Instruction manual

1-12 / Introduction ControlWaveLP
The power supply operates from 10.0 to 20V or 20.7 to 30V (dc). The nominal settings for
the 12V supply are ON state above 10.45V, and OFF state below 10.0V. The nominal
settings for the 24V supply are ON state above 22V, and OFF state below 20.7V. A power
MOSFET is utilized to switch the input power to the power supply circuitry. A mechanical
switch (SW1) will drive the gate of the MOSFET. The three isolated supplies generated by
the power supply are rated for a maximum current of 1A @ +5V, 200mA @ +12V and 200mA
@ -12V. + and - 12V supplies are regulated by linear regulators while the +5V (VCC) supply
is regulated by a PWM circuit.
Figure 1-6 - Top View of PSSB Board (not all components shown)
The sequencer monitors the incoming power and the isolated supply voltages. The low
limits for the incoming power and isolated supplies are 10.25 for a 12V system or 21.3V, for
a 24V system and, 4.75V, 11.4V and -11.4V for the regulated +5V (VCC), +12V and -12V
supplies respectively. The sequencer circuit also generates MC and PFIN. These timed
signals allow the CPU to save status if the incoming power or the isolated supplies fall
below their respective low limits. Note: CPU status cannot be guaranteed if the +5V (VCC)
supply shorts or abruptly falls out of spec. MC and PFIN will remain active until 100msec
after the input power or isolated supplies are above their low limits. When either MC or
WDOGB are active, the watchdog relay or power MOSFET will be OFF. WDOGB is a signal
generated by the CPU.
The low input power detection circuitry and sequencer are on the primary side of the power
supply and drive two optocouplers. The remainder of the low voltage detection circuitry is