Users Manual & Installation Guide
PV- 5127: Power supply module with UPS
Page 14 of 31
UPS Control
The PV-5127 provides several methods for the CPU to get UPS status information, and to turn off
power. The CPU can get status information through the RS232 and the PC/104 interface, and it can
perform a software-controlled power-off through the ATX PS_ON signal, through an RS232 signal,
and through the PC/104 interface.
PS_ON signal
Two of the ATX functions that are supported in PV-5127 are: +5V STB and PS_ON.
These signals are placed in connector CN10.
In the figure below, the relationship between Mains OK, PS_ON and +5V STB is illustrated.
In this figure, the system temperature and the battery voltage are assumed to be OK. For the full
details involving these conditions, please see the ATX and Softoff state machines section.
1. 5V STB turns on when mains turns on.
2. The CPU can turn itself on and off using PS_ON, and since mains is on, the +5V STB also stays
on.
3. When mains disappears while the CPU is on, it continues running on battery.
4. When the CPU turns itself off while mains isn’t present, everything including +5V STB is
turned off, to conserve battery power. It stays off until mains comes back.
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