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Details, datasheet, quote on part number:FX489
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Datasheet text preview:
CML Semiconductor Products
PRODUCT INFORMATION
FX489
Features
GMSK Modem
Obsolete Product - For Information Only
Full-Duplex Gaussian Minimum Shift Keying Selectable BT (0.3 or 0.5) Meets RAM - MOBITEX Specification Data Rates From 4000bits/s to 19200bits/s Serial Rx and Tx Data Interfaces
Tx ENABLE Tx PS
Tx DATA
VBIAS
Rx and Tx Data Clock Generation Rx Signal Tracking Controls Rx S/N Indication Separate Rx and Tx Powersave Inputs Wireless Modem, Radio Telemetry and Data Terminal Applications
VBIAS
XTAL/CLOCK
DATA RETIME & LEVEL SHIFT
Tx FILTER
Tx OUT
Tx CLOCK
XTAL ClkDIVA
ClkDIVB
CLOCK DIVIDER
Rx DATA EXTRACT
Rx DATA
BT
VDD
Rx S/N DETECTION
Rx S/N
FX489
NEW 40kbps Modem FX589
Pin/Function Compatible
RxHold
PLLacq RxDCacq
Rx PS
Rx CIRCUIT CONTROL
Rx CLOCK EXTRACT
Rx CLOCK
VBIAS
VSS
Rx SIGNAL IN Rx FEEDBACK
+ -
Rx FILTER
Rx LEVEL MEASURE
VBIAS
DOC1
DOC2
Fig.1 Functional Block Diagram
Brief Description
The FX489 is a single-chip modem employing Gaussian Minimum Shift Keying (GMSK) modulation. Having a pin selectable BT of 0.3 or 0.5, the FX489 may be employed at data rates of between 4,000bits/s and 19,200bits/s; for use in FM radio-data links and data communication systems conforming to DOC and FCC spectrum limitations for 12.5kHz and 8,000 baud at a BT of 0.3, and 12.5, 25.0, and 50.kHz channel spacing and data rates of 4800, 9600 and 19,200 baud respectively at a BT of 0.5. The Rx and Tx digital data interfaces are bit-serial and synchronised to Rx and Tx data clocks generated by the modem. Separate Rx and Tx Powersave/ Enable inputs allow for full- or half-duplex operation. Rx input levels can be set by a suitable a.c. and d.c. level adjusting circuit built, with external components, around an on-chip Rx input amplifier. Acquisition, lock and hold of Rx data signals is made easier and faster by the use of Rx Control Inputs to clamp, detect and/or hold input data levels and can be set by the µProcessor as required. Indication is available, from the Rx S/N output, as to the quality of the received signal. The FX489, a low-power CMOS microcircuit, is available in both 24-pin plastic Small Outline (S.O.I.C) and DIL packages.
1
Pin Number
FX489DW FX489P 1
Function
Xtal: The output of the on-chip clock oscillator.
2
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 "Xtal" pin left unconnected. Note that operation of the FX489 without a suitable Xtal or clock input may cause device damage.
3
4
ClkDivA: Two logic level inputs that control the internal clock divider and hence the transmit and receive data rate. See Table 1. ClkDivB:
5
Rx Hold: A logic "0" applied to this input will `freeze' the Clock Extraction and Level Measurement circuits unless they are in `acquire' mode.
6
RXDCacq: A logic "1" applied to this input will set the Rx Level Measurement circuitry to the `acquire' mode.
7
PLLacq: A logic "1" applied to this input will set the Rx Clock Extraction circuitry to `acquire' mode (see Table 2).
8
Rx PS: A logic "1" applied to this input will powersave all receive circuits except for "Rx Clock " 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: The internal circuitry bias line, held at VDD/2, this pin must be decoupled to VSS by a capacitor mounted close to the pin.
10
Rx Feedback: The output of the Rx Input Amplifier/The input to the Rx Filter.
11
Rx Signal In: The input to Rx input amplifier.
12
VSS: Negative supply rail. Signal ground.
2
Pin Number
FX489DW FX489P 13
Function
14
Doc1: Connections to the Rx Level Measurement Circuitry. A capacitor should be connected from each pin to VSS. Doc2:
15
BT: A logic level to select the modem `BT' (the ratio of the Tx Filter's -3dB frequency to the BitRate). A logic "1" sets the modem to a BT of 0.5, a logic "0" to a BT of 0.3.
16
Tx Out: The Tx signal output from the FX489 GMSK Modem.
17
Tx Enable: A logic "1" applied to this input enables the transmit data path through the Tx Filter to the "Tx Out pin". A logic "0" will put the "Tx Out" pin to VBIAS via a high impedance.
18
Tx PS: A logic "1" applied to this input will powersave all transmit circuits except for the Tx Clock.
19
Tx Data: The logic level input for the data to be transmitted. This data should be synchronous with the "Tx Clock".
20
Rx Data: A logic level output carrying the received data, synchronous with the "Rx Clock".
21
Rx Clock: A logic level clock output at the received data bit-rate.
22
Tx Clock: A logic level clock output at the transmit-data rate.
23
Rx S/N: A logic level output which may be used as an indication of the quality of the received signal.
24
VDD: Positive supply rail. A single +5 volt power supply is required. Levels and voltages within this modem are dependent upon this supply. This pin should be decoupled to VSS by a capacitor mounted close to the pin.
3
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