Philips ISP1520 Fig 4. External clock with respect to power-on reset., Fig 3. Power-on reset timing.

Philips Semiconductors ISP1520
Hi-Speed USB hub controller
Product data Rev. 03 — 24 November 2004 11 of 51
9397 750 13701 © Koninklijke Philips Electronics N.V. 2004. All rights reserved.
The triggering voltage of the POR circuit is 2.03 V nominal. A POR is automatically
generated when VCC goes below the trigger voltage for a duration longer than 1 µs.
At t1: clock is running and available.
Fig 3. Power-on reset timing.
Stable external clock is to be available at A.
Fig 4. External clock with respect to power-on reset.
004aaa388
t1
VCC
2.03 V
0 V
≤ 683 µs
POR
POR
EXTERNAL CLOCK
A
004aaa365