Datasheet

PCA6408A All information provided in this document is subject to legal disclaimers. © NXP B.V. 2012. All rights reserved.
Product data sheet Rev. 1 — 27 September 2012 14 of 40
NXP Semiconductors
PCA6408A
Low-voltage, 8-bit I
2
C-bus and SMBus I/O expander
9.2 Power-on reset requirements
In the event of a glitch or data corruption, PCA6408A can be reset to its default conditions
by using the power-on reset feature. Power-on reset requires that the device go through a
power cycle to be completely reset. This reset also happens when the device is
powered on for the first time in an application.
The two types of power-on reset are shown in Figure 15
and Figure 16.
Table 11 specifies the performance of the power-on reset feature for PCA6408A for both
types of power-on reset.
Fig 13. High-value resistor in parallel
with the LED
Fig 14. Device supplied by a lower voltage
002aah278
LED
V
DD(P)
Pn
100 kΩ
V
DD
002aah279
LED
V
DD(P)
Pn
3.3 V 5 V
Fig 15. V
DD(P)
is lowered below 0.2 V or 0 V and then ramped up to V
DD(P)
Fig 16. V
DD(P)
is lowered below the POR threshold, then ramped back up to V
DD(P)
002aag960
V
DD(P)
time
ramp-up ramp-down
(dV/dt)
r
(dV/dt)
f
re-ramp-up
(dV/dt)
r
time to re-ramp
when V
DD(P)
drops
below 0.2 V or to V
SS
t
d(rst)
002aag961
V
DD(P)
time
ramp-down
(dV/dt)
f
ramp-up
(dV/dt)
r
time to re-ramp
when V
DD(P)
drops
to V
POR(min)
− 50 mV
t
d(rst)
V
I
drops below POR levels