pca9504a NXP Semiconductors, pca9504a Datasheet - Page 22

• Manufacturer Part Number: pca9504a
• Description: Glue Chip 4
• Manufacturer: NXP Semiconductors

Philips Semiconductors
Product data
Glue chip 4
PCA9504A
T1
BACKFEED_CUT*
T2
SLP_S5*
LATCHED_BACKFEED_CUT
SW00593
Figure 14. Power up signal sequencing
Power up signal sequencing is shown in Figure 14. BACKFEED_CUT* is following the power rail up to its final value.
LATCHED_BACKFEED_CUT should stay LOW, never turning on. SLP_S5* goes to its HIGH value when the power rails have stabilized,
25 msec after power on. BACKFEED_CUT* is pulled LOW a period T1 after SLP_S5* goes HIGH. T1 can be as short as 1msec. Typical
measured values are
200 msec. T1 and T2 are guaranteed by the inherent design of the system and are not controlled by Glue Chip.
SLP_S5*
Tpropr
Tpropf
BACKFEED_CUT*
Tf
Tr
LATCHED_BACKFEED_CUT
SW00594
Figure 15. 1st sequence timing
The first possible sequence is with SLP_S5*staying HIGH and BACKFEED_CUT* transitioning from LOW to HIGH, remaining HIGH for an
undetermined period and then going back to LOW and the system is back at the end of the power-up sequence. The power-up sequence is
shown in Figure 15. During these BACKFEED_CUT* transitions, the propagation delays, rise and fall times, and going into regulation times
LATCHED_BACKFEED_CUT are as described in Figure 16. The first sequence starts can start at the end of the power-up sequence at any time.
T3
T4
BACKFEED_CUT*
SLP_S5*
Tpropr
Tpropf
LATCHED_BACKFEED_CUT
Tr
Tf
SW00595
Figure 16. 2nd sequence timing
Signal sequencing for the second possible sequence is shown in Figure 16. BACKFEED_CUT* goes from LOW to HIGH and SLP_S5* goes
from HIGH to LOW, 30 sec to 65 sec (T3) later. LATCHED_BACKFEED_CUT goes HIGH when BACKFEED_CUT* goes HIGH and then
LATCHED_BACKFEED_CUT returns to LOW when SLP_S5* goes LOW. BACKFEED_CUT* stays HIGH and SLP_S5* stays LOW for an
indeterminate time and then SLP_S5* will go HIGH. A minimum of 1msec (T4) later, BACKFEED_CUT* will go LOW and the system is back at
the end of the power-up sequence. Typical measured values of T4 are
250 msec. During all transitions, the propagation delays, rise and fall
times, and going into regulation times for LATCHED_BACKFEED_CUT are as described in Figure 16. The first sequence starts can start at the
end of the power-up sequence at any time.
2004 May 11
22