User's Manual

Model 1150A DVOR
Rev. - November, 2008
This document contains proprietary information and such information may not be disclosed
to others for any purposes without written permission from SELEX Sistemi Integrati Inc.
2-51
+12Vdc
P2
60 Pin DIN41612
Hybrid Connector
Ground
+48Vdc
From Control Backplane
+5Vdc
-12Vdc
~TEST
P1
96 Pin DIN41612
Connector
Fuse
Ground
+28Vdc
~LVPS_OK
VCO_EN
VCO_PWR
DC-DC Converter
Filter
Power OK Window
Comparators
Power OK
LED
Filter
Load
Resistors
DC-DC Converter
Figure 2-19 LVPS CCA Block Diagram
2.3.2.16.2
Low Voltage Power Supply (LVPS) CCA Detailed Circuit Theory
Refer to Figure 11-15. System +48VDC enters the CCA via connector P2:C26, is routed to fuse F1 and measurable
on test point TP1. Fuse F1 provides over-current protection to DC-DC converter U1, which generates the +28VDC
supply. The +28VDC output is measurable on test point TP3 and exits via connector P1:C30.
Two types of over-voltage protection are utilized for DC-DC converter U1. Silicon-Controlled-Rectifier (SCR) Q1
in conjunction with CR8, CR9, R8, R4, and C1 will activate and open fuse F1 if the output voltage exceeds
approximately +31.2VDC. Zener diode CR10 provides redundant over-voltage protection.
Capacitors C4 and C14 provide input filtering to the PS1 DC-DC converter, which generates the +5VDC, +12VDC,
and -12VDC supplies. The +5VDC output is measurable on test point TP2 and exits via connector P1:C1. Resistors
R2, R7, R10-R15, R36, and R37 provide a constant minimum load on the +5VDC output, ensuring PS1output
regulation.
The +12VDC output is filtered by C11, L4, and C13. The +12VDC output is measurable at test point TP9 and exits
via connector P1:B31.
The -12VDC output is filtered by C10, L3, and C12. The -12VDC output is measurable at test point TP8 and exits
via connector P1:C32.