are. First up: What LiPo battery charger chips can be used with solar panels?

BQ24074

I first came across Texas Instrument's BQ24074 while looking at Adafruit's Universal USB / DC / Solar LiPo charger, which replaced their earlier MCP73781-based charger. It's relatively inexpensive ($0.81) and has an input voltage of up to 10V. Unfortunately this chip was out of stock when I ordered my board for SMT assembly, so I had to consider alternatives.

LT3652

Analog Device's LT3652 is used in Sparkfun's Sunny Buddy (MPPT Solar Charger), but it's a lot more expensive (around $5) than other chips and was also out of stock at the time of ordering.

 CN3065 / CN3063

Consonance Electronic's CN3065 is used in Seeed Studio's LiPo Rider boards, as well as many low-cost solar battery charger boards on eBay. It's even cheaper than the BQ24074 at around $0.50, and it was available in its SOP8 package version CN3063 at JLCPCB when I placed my order. While it has been working great so far, it only has an input voltage of 6V, which could cause issues if you get high peak voltages on your solar panel over an extended period of time.

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