73M1903C
Modem Analog Front End
DATA SHEET
SYSTEM CONTROL REGISTERS
Register00 (CTRL): Address 00h
Reset State 08h
BIT 7
BIT 6
BIT 5
TXBST
BIT 4
BIT 3
BIT 2
RXG1
BIT 1
RXG0
BIT 0
RXGAIN
ENFE
SelTX2
TXBST0 TXDIS
ENFE
(0X00[7]) Enable Front End.
1 = Enable the digital filters and analog front end.
0 = Disable the analog blocks shut off the clocks to the digital and analog receive/transmit
circuits.
SelTX2
(0X00[6]) Select Tx driver 2
1 = Selects Secondary transmitter (TXAP2 and TXAN2) if TXDIS=0
0 = Selects Primary transmitter (TXAP1 andTXAN1) if TXDIS=0
TXBST1
(0X00[5])
1 = Add a gain of 1.335dB (16.6%) to the transmitter; also the common mode voltage of the
transmit path is increased to 1.586V. This is intended for enhancing DTMF transmit power
only and should not be used in data mode.
0 = No gain is added
TXBST0
TXDIS
(0X00[4])
1 = A gain of 1.65dB(21%) is added to the transmitter
0 = The gain of the transmitter is nominal
(0X00[3])
1 = Tri-state the TXAP1,2 and TXAN1,2 pins, provides a bias of VBG into 80 kꢀ for each
output pin
RXG(1:0) (0X00[2:1]) Rx Gain Selection
00 = 6 dB Receive Gain
01 = 9 dB
10 = 12 dB
11 = 0 dB
RXGAIN
(0X00[0]) 20 dB RxGain Enable. This gain selection can be used for line snoop or Caller ID
detection.
1 = Increase the gain of the receiver by 20 dB.
0 = Normal operation
Register01 (TEST): Address 01h
Reset State 00h
BIT 7
BIT 6
BIT 5
ANALB
BIT 4
INTLB
BIT 3
BIT 2
BIT 1
BIT 0
HC
TMEN
DIGLB
CkoutEn RXPULL SPOS
TMEN
(0X01[7]) Test Mode Enable.
0 = Normal operation
1 = Enable test modes.
DIGLB
(0X01[6]) Digital Loop back Enable
0 = Normal operation
1 = Tie the serial bit stream from the digital transmit filter output to the digital receive filter
input.
ANALB
(0X01[5]) Analog Loop back Enable
0 = Normal operation
1 = Tie the analog output of the transmitter to the analog input of the receiver.
Page: 12 of 46
© 2005-2008 TERIDIAN Semiconductor Corporation
Rev 4.3
TERIDIAN [ TERIDIAN SEMICONDUCTOR CORPORATION ]
