FEDL 7012-03-01
1
Semiconductor
ML7012-03
Examples of Level Diagram
(1) Modem transmit: VDD ≥ 3 V
AOUT = –20 dBm, RCAO = –20 dBm, TXAN = –14 dBm, TXAP = –14 dBm, LINE = –16 dBm
(S34 = 2 dB (initial value), R5/R4 = 2, transformer loss = 2 dB)
(2) DTMF transmit: VDD ≥ 3 V: high group level
The low group levels are approximately 1 dB smaller than the values below.
AOUT = –14.5 dBm, RCAO = –14.5dBm, TXAN = –8.5 dBm, TXAP = –8.5 dBm, LINE = –10.5 dBm
(S35 = 0 dB (initial value), R5/R4 = 2, transformer loss = 2 dB)
(3) Modem transmit: VDD ≥ 2.7 V
AOUT = –20 dBm, RCAO = –20 dBm, TXAN = –15.9 dBm, TXAP = –15.9 dBm, LINE = –17.9 dBm
(S34 = 2 dB (initial value), R5/R4 = 1.6, transformer loss = 2 dB)
(4) DTMF transmit: VDD ≥ 2.7 V: high group level
The low group levels are approximately 1 dB smaller than the values below.
AOUT = –14.5 dBm, RCAO = –14.5 dBm, TXAN = –10.4 dBm, TXAP = –10.4 dBm, LINE = –12.4 dBm
(S35 = 0 dB (initial value), R5/R4 = –1.6, transformer loss 2 dB)
(5) Maximum modem receive:
LINE = –9 dBm, connecting point of R6, and R7 = –11 dBm, GSR = –15 dBm
(R8/R7 = 0.63 = –4 dB, transformer loss = 2 dB)
(6) Minimum modem receive
LINE = –40 dBm, connecting point of R6 and R7 = –42 dBm, GSR = –46 dBm
(R8/R7 = 0.63 = –4 dB, transformer loss = 2 dB)
Connection of Crystal Oscillator
Connect a 11.0592 MHz crystal unit and a 1 MΩ feedback resistor between OSC0 and OSC1.
The values of capacitors C01 and C02 connected between OSC0 and GND, and OSC1 and GND vary with the load
capacitance of the crystal unit and the wiring capacitance of the board. Set the values by the crystal manufacture’s
matching evaluation.
If an external clock is used, input it to OSC0.
C01
15 pF
OSC0
ROSC
11.0592 MHz
OSC1
1 MΩ
C02
15 pF
20/22
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