Philips Semiconductors

Product data

PCA9504A

Glue chip 4

2004 May 11

22

SW00593

LATCHED_BACKFEED_CUT

BACKFEED_CUT*

SLP_S5*

T1

T2

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,

X25 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

X200 msec. T1 and T2 are guaranteed by the inherent design of the system and are not controlled by Glue Chip.

SW00594

LATCHED_BACKFEED_CUT

BACKFEED_CUT*

Tpropr

Tr

Tpropf

Tf

SLP_S5*

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.

SW00595

LATCHED_BACKFEED_CUT

BACKFEED_CUT*

T3

Tpropf

SLP_S5*

Tpropr

Tr

Tf

T4

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

µsec to 65 µsec (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

X250 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.