Copyright © 2016 NEXCOM International Co., Ltd. All Rights Reserved.
41
ICES 673 User Manual
Chapter 5: Power Control
C
haPter
5: P
ower
C
ontrol
A. PWR_OK:
Input Power - Sequencing
COM Express
®
input power sequencing requirements are as follows:
Start Sequence:
▪
VCC_RTC must come up at the same time or before VCC_5V_SBY
comes up.
▪
VCC_5V_SBY must come up at the same time or before VCC_12V
comes up.
▪
PWROK must be active at the same time or after VCC_12V comes
up.
Stop Sequence:
▪
PWROK must be inactive at the same time or before VCC_12V
goes down.
▪
VCC_12V must go down at the same time or before VCC_5V_SBY
goes down.
▪
VCC_5V_SBY must go down at the same time or before VCC_RTC
goes down.
Figure 1: Power Sequencing
VCC_RTC
95%
T1
T2
T3
T6
T5
T4
95%
95%
VCC_5V_SBY
VCC_12V
PWROK
T1
VCC_RTC rise to VCC_5V_SBY rise
≥ 0 ms
T2
VCC_5V_SBY rise to VCC_12V rise
≥ 0 ms
T3
VCC_12V rise to PWROK rise
≥ 0 ms
T4
PWROK fall to VCC_12V fall
≥ 0 ms
T5
VCC_12V fall to VCC_5V_SBY fall
≥ 0 ms
T6
VCC_5V_SBY fall to VCC_RTC fall
≥ 0 ms
