Vicor Autoranging MegaPAC AC-DC Switcher - Manual (Page 17)

UG:106 vicorpower.com Applications Engineering: 800 927.9474 Page 17
Interface Connections (Cont.)
Power Good (J3-3)
The optional Power Good signal on J3-3 is referenced to Signal Ground on J3-1, and
indicates the status of the output voltage (see Figure 8). This signal is asserted a TTL
“1” when the output voltage is above 95% of nominal. It is a TTL “0” when the output
voltage is below 85% of nominal.
If the Trim option is also used, the Power Good trip points DO NOT track with the
trimmed voltage. It is possible to trim the output below the fixed setpoints of the Power
Good circuit and cause a negative Power Good signal.
Power Good Inverted (J3-2)
This is the inverse of the Power Good signal and is referenced to Signal Ground on J3-1.
Signal Ground (J3-1)
Signal Ground on J3-1 is an isolated secondary ground reference for J3 status signals. It
is used to provide a reference point for the Power Good circuitry and is not the same as
Earth Ground on input power connector J9.
Vcc In (J3-4)
The Vcc In on J3-4 is an input that requires +5V either from the J10 Auxiliary Vcc, or
from another source. Input current to this pin is limited by an internal resistor to 3 mA.
If the J10 Auxiliary Vcc is connected to Vcc In on J3-4, then the J10 Signal Ground must
be connected to Signal Ground on J3-1.Earth Ground on input power connector J9.
Figure 8.
Power Good and Vcc
Signal Ground
2
Vcc In
4
J3
10K
2.49K
2N2222
2.49K
1
Power Good
3
Power Good Inverted
ConverterPA C
End of Life - Not Recommended for New Designs