One World Touch OP 1200, Service Manual

Page: 133 / 135

Service Manual version 1008
OP 1200/1500/1700 (PC920 Intel 945G)
8-125

Over voltage Protection
+5Vdc output: +5.7Vdc m6.5Vdc max.
+12Vdc output: +13.3Vdc minimum
+15.6Vdc max.
+3.3Vdc output: +3.7Vdc minimum +4.5Vdc max.

Short Circuit Protection
Output short circuit is defined to be a short circuit load of less than 0.1 ohm.
In the event of an output short circuit condition on +3.3V, +5V or +12V, the power supply will
shut down and latch off. The power supply shall return to normal operation after the short circuit
has been removed and the power switch has been turned off for more than 2 seconds.
In the event of an output short circuit condition on -12V, the power supply will not be latched off.
The power supply shall return to normal operation as soon as the short circuit has been removed
and the power switch has been turned off for more than 2 seconds.

Overload Protection
Overload currents defined as a 10 amp/sec fault current ramp starting from full load, applied to
the +3.3V, +5V output, shall not cause that output to exceed 36 amp before the output voltage
drops below 0.5 volts and is latched off. The 12V output shall not exceed 24 amp under the same
ramp conditions starting at full load before it is latched off.

Power Good Signal
The power good signal is a TTL compatible signal for the purpose of initiating an orderly star-up
procedure under the normal input operating conditions. This signal is asserted (low) until +5Vdc
has reached 4.75 volts during power up. Characteristics;
TTL signal asserted (low state): less than 0.5V while sinking 10mA.
TTL signal asserted (high state): greater than 4.75V while sourcing 500uA.
High state output impedance: less or equal to 1Kohm from output to common.

Output Transient Load Response
+5V and +12V must be within specification for a step change in current as specified below. The
output will be tested one session at a time with all other sections at maximum load. The test
transition will be from IA to IB to IA.
+5Vdc:
IA: 20.0 amp
IB: 15.0 amp
Volts variation: +5V +-5%
Setting time: 10 ms max.
Transient load slew rate is 0.5A/uS
+12Vdc:
IA: 16.0 amp
IB: 12.0 amp
Volts variation: +12V +-5%
Setting time: 10 ms max.
Transient load slew rate is 0.1A/uS
+3.3Vdc:
IA: 16.8 amp
IB: 13.0 amp
Volts variation: +3.3V +-5%
Setting Time: 10 ms max.
Transient load slew rate is 0.1A/uS