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MAX18000 stops working

Category: Hardware
Product Number: MAX18000


We have designed and made a few standalone boards using MAX18000. These boards step up 3.67V from a 19Ahr lithium thionyl chloride cell (with a supercap in parallel) to 3.9V which feeds a board with an MCU and GSM modem.

This board was designed because due to the poor quality of cells, the current requirement for the GSM modem could not be met during transmissions.

We have seen 2 kinds of faults with this circuit.

1. The input and output voltage is the same, MAX18000 does not seem to be doing anything. This is the most common case, which appears usually when the input voltage (of the cell) has dropped a bit (~3.3V). Still, we would expect the MAX18000 IC to continue switching to provide the needed 3.9V on the output side and not merely just pass it through.

2. The input voltage is a healthy 3.5V or 3.6V but the output voltage drops to 0V sometime during operation. MAX18000 does not seem to be doing anything in this case as well. Disconnecting the input battery and reconnecting it again fixes the issue and "restarts" MAX18000. Why could this be happening?

Any help will be appreciated, thank you.

[edited by: GenevaCooper at 2:23 PM (GMT -5) on 20 Feb 2024]