Vicor DC MegaPAC DC-DC Switcher - Manual (Page 10)

Pg. 10 Vicor 800-735-6200 Mission Power Solutions (760) 631-6846 (phone) or (760) 631-6972 (fax) Rev. 3/04
DC MegaPAC Operator’s Manual
78M05
Auxiliary Vcc 9
0.1 µF
Signal Ground
J10
10
+5V/300 mA
Input Power Fail (J10-19)
The Input Power Fail signal on pin J10-19 is the inverse of the Input Power OK signal on J10-18, and goes to a TTL "0"
when the input DC power is OK. It is capable of sinking 20 mA maximum.
Overtemperature Warning (J10-3)
J10-3 is a signal that asserts a TTL level "1" if the air temperature exceeds the following factory set levels. The warning trip
point is 65°C to 76°C, typically, and recovery point is 60°C to 71°C, typically.
Overtemperature Shutdown
If the inlet ambient air temperature exceeds the following factory set levels, the outputs are disabled. The shutdown trip
point is 70°C to 81°C, typically, and recovery point is 40°C to 48°C, typically.
Analog Temperature Monitor (10-4)
This signal on J10-4, referenced to Signal Ground, provides an analog DC voltage output between 0V and 10V that repre-
sents the air temperature of 0°C to 100°C, respectively, inside the power supply. The inlet air temperataure is monitored
close to the fan.
Gate IN/Gate OUT (J10-13, 25)
The Gate IN and Gate OUT signals are used for paralleling DC MegaPACs for power expansion. The Gate OUT signal,
J10-25, of the driver DC MegaPAC should be connected to the Gate IN, J10-13, of the Booster DC MegaPAC; J10 signal
ground of the driver DC MegaPAC also needs to be connected to J10 signal ground of the booster DC MegaPAC.
The driver DC MegaPAC (ModuPAC, slot #8) generates the Gate OUT signal and sends it to the booster DC MegaPAC
(ModuPAC, slot #1). Vicor's zero-current-switching booster technology provides for accurate, dynamic power sharing with-
in arrays, without the need for trimming, module "matching" or external components.
Auxiliary Vcc +5V/0.3A (J10-16, 17)
The Vcc on J10-16 and J10-17 is an auxiliary 5V regulated power source (see Figure 10 and Connector Pin Identification
on page 14). It is +5 Vdc (± 5%) with respect to Signal Ground, and can supply 300 mA maximum. It is short-circuit-proof,
but if shorted, all outputs will shut down through the Enable/Disable circuitry. The Auxiliary Vcc typically powers user cir-
cuitry or is used with the Power Good circuitry to provide a pull-up reference for the outputs of the DC Power Good circuit
on a ModuPAC. If used for this purpose, a Signal Ground on J10 must also be connected to the J3-1 Signal Ground pin of
the ModuPAC.
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 volt-
age. 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.
78M05
Auxiliary Vcc 16
0.1 µF
Signal Ground
J10
15
+5V/300 mA
Auxiliary Vcc 17
Figure 10. Auxiliary Vcc