Motorola 38C V100 Service Manual page 21

Level 3 Service Manual
6881036B20
13 MHz clock. Initially, upon power being applied to the Magic IC, crystal Y200
(supported by CRYSTAL_BASE (Magic IC Pin E1)) emits a 26 MHz signal to the
Magic IC. The 26 MHz signal is internally divided by two, to produce the external
13MHz clock. The 13 MHz clock is then fed out of the Magic IC on Pin J6 Magic
IC_13MHz and distributed to Whitecap IC Pin H10 CLKIN, then from Whitecap
IC Pin B7 to GCAP II Pin F5 as GCAP_CLK. At the same time, 13 MHz varactor
Diode CR248 is producing an output. This output is controlled in the following way:
The 26 MHz from Y200 is divided down to 200 kHz and fed to a phase comparator
within the Magic IC. The 13 MHz from CR248 is also divided down and fed to the
phase comparator, the difference in phase producing an error voltage that is fed
onto the cathode of varactor CR248 to stabilize the 13 MHz clock. Once the software
is running and the logic side of the board has successfully powered-up, the
CLK_SELECT signal from Whitecap IC Pin A1 is fed to Magic IC Pin G6. This in
turn switches the Multiplexer from the output of Y200 to the output of CR248 (see
Figure 9).
Phase 1
Phase 2
Y200
26MHz
F
F
2
Figure 9. 13 MHz Clock Block Diagram
SIM Card Interface
The SIM interface is part of the Whitecap IC U800 and supports both synchronous
(prepay card) and asynchronous serial data transmission. The SIM card is interro-
gated on power-up. VSIM1 (SIM_VCC) defaults to 3V but, if a 5V card is present
the SIM card is powered-down and VSIM1 reprogrammed to 5V. SIM inputs and
outputs are level-shifted within GCAP II U900 to 3V. These signals are:
• Reset. Whitecap IC Pin E9 RST0 to GCAP II Pin K7 LS1_IN_TG1A. This sig-
nal is level-shifted to the required voltage and fed to SIM contacts J803 Pin 2
from Pin J7 LS1_OUT_TG1A.
• Clock. This is a 3.25MHz signal from Whitecap IC Pin E9 CLK0 [Pin E7] to
GCAP II Pin G6 LS2_IN. This signal is level-shifted to the required voltage
and fed out to SIM Contacts J803 Pin 1 from Pin F6 LS2_OUT.
• SIM I/O. Data transmission to and from SIM card.
• TX: From SIM card contact SIM I/O J803 Pin 6 through to GCAP II Pin
J8 SIM I/O. Level-shifted to desired voltage and out through Pin K10
MOTOROLA CONFIDENTIAL - PROPRIETARY
November 20, 2000
PLL
200 kHz
F
Pha s e
Det ector
F
130
Multiplexe r
13MHz Output
to White cap
Circuit Description
Error Voltage
F
CR248
F
65
13 MHz
MAGIC IC
U913
000721-O
17