That's interesting, the P87LPC764 data sheet doesn't state a Vdd_rise_time(max).

The NXP P89LPC935 data sheet does state a Vdd_rise_time(max) and Vdd_fall_time(max)
Listed here: page 57 of the data sheet.
(dV/dt)r rise rate of VDD - - 2 mV/µs (max)
(dV/dt)f fall rate of VDD - - 50 mV/µs (max)

My interpretation of these parameters are

The Vdd of the P89LPC935 should rise faster than 2 mV/µs and fall faster than 50 mV/µs.

Data sheet here
http://www.standardics.nxp.com/products/lpc900/datasheet/p89lpc933.p89lpc934.p89lpc935.p89lpc936.pdf

Can anyone confirm my interpretation?


If my interpretation looks ok, then the impedance of Vdd supplied to the LPC935 has to take in account
any large capacitance that might cause Vdd_rise_time(max) to be slower than 2 mV/µs

I look forward to other peoples comments.

Regs
Joe