Two-Way Radio User Manual

4-1
November 1999
Part No. 001-7780-500
CIRCUIT DESCRIPTION
SECTION 4 CIRCUIT DESCRIPTION
127($EORFNGLDJUDPRIWKH5)DQGORJLFXQLWVLV
ORFDWHGRQSDJH
4.1 POWER SWITCHING AND REGULATION
4.1.1 POWER SWITCHING
8QVZLWFKHGEDWWHU\Y ROWDJHLVDSSOLHGWRWKH 
SRZHUDPSOLILHUPR GXOHDQGSRZHUFRQWUROFLUFXLWLQ
WKH5)XQLW2WKHUZLVHDOOSRZHULVVZLWFKHGE\
3FKDQQHO026)(7V4DQG4LQWKHORJLF
XQLW7KH/9&&VXSSO\LVSURGXFHGE\ 4DQGWKH
9&&VXSSO\LVSURGXFHGE\4:KHQWKHR QRII
VZLWFKLVWXUQHGRQWKHRXWSXWRIVZ LWFKLQJWUDQVLVWR U
4JRHVORZZKLFKWXUQV4DQG4RQ7KLV
DSSOLHVVZLWFKHGYROWVWR YROWUHJXODW RUV,&
DQG,&WKHDXGLRDPSOLILHUVWD JHVDQGRWKHUSDUWV
RIWKHWUDQVFHLYHU
:KHQWKHSRZHUVZLWFKLVWXUQH GRIIWKHEDVHRI
4LVSXOOHGORZE\5ZKLFKWXUQV4RIIDQG
WKHFROOHFWRUJRHVKL JK+RZHYHUEHFDXVHRIGLRGH
'4DQG4GRQRWWXUQRIIXQWLO&
FKDUJHVWKURXJK57KLVSURYLGHVDVOLJ KWWXUQRII
GHOD\ WRJLYHWKHPLFURSURFHVVRUWLPHWRWDNHRYHU
SRZHURIIFRQWURO7KHPLFURSURFHVVRULPPHGLDWHO\
GHWHFWVSRZHUWXUQRII E\PRQLWRUL QJWKH2))5(4,
VLJQDORQSLQ,WWKHQFKDQJHVWKH2))5(4R XWSXW
RQSLQWRDKLJKOHYHOZKLFKWXUQV4DJD LQRQ
XQWLOFXUUHQWVHWWLQJVKDYHEHH QVDYHGWRPHPRU\ DQG
RWKHUUHTXLUHGSRZHUGRZQIXQFW LRQVKDYHEHHQ
SHUIRUPHG
4.1.2 5-VOLT REGULATORS (IC401, IC402)
5HJXODWRU,&LQWKHORJLFXQLW SURYLGHVWKH
/9ORJLFVXSSO\DQGUHJXODWRU,&SURY LGHV
WKH9VXSSO\7KH9VXSSO\LVLQWXUQVZLWFKHG
E\44WRSURYLGHWKH5979DQG6
VXSSOLHV7KHVHWUDQVLVWRUVD UHFRQWUROOHGE\VLJQD OV
IURPWKHPLFURSURF HVVRU
7KHORZEDWWHU\GHWH FWVLJQDOLVSURYLGHGE\D 
YROWDJHGLYLGHUIRUP HGE\5DQG57KHVH
UHVLVWRUVGLYLGHGRZQWKH 99FFVXSSO\WRSURGXFH
WKH%$7, 1VLJQDOWKDW LVDSSOLHGWRSLQRIWKH
PLFURSURFHVVRU
4.2 SYNTHESIZER DESCRIPTION
4.2.1 INTRODUCTION
7KHV\QWKHVL]HURXWSXWVL JQDOLVSURGXFHGE\D
9&29ROWDJH&RQWU ROOHG2VFLOODWRU LQWKH5)XQLW
7KH9&2IUHTXHQF\LVFRQWUR OOHGE\D'&YROWDJH
SURGXFHGE\WKHSKDVHGHWHFW RULQV\QWKHVL]HUFKLS
,&7KHSKDVHGHWHFWRUVHQVH VWKHSKDVHDQG
IUHTXHQF\RIWKHWZR LQSXWVLJQDOV2QHVLJQDOLVWKH
UHIHUHQFHIUHTXHQF\ IURP7&;2;DQGWKHRWKHULV
IURPWKH9&2,IWKHVHVLJ QDOVDUHQRWWKHVDPH
IUHTXHQF\WKHSKDVHGHWHFWRUFKDQJHVWKH9&2
FRQWUROYROWDJHZKLFKF KDQJHVWKH9&2IUHTXHQF\
XQWLOERWKVLJQDOVDUHV\QFKURQL] HG7KH9&2LVWKHQ
³ORFNHG´RQIUHTXHQF\
&KDQQHOVDUHVHOHFWHGE\ SURJUDPPLQJWKH
FRXQWHUVLQ,&WRGLYLGHE\GLIIHUHQWQXP EHUV7KLV
SURJUDPPLQJGDWDFRPHVIURPWKHPLFURSURFHVVRURQ
WKHORJLFERDUG7KHIUHTXHQF\VWD ELOLW\RIWKHV\QW KH
VL]HULQERWKWKHUHFHLYHD QGWUDQVPLWPRGHVLVGHWHU
PLQHGE\WKHVWDELOLW\R I7&;2;7KHVWDELOLW\R I
WKLVGHYLFHLV330IURP±WR )±WR
&7KH9&2RXWSXWVLJQDOLVEXIIHUHGDQGWKHQ
IHGWRWKHUHFHLYHUDVW KHILUVWLQMHFWLRQVLJQDODQGWR
WKHWUDQVPLWWHUDVWKHW UDQVPLWVLJQDO
4.2.2 VCO (IC3), BUFFERS (Q10-Q12)
6XSSO\YROWDJHWR9&2,&LVIURP&39UHJX
ODWRU,&DQGDFWLYHILOWHU4RQWKH,)ERDUG4
IXQFWLRQVDVDFDSDFLWDQFHPXOWLSOLHUWRSURYLGH
ILOWHULQJ RIWKHYROWVXSSO\WRWKH 9&25DQG]HQHU
GLRGH'SURYLGHELDVDQG&SURYLGHVWKHFDSDFL
WDQFHWKDWLVPXOWLSOLHG,IDQRLVHSXOVHRURWKHU
YROWDJHFKDQJHDSSHDUVRQWKHFROOHFWRUWKHEDVH
YROWDJHGRHVQRWFKDQJHEHFDXVHRI&DQG'7KHUH
IRUHLWGRHVQRWDSSHDURQWKHHPLWWHU
7KH9&2FRQWUROYROWDJHLVDSSOLHGWRSLQRI
,&DQGWKHWUDQVPLWDXGLRGDWDPRGXODWLRQVLJQDOLV
DSSOLHGWRSLQ7KHPRGXODWLRQVLJQDOLVDOVRDSSOLHG
WRWKH7&;2DVGHVFULEHGLQWKHQH[WVHFWLRQ7KH
RXWSXWVLJQDORIWKH9&2RQSLQLVDSSOLHGWRD
7VSOLWWHUIRUPHGE\557KLV QHWZRUNURXWHVWKH
9&2VLJQDOWREXIIHUDPSOLILHUV44DQGDOVR WR
47KHVHVWDJHVSURYLGHDPSOLILFDWLRQDQGLVRODWH