Category: Hardware
Product Number: MAX17263
We are designing a battery powered product and have incorporated a MAX17263 fuel gauge chip. We have 5 LEDS attached to this unit wired as LED0 to LED4 from figure 3 in the datasheet. We are seeing some odd behaviour with one of the LED outputs. For testing i have set the unit in custom LED drive mode and by sending the following bits to the custom LED register i get the following output on the LEDs:
0x00 - 00000
0x01 - 10000
0x02 - 01001 x LED4 lights about 75% brightness when should be off
0x03 - 11000
0x04 - 00100
0x05 - 10100
0x06 - 01101 x LED4 lights about 75% brightness when should be off
0x07 - 11100
0x08 - 00011 x LED4 lights about 75% brightness when should be off
0x09 - 10011 x LED4 lights about 75% brightness when should be off
0x0a - 01011 x LED4 lights about 75% brightness when should be off
0x0b - 11011 x LED4 lights about 75% brightness when should be off
0x0c - 00111 x LED4 lights about 75% brightness when should be off
0x0d - 10111 x LED4 lights about 75% brightness when should be off
0x0e - 01111 x LED4 lights about 75% brightness when should be off
0x0f - 11111 x LED4 lights about 75% brightness when should be off
0x10 - 00001
0x11 - 10001
0x12 - 01001
0x13 - 11001
0x14 - 00101
0x15 - 10101
0x16 - 01101
0x17 - 11101
0x18 - 00011
0x19 - 10011
0x1a - 01011
0x1b - 11011
0x1c - 00111
0x1d - 10111
0x1e - 01111
0x1f - 11111
0x01 - 10000
0x02 - 01001 x LED4 lights about 75% brightness when should be off
0x03 - 11000
0x04 - 00100
0x05 - 10100
0x06 - 01101 x LED4 lights about 75% brightness when should be off
0x07 - 11100
0x08 - 00011 x LED4 lights about 75% brightness when should be off
0x09 - 10011 x LED4 lights about 75% brightness when should be off
0x0a - 01011 x LED4 lights about 75% brightness when should be off
0x0b - 11011 x LED4 lights about 75% brightness when should be off
0x0c - 00111 x LED4 lights about 75% brightness when should be off
0x0d - 10111 x LED4 lights about 75% brightness when should be off
0x0e - 01111 x LED4 lights about 75% brightness when should be off
0x0f - 11111 x LED4 lights about 75% brightness when should be off
0x10 - 00001
0x11 - 10001
0x12 - 01001
0x13 - 11001
0x14 - 00101
0x15 - 10101
0x16 - 01101
0x17 - 11101
0x18 - 00011
0x19 - 10011
0x1a - 01011
0x1b - 11011
0x1c - 00111
0x1d - 10111
0x1e - 01111
0x1f - 11111
It seems that if LED1 is on without LED0, or LED3 is on, then LED4 lights with ~75% brightness.
This is the fuel gauge schematic
And this connects to a separate LED daughter board. We have dropped the current limiting resistors to 30ohms since this schematic was published.
We are seeing the same issue across both main boards we have tested and both LED boards.
Any thoughts?