GMSK Modem
CMX589A
2 Signal List
Pin No.
E2/D5/
D2/P4
Signal
Type
Description
1
2
XTALN
O/P
I/P
The output of the on-chip clock oscillator.
XTAL/CLOCK
The input to the on-chip Xtal oscillator. A Xtal, or externally derived
clock (fXTAL) pulse input should be connected here. If an externally
generated clock is to be used, it should be connected to this pin and the
XTALN pin left unconnected. Note: Operation without a suitable Xtal or
clock input may cause device damage.
3
4
5
6
7
8
ClkDivA
I/P
I/P
I/P
I/P
I/P
I/P
Logic level inputs control the internal clock divider and therefore the
transmit and receive data rate. See Table 4.
ClkDivB
Logic level inputs control the internal clock divider and therefore the
transmit and receive data rate. See Table 4.
RxHOLDN
RxDCacq
PLLacq
A logic ‘0’ applied to this input will freeze the Clock Extraction and Level
Measurement circuits unless they are in ‘Acquire’ mode.
A logic ‘1’ applied to this input will set the Rx Level Measurement
circuitry to the ‘Acquire’ mode. See Table 6.
A logic ‘1’ applied to this input will set the Rx Clock Extraction circuitry
to the ‘Acquire’ mode. See Table 5.
Rx PSAVE
A logic ‘1’ applied to this input will powersave all receive circuits except
for Rx CLK output (which will continue at the set bit-rate) and cause the
Rx Data and Rx S/N outputs to go to a logic ‘0’.
9
VBIAS
power The internal circuitry bias line, held at VDD/2. This pin must be
bypassed to VSS by a capacitor mounted close to the pin.
10
11
12
13
Rx FB
O/P
I/P
Output of the Rx Input Amplifier.
Input to Rx input amplifier.
Rx Signal In
VSS
power Negative supply (GND).
DOC1
O/P
O/P
I/P
Connections to the Rx Level Measurement Circuitry. A capacitor should
be connected from this pin to VSS
.
14
15
DOC2
BT
Connections to the Rx Level Measurement Circuitry. A capacitor should
be connected from this pin to VSS
.
A logic level to select the modem BT (the ratio of the Tx Filter's -3dB
frequency to the Bit-Rate). A logic ‘1’ = BT of 0.5 and a logic ‘0’ = BT of
0.3.
ã 2002 CML Microsystems Plc
4
D/589A/4
CMLMICRO [ CML MICROCIRCUITS ]
