pca9539 datasheet

V
CC
Ramp-Up
Time to Re-Ramp
Time
Ramp-Down
V
IN
drops below POR levels
V
CC_RT
V
CC_FT
V
CC_TRR_VPOR50
V
CC
Ramp-Up Re-Ramp-Up
Time to Re-Ramp
Time
Ramp-Down
V
CC_RT
V
CC_RT
V
CC_FT
V
CC_TRR_GND
PCA9539
SCPS130G –AUGUST 2005–REVISED JUNE 2014 www.ti.com
10 Power Supply Recommendations
10.1 Power-On Reset Requirements
In the event of a glitch or data corruption, PCA9539 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 32 and Figure 33.
Figure 32. V
CC
Is Lowered Below 0.2 V Or 0 V And Then Ramped Up To V
CC
Figure 33. V
CC
Is Lowered Below The Por Threshold, Then Ramped Back Up To V
CC
Table 8 specifies the performance of the power-on reset feature for PCA9539 for both types of power-on reset.
Table 8. Recommended Supply Sequencing And Ramp Rates
(1)
PARAMETER MIN TYP MAX UNIT
V
CC_FT
Fall rate See Figure 32 1 100 ms
V
CC_RT
Rise rate See Figure 32 0.01 100 ms
V
CC_TRR_GND
Time to re-ramp (when V
CC
drops to GND) See Figure 32 0.001 ms
V
CC_TRR_POR50
Time to re-ramp (when V
CC
drops to V
POR_MIN
– 50 mV) See Figure 33 0.001 ms
Level that V
CCP
can glitch down to, but not cause a functional
V
CC_GH
See Figure 34 1.2 V
disruption when V
CCX_GW
= 1 μs
Glitch width that will not cause a functional disruption when
V
CC_GW
See Figure 34 μs
V
CCX_GH
= 0.5 × V
CCx
V
PORF
Voltage trip point of POR on falling V
CC
0.767 1.144 V
V
PORR
Voltage trip point of POR on rising V
CC
1.033 1.428 V
(1) T
A
= –40°C to 85°C (unless otherwise noted)
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