PN532 module excess heating and taking 330mA

[gmorfeus]

Hi,

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:smileyshocked: 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!

Gabrijel

[dominusdrr]

Can you put the device in reset and measure the current?

In theory when the reset pin is low, the device goes into low consumption and if the current is high, there is probably damage to the chip or something else that consumes a lot of current.

It is also possible that a very low impedance load is connected to the internal 3.3 regulator of the chip.

[gmorfeus · Accepted solution]

I just forgot about this post and I apologize for that. For anyone who might get to the similar problem, my solution was to connect VCC of pn532 to maximum 3.3V and not 5V. Looks like it's not 5V tolerant any it start to fail ending with complete failure after some time.

Gabrijel

[AIMSTEC]

PN532 MODULE V3 NOT WORKS ON 3.3V , im using adafruit lib. SCL , SDA, IRQ, RST pins. i added 3.3 1w resi. in series vcc pin at 5v but still its heated up. kindly help.

[gmorfeus]

Hi,

if you are using series resistor to drop voltage, 3.3Ohm is too small. PN532 uses around 100mA of current so your series resistor must be in the range of 12-17Ohm. I suggest putting 15Ohm if you don't mind dissipating power on that resistor (you'll be dissipating about 0.3W so use 0.5W or higher rating resistor). The better solution would be using an LDO.
Also, did you pull-up SCL and SDA to 3.3V? Pulling that to 5V might result in PN532 overheat and total failure as well...

Kind regards,
Gabrijel