F800 CIRCUIT DESCRIPTION
24 (25)
Uppgjord (även faktaansvarig om annan) -
Prepared (also subject responsible if other)
Nr -
No.
KL/ECS/S/LT Magnus Lindahl ECS/S/LT-96:5044
Dokansv/Godk -
Doc respons/Approved
Kontr -
Checked
Datum -
Date
Rev File
KI/ECS/S/LTC 1996-06-06 A
965044.DOC
Power supply
DC power is connected to the processor board from the radio board. The voltage is
filtered and fused on the radio board. This voltage is always present as long as the
F800 is connected to external DC. The voltage is used as DC source for the 5 VB
regulator, Z27. The 5VB provides voltage to the line interface via P405:13.
12V
5VB
5V
Reset
Z28
Z27
12V
U=5V
U=5V
FIG Q: Internal DC circuits
The 12V is also connected to regulator Z28 which provides 5V to internal circuits. The
regulator includes a power on reset. The reset line of the processor is kept low until
the output voltage exceeds 4,8V.
Bias voltages, 1,8VT and 1,8VR, for the AF circuits are derived from 5V.
Both 5 V, 5 VA and 12 VSW are connected to the option board.
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