User's Manual

Model 1150A DVOR
2-36 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.
2.3.2.10.1 Facilities CCA Detailed Theory
Refer to Figure 11-18. System1 and System2 +48V power from connector P2-25 and P2-26 are scaled down by
resistor networks RN1 and RN2 for input to the A-D converter as well as diode-OR’D by CR1 and CR2 to create the
facilities +48V supply. This supply (also named LED_PWR) lights the CR24 PWR_OK LED when transistor Q1 is
turned on under software control by U22-19; indicating all monitored power supplies are within range.
The facilities +48V is fused by F1 and regulated by regulator U1, L1, diode CR3, and C2 to create +5DIG. Zener
CR36, R68, and SCR Q3 protect downstream circuitry in the event of an over-voltage event by opening fuse F1.
Zener CR37 will short to ground and protect the downstream circuitry if the SCR/Fuse-blowing circuitry fails for
any reason.
The +5DIG supply is further filtered and regulated by regulator U2 and capacitors C3 and C4 to create the +3.3V
supply. The +5DIG supply is also input to DC-DC converter PS1 to create -15V and +15V supplies. The -15V is
filtered and regulated by L2, C8, U3, and C9 to realize -12ANA and by C7, U4, and C10 for -12DIG. The +15V
output is filtered and regulated by L3, C12, U5, and C13 to realize +12ANA and by C11, U6, and C14 for +12DIG.
The facilities +48V also feeds fuse F2 and regulator U7. Switching regulator U7, C15, L4, CR4, CR5, R10, C17,
and R11 combine to convert 48 volts to +24V. Zener CR38, R69, and SCR Q4 protect downstream circuitry in the
event of an over-voltage event by opening fuse F2. Zener CR39 will short to ground and protect the downstream
circuitry if the SCR/Fuse-blowing circuitry fails for any reason.
The ~MRESET signal enters via P1-B16, is filtered by FL1/C19, diode-isolated by CR6, and resets U8 when active.
U8 outputs ~RESET, which clears the outputs of on-board latches U22, U23, and U38. ~RESET is also asserted by
U8 if the +3.3V supply drops too low after R14 and before U8-2.
The ~TEST signal enters on P2-B8 and will light on-board indicators CR13-CR21, and CR24 when active. The
~TEST signal will also cause audio to be emitted from speaker SPK1 when active. The ~TEST signal is transient-
voltage-suppression (TVS) protected by CR40.
Asynchronous data and address busses provided by the RMS CCA enter via connector P2 and are pulled-up by
resistor networks RN12 and RN13. The address bus is decoded into sixteen segments by U9 and U10; ten of which
are used by the Facilities CCA.
The ten spare analog inputs (SPARE_ANA1 through SPARE_ANA10) and four spare digital inputs (SPARE_DIN1
through SPARE_DIN4) enter via connector P1 and are terminated to ground by resistor network RN3 before
connection to analog multiplexers U20 and U21.
The DIALUP/~EXT control signal enters via P1-C26. When this signal is high, buffer/converter U11 is enabled and
RMM_TX_232, RMM_RX_232, RMM_DTR_232, and RMM_DCD_232 signals will pass through U11 to Dial-up
modem U12 to become ~DU_TXDD, ~DU_RXDD, ~DU_DTRD, and ~DU_DCDD. Components R19, R18, CR9,
R20, R17, and CR10 convert +5V signal levels to +3.3V between U11 and U12. Dial-up modem U12 lights
indicator CR13 when a RING is received. Dial-up modem U12 also lights indicators CR14 through CR17 when
serial data and control signals are active.
The tip and ring signals from Dial-up modem U12 are TVS-protected and filtered by CR7, FL2 and FL3 before
exiting connector P2-B14 and P2-B15. Audio from U12-64 is scaled by R29 and R31 before audio header JP1-1.
The DED/~RADIO control signal enters via P1-C25. When this signal is high, buffer/converter U13 is enabled and
RADIO_TX_232, RADIO _RX_232, RADIO _DTR_232, and RADIO _DCD_232 signals will pass through U13 to
Dedicated modem U14 to become ~DED_TXDD, ~DED_RXD, ~DED_DTRD, and ~DED_DCD. Components
R22, R24, CR11, R23, R25, and CR12 convert +5V signal levels to +3.3V between U13 and U14. Dedicated
modem U14 lights indicators CR18 through CR21 when serial data and control signals are active.