Motorola SSETM 5000 - Manual (Page 48)

November 11, 2004 6881094C12-A
2-26 Theory of Operation: VOCON Board
2.5.2.2.6 EEPOT U509
The EEPOT is a digitally programmable potentiometer with 256 taps and a total resistance of 50
Kohms. This 10-pin package contains two independent potentiometers, one for each microphone
line. The EEPOT resistance values are programmed by the dual-core processor GPIOs
EEPOT_INC* (U509 pin 9) and EEPOT_U_D* (U509 pin 2). The EEPOT_INC* signal increments the
resistance value up or down, which depends on the EEPOT_U_D* signal. The EEPOT_CS* line
(U509 pin 10) is asserted when the internal microphone gain is being changed. Similarly, the
EEPOT_CS_EST* (U509 pin 1) is asserted for external microphone gain changes. The EEPOT is
supplied with voltage from the GCAP II V2 regulator.
2.5.2.3 Interface Support
The interface support section consists of the following:
• Digital-support IC U301
• ESD protection circuitry
• Universal connector interface circuitry
The digital-support IC contains a USB transceiver, switching logic between RS232 and boot data
path, One- Wire side connector support, and several clock generators. The digital-support IC is
programmed by the dual-core processor.
ESD protection devices include zener diodes and low-capacitance ESD suppressors.
Side connector interface circuitry includes current-limiting resistors and noise-suppressing shunt
capacitors.
2.5.2.3.1 Digital-Support IC U301
NOTE: See Figure 12-14. NCN6186_ VOCON Flipper Circuit on page 12-20 .
The digital-support IC U301 is an application-specific integrated circuit (ASIC) device designed for
the SSE 5000. It is contained in a 64-pin µBGA package with 0.8 mm pitch solder balls. The digital-
support IC is supplied with 5 V and the processor’s GPIO voltage. It is supplied with a 16.8 MHz
clock from the transceiver board. Using this clock, the digital-support IC generates a 13 MHz clock
for the GCAP II IC. Additionally, the digital-support IC uses a crystal to generate the 32 kHz clock
used by the dual-core processor and GCAP II IC.
The digital-support IC supports many functions, including the radio’s universal (accessory) side
connector interface, One-Wire option detect support, watchdog timer, and 32 kHz oscillator with
CMOS output. It also monitors the position of the on/off switch and controls the shutdown of the
regulators on the GCAP II IC.
The digital-support IC is programmable by the dual-core processor through the SPI bus.
Table 2-9. Audio PA Status
AUDIO_PA_EN AUDIO_MODE_SEL Audio PA Status MODE Voltage
0 0 Standby V_Mode > 7 V
0 1 Mute 1.5 V < V_Mode < 6 V
1 0 On V_Mode < 0.5 V
1 1 On V_Mode < 0.5 V