Motorola ASTRO XTSTM 4000 Detailed Service Manual page 46

3-20
The MAKO contains two internal audio power amplifiers for internal and external speaker routing and
the outputs are available at pins INT_SPKR_P and INT_SPKR_M (internal speaker) and
EXT_SPKR_P and EXT_SPKR_M (external speaker).
audio routings to the various transducers. The audio routing selection is controlled by the Patriot IC.
3.2.3.2 5 V Regulator U1101
The 5 V regulator, U1101, uses UNSW_B+ as its input voltage. This regulator supplies 5Vdc to the
keypad circuitry, the radio ON/OFF circuitry and the display backlight control circuitry.
3.2.3.3 Audio Switch U20
The audio switch U20 is a single-pole, double-throw analog switch that switches amplified audio from
the MAKO external speaker terminals (EXT_SPKR_P and EXT_SPKR_M) to the earpiece (on the
flip assembly) or the single ended audio gain stage for the 2.5mm audio jack earpiece. The U20 is
supplied from VCC5.
3.2.3.4 Single-Ended Audio Gain Stage U9904
U9904 is the single-ended audio gain stage for the 2.5mm audio jack earpiece. It consists of a non-
inverting operational amplifier and DC biasing circuitry. One of the outputs of the audio switch (U20)
is channelled to U9904.
3.2.4 Accessory and CE Interface Connector Support
The accessory and CE interface connector support section consists of the following:
• MAKO IC U1304
• ESD protection circuitry
• CE connector interface circuitry
The MAKO IC contains a RS232 and USB transceiver, switching logic between RS232 and boot data
path, One-Wire side connector support, and several supporting circuitry. The MAKO IC is
programmed by the Patriot IC.
ESD protection devices include zener diodes and low-capacitance ESD suppressors.
CE interface connector circuitry includes current-limiting resistors and noise-suppressing shunt
capacitors.
3.2.4.1 MAKO IC U1304
See Figure 8-14, "VOCON: DC Power, Clocks and ON/OFF Circuit," on page 8-15
details of the following discussion.
The MAKO IC U1304 also contains the circuitry and blocks to support radio accessories and test/
programming service aids. The block supports many functions including radio CE connector
interface, bi-directional logic level translation, boot data path control, USB transceiver and One Wire
option detect support.
May 28, 2008
Theory of Operation: VOCON Section
Section 3.2.5.2 on page 3-27 details the
for schematic
6871620L01-C