May 28, 2008
6871620L01-C
3-22
VOCON Section
3.2.4.1.5 24.576 MHz Reference Generation for MAKO
The 24.576 MHz reference is required by the MAKO IC for the CODEC time base and the SSI clock
generator module internal to the MAKO IC. The clock is generated by crystal oscillator Y1302 and
load capacitors C1316 and C1317.
3.2.4.1.6 SSI Clock and Frame Sync Generator
The MAKO IC generates the SSI clock and frame sync signals for the SAP bus used by the Patriot
IC and encryption module. These signals are generated from the 24.576 MHz reference. The SSI
clock output pin is labeled SSI_CLK, and the frequency is 512 kHz. The SSI frame sync output pin is
SSI_SYNC, and the frequency is 8 kHz. These signals are not active when the MAKO IC comes out
of reset, so they are programmed by the Patriot IC through the SPI bus.
3.2.4.2 ESD Protection Circuitry
See Figure 8-12, “VOCON: Audio, Connector Interface Circuits,” on page 8-13
of the following discussion.
Several components on the VOCON section protect the circuitry from ESD. The CE connector signal
lines have ESD protection components on them since they are exposed. These protection
components include:
• 5.6-V zeners VR1301 on the BAT_STATUS line, 5.6-V zener diode on reset line (UHF), VR1202
and VR1203 on the RS232 and USB data lines
• 6.8V zeners on the OPT_SEL lines, the ONE_WIRE line and the Audio Jack lines
• 12V zeners on the MAKO audio outputs
Spark Gaps are also present on the mainboard layout as a back-up defense mechanism against
ESD.
3.2.4.3 Radio CE Interface Connector Circuitry
See Figure 8-12, “VOCON: Audio, Connector Interface Circuits,” on page 8-13
of the following discussion.
An important circuit in the CE interface connector is the Option Select 2 (OPT_SEL2) line
comparator. The opamp (U1201) is used as a comparator for the option select 2 line. The voltage
divider network of R1227 and R1229 determines the comparator threshold. The remaining
components on the CE interface connector consist of current-limiting serial resistors and noise-
suppressing shunt capacitors.
Summary of Contents for ASTRO XTSTM 4000
Page 1: ...COLOR CHORDS 7 ASTRO XTSTM 4000 Portable Radio Detailed Service Manual ...
Page 2: ......
Page 16: ...May 28 2008 6871620L01 C xiv Commercial Warranty Notes ...
Page 22: ...May 28 2008 6871620L01 C 1 6 Introduction Notes ...
Page 26: ...May 28 2008 6871620L01 C 2 4 Radio Power Notes ...
Page 56: ...May 28 2008 6871620L01 C 3 30 Theory of Operation Notes ...
Page 100: ...May 28 2008 6871620L01 C 6 8 Troubleshooting Waveforms Notes ...
Page 194: ...May 28 2008 6871620L01 C B 2 Motorola Service Centers Notes ...
Page 204: ...May 28 2008 6871620L01 C Glossary 10 Glossary Notes ...
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