Motorola SSETM 5000 service manual Receive Audio Path, Gcap II IC U501

Theory of Operation: VOCON Board 2-33

INTERNAL MIC

Bias (R531,

R533, C519, C521) and Input

(R540, C522)

EXTERNAL MIC

Bias (R563,

R565, C547, C548) and Input

(R566, C549)

TP214

R555	EEPOT U509
	0 - 50K, 256 taps
		MIC_OUT
MICIN	MIC PREAMP		GCAP II IC U501
_NEG	A3
	Gain =
	-14dB to 16dB
			PGA		CODEC A/D		HP FILTER
		MUX	-7 to +8dB
			in 1dB steps		13-bit		cutoff = 200HZ
			Set at 6dB
AUX_MIC	MIC PREAMP
_NEG	A5
	Gain =						LP FILTER
	-14dB to 16dB
							cutoff = 3.5KHZ
		AUX_OUT
R561	EEPOT U509	GCAP_CE, SCKB		CODEC_TX		CODEC_FSYNC
	0 - 50K, 256 taps	SPI_MISOB	4
		SPI_MOSIB				CODEC_DCLK
	4	Patriot GPIO	Patriot SPIB		Patriot SAP/BBP		Flipper
		PB4, PB5,
							U301
	EEPOT_CS_EXT*	PB6, PB7
	EEPOT_CS*				3	TX_SSI_FSYNC
	EEPOT_U_D*
	EEPOT_INC*					TX_SSI_CLK
						TX_DATA
					RF D/A
					U203
					(On RF Board)
							MAEPF-27418-A

Figure 2-11. VOCON Transmit Audio Path

2.5.5.2 Receive Audio Path

Refer to Figure 2-12. The receive audio data comes from the Abacus III IC U500 through the RF interface connector P201 pin 12 (RX_DATA) to the dual-core processor SRDB pin. The DSP decodes the data and sends it out through the CODEC_RX line to the GCAP II IC RX pin. The CODEC filters and converts the digital data into an analog audio signal, which, in turn, is sent to a programmable gain amplifier. The dual-core processor programs a multiplexer to route the audio signal to the A4 amplifier, which has a fixed gain of 3.5 dB. The output of the A4 amplifier is pin

EXTOUT.

From the EXTOUT pin, the audio signal goes through the pre-amplifier U502 and then to the audio power amplifier U503, which together provide approximately 30 dB of gain. The dual-core processor selects whether the amplified audio is routed to the internal speaker or the external speaker.

6881094C12-A November 11, 2004