Abnormal condition for LPC1519JBD64E

[lev_nemets]

We are using LPC1519 microcontroller. If the user has incorrectly connected the input cable, it is possible that a + 15V (or minus 15V) battery may be connected to one of the PIO1 inputs (pin 51) through a 5.7K resistor. In this state, no other voltages will be applied to this microcontroller. Thus, the maximum possible current is less than 3 mA. Is it safe for the microcontroller or does it require additional protection?

[xiangjun_rong · Accepted solution]

Hi, Lev,

Pls refer to the following section limiting values in data sheet of LPC15xx. The I/O maximum voltage is 5.5V under the condition  VDD>2.4V. The I/O maximum voltage is 3.3V under the condition  the VDD=0V. 

BTW, for almost each pins, there are internal protection diode specifically designed for the protection of its internal devices from the damaging effects of excessive
static charge. The current must be less than 3mA as far as I know, if the I/O pin is exposed to 15V voltage with serial resistor in a short time, I think it is okay. But I suppose we never have a test for the scenario.

Hope it can help you

BR

XiangJun Rong

[1] The following applies to the limiting values:
a) This product includes circuitry specifically designed for the protection of its internal devices from the damaging effects of excessive
static charge. Nonetheless, it is suggested that conventional precautions be taken to avoid applying greater than the rated
maximum.
b) Parameters are valid over operating temperature range unless otherwise specified. All voltages are with respect to VSS unless
otherwise noted.