Motorola SSETM 5000 Radio Power-Up/Power-Down Sequence, Theory of Operation Vocon Board

2-34	Theory of Operation: VOCON Board
	GCAP II IC U501

		LP FILTER			HP FILTER		GCAP CODEC
	cutoff = 3.5KHZ			cutoff = 200HZ			13-bit D/A
			CODEC_DCLK				GCAP_CE, SCKB
						4	SPI_MOSIB
							SPI_MISOB
CODEC_FSYNC					CODEC_RX

				TP212
	PGA	GCAP A4
-35 to 0dB					TP2123
		Gain = 1.5
in 5dB steps		(3.5dB)
Default 0dB
			EXTOUT			External
						Speaker

Flipper		PATRIOT		PATRIOT	PATRIOT
U301		SAP/BBP		SPI B	GPIO
			RX_SSI_FSYNC
	3		RX_SSI_CLK
			RX_SSI_DATA
		ABACUS III
		U500
		(On RF Board)

EXT PRE-AMP

U502

Gain set by

R537 and R551

Audio PA Enable

Control circuits

1/2 Q505

	AUDIO PA U503
	Gain set by R550,
	R554, R549, and			28 Ohm
	R553			Internal
	MODE SELECT			Speaker
Audio PA Mute		Int/Ext SPKR SEL
	Control		Control circuits
Q506,R564,R559			1/2 Q505, R558

AUDIO_PA_ENABLE AUDIO_MODE_SEL EXT_SPKR_SEL

Audio_PA_Enable	Audio_Mode_Sel	Audio PA Status	Mode (V)	PA Status
0	0	Audio Off	1.5V <V_mode<6V	Mute
0	1	Mute	<0.5V	Audio On
1	0	Audio On	>7V	Audio Off
1	1	Audio On

Figure 2-12. VOCON Receive Audio Path

Select (V)	Internal Speaker
B+ (7.5V)	Internal Speaker
<0.5V	External Speaker

MAEPF-27417-A

2.5.6Radio Power-Up/Power-Down Sequence

The radio power-up sequence begins when the user closes the radio On/Off switch on the control top, placing 7.5 Vdc on the B+SENSE line. This voltage enables the pass element Q501 and Q502, enabling SW_B+ and GCAP_B+.

When the GCAP II IC U501 detects a low-to-high voltage transition on GCAP_B+, it turns on and enables voltage supplies VSW1, VSW2, V2 and Vref. As soon as these voltages come up, the

1.55V regulator ramps up (only on the VOCON board), and the digital-support IC U301 drives the WDI line high to enable VCC5 from regulator U505 and to maintain the GCAP II IC in the ON state. If WDI remains low, the GCAP II IC turns off 50 ms after turning on.

The radio power-down sequence begins by opening the radio On/Off switch, which removes the B+SENSE signal from the VOCON board. This does not immediately remove power because the GCAP II IC has control of Q502 through Vref, and U301 through WDI maintains the GCAP II IC in an active state. Both the MCU and digital-support IC monitor B+SENSE. After B+SENSE is removed, the digital-support IC waits 125 ms. before releasing WDI to allow for software cleanup; however, the software has the ability to prolong this time if it was necessary to complete its operations. When WDI is released, the GCAP II IC shuts down its supplies and the rest of the radio through Q501.

November 11, 2004 6881094C12-A