
Motorola Internal Use
11
P7389i – Circuit Description
6)
The unit will then follow on as in the sequence below:
On initial power up, all the keypad backlights (
DS500 – DS509
and
DS513
will be
on, they are supported from the signal
ALRT_VCC
(B+ through
Q903
) and switched
by
BKLT_EN
(Whitecap
Pin K3
) through
Q907
.
7)
13 MHz clock
. On Power Up there are 2 different reference clocks produced.
Initially, as soon as power is applied to the
MAGIC DM IC
the
crystal, Y200
,
supported by the
CRYSTAL_BASE
(MAGIC DM
Pin E1
) will emit a 26MHz signal
to the MAGIC DM IC, which will internally be divided by 2 to give our external
13MHz clock. This is then fed out of the MAGIC DM on
Pin J6
(
MAGIC
DM_13MHz
) and distributed to Whitecap
Pin H10
(
CLKIN
), then from Whitecap
Pin B7
to GCAP II
Pin F5
as
GCAP_CLK
. At the same time the 13MHz
Varactor
Diode CR248
is producing an output. This output is controlled in the following way:
The 26MHz from
Y200
is divided down to 200 kHz and fed to a phase comparator
within the MAGIC DM. The 13MHz from
CR248
is also divided down and fed in to
the phase comparator, the difference in phase produces an error voltage that is fed
RESET
SPI_CE
R/W
VCLK
DSC_EN
V1
UPLINK
500
0
50
100
200
300
250
350
150
400
450
EPROM CE
SRAM VB&LB
GCAP
SPI_CE MAGIC
CLK SELECT
DOWNLINK
BFSR 1.7 after RESET, BCKLR at 1.6s