SX-200 General Information Guide
62
Revision A
50003510
Power Supply
All power for the SFT unit is provided from the -48 Vbat source on the system. A source of -12
V powers the electronic circuitry on the card. This supply is derived from the -48 V input and
powers all the SFT circuitry except the transfer relays. The relays are powered by a
transistor-regulated -41V source, also derived from the -48 Vbat input. Thus, in the event of
Vbat varying between the standard -42.5 V to -56.5 V, the current drain remains constant.
Transfer Relays
Each circuit in the SFT uses a four form C relay to transfer between normal and SFT modes
of operation.
Loop Detector
When a transfer relay enters SFT mode, the loop detector connects in series with the loop
between the extension and CO trunk facility. This circuit prevents the extension from returning
to normal operating mode before an SFT mode call is completed. When the SFT mode call is
completed, the extension is returned to normal operating mode.
SFT Control Leads
The transfer control sensor on the SFT senses a loop closure across the SFT and SFT return
(SFTR) leads. When a loop closure is sensed, the power to the relays is removed, the relays
are released, and all circuits enter the transferred state.
Power Consumption
The total current drain for the SFT is typically 80 mA.
Power Dissipation (watts)
Power Supply
TYP. (Watts)
TYP+20%
-48Vbat
3.18
3.81
@Vbat=-56 V
3.71
4.45
Summary of Contents for SX-2000 EL
Page 1: ...GENERAL INFORMATION GUIDE LIGHTWARE 19 RELEASE 3 1 ...
Page 14: ...xiv Revision A 50003510 SX 200 General Information Guide ...
Page 34: ...SX 200 General Information Guide 20 Revision A 50003510 ...
Page 61: ...Configuration 50003510 Revision A 47 SX 200 ML Configuration Example ...
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Page 257: ...Glossary of Terms 50003510 Revision A 243 NOTES ...