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Rev. A
3 Control pow er circuit
The control power (+ 12Vdc and + 5Vdc) comes from the following sources (Figure S-2).
3.1
Start w ithout input AC pow er ( Cold start) :
A “Cold start “is described as follows:
3.1.1
When “ON/ OFF” switch (SW1) is pressed, a positive battery current flows
through SW1 to charge C15.
3.1.2
Q12 base receives a HI pulse and turn on (signal bypass C15 at t= 0, and
charge C15 at t> 0).
3.1.3
When Q12 turns on, the Q12 collector will drop to LOW and turn on Q11
(MPS2907A).
3.1.4
When Q11 turns on, the positive battery voltage via Q12 collector and
establishes a + 12Vdc power supply. The + 12Vdc power supply passes
through U03 (78L05) generating a + 5Vdc logic power supply. And CPU
send HI signal (shutdown) to sustain Q12 on.
3.1.5
Figure W-1 shows the pulse on the C15, i.e. the base signal of Q12 during
the cold start.
3.2
Start w ith input AC pow er ( AC start) :
3.2.1
When we connect UPS to the utility, half-wave rectifier will activate Q12
through D2, ZD1, and Q16.
3.2.2
If “ON/ OFF” switch is pressed, Q11 turns on and establishes a + 12Vdc and
+ 5Vdc power supply similar to “Cold start”.
The SHUTDOWN network, triggered by pin 15 of the CPU, is used to shutdown the UPS on
battery mode. When a battery is in low battery voltage status, the CPU sends a “Low”
signal to turn off Q12. This causes Q11 to be turned off and isolates the control
power from batteries.
Summary of Contents for EP450 series
Page 2: ...Page 1 of 26 Rev A UNINTERRUPTIBLE POWER SYSTEM SPECIFICATION EP450 650 850 Series ...
Page 9: ...Page 8 of 26 Rev A Figure S 2 Control Power Circuit CH1 C15 å GND Figure W 1 Cold Start ...
Page 11: ...Page 10 of 26 Rev A Figure S 3 B Charger Control Circuit ...
Page 18: ...Page 17 of 26 Rev A Figure S 6 CPU Control Circuit ...
Page 26: ...Page 25 of 26 Rev A Figure W 7 Battery Mode Examination Flowchart ...
Page 27: ...Page 26 of 26 Rev A Figure W 8 Line Mode Examination Flowchart ...
