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PN532 module excess heating and taking 330mA

Question asked by Gabrijel Erman on May 10, 2018
Latest reply on May 18, 2018 by Fabian Romo



I've been working with a PN532 module connected to Wemos mini pro so PN532 was connected to 5V on Wemos. When feeding all from my laptop I didn't noticed anything strange (can't tell about current and I wasn't really paying attention if it gets hot). Anyway, after connecting all to laboratory power supply, I noticed the circuit using around 430mA, and also that PN chip gets really hot (I can't hold my finger on the chip for 1 second!). I have rechecked the connections but there was nothing wrong, so I switched the circuit on and let it work. It was working without any problems. OK, then I disconnected SPI wires (I am using the module in SPI mode), and connected only Vdd and GND of PN module to power supply. Current was 330mA at 5V and heating was here again. Then I connected all back to Wemos (and Vdd as well), plugged in USB and everything was working but PN is getting hot again and after some time it stops to read tags. If I switch off and let PN cool down, it read tags again (and so on.)  As I am reading in the datasheet, PN shall be using only 150mA at 5V and that's almost half the current mine is using! Did anyone experience similar current consumption and heating of PN chip? Thanks!