Features: ·FULL ECHO CANCELLINGCAPABILITY FULLY COMPATIBLE WITH THE ST7543
.(7543mode) 16-BIT OVERSAMPLING A/D AND D/A CONVERTERS
- Programmable down-sampling frequency from 7200 to 16000Hz
- Sampling frequency can be 3, 4, 6, 8, 12, 16 x Symbol rate
- Programmable Over sampling frequency (128 or 160 x Sampling frequency)
- The ST7544 can work with external oversampling clocks
.LOW POWERCONSUMPTION :
- 260mWoperatingpower at the nominal crystal frequency of 36.864MHz
- 160mW operating power at the crystal frequency of 18.432MHz
- Less than5mWin theLOW-POWER RESET
. MODE .1.2MM CMOS PROCESS 44-PIN PLCC OR 44-PIN TPQFP (1.4mm body thickness)
- Programmable Symbol rate (600, 1200, 1600,2400, 2560, 2743, 2800, 2954, 3000, 3200,3429 and 3491)
- Bit rates of 300 bps, 600bps, 1200 and all multiples of 2400 bps up to 28800 bps can be generated
- Dynamic range : 92dB with a sampling frequency 9600Hz, Oversampling ratio 160
- Total harmonic distortion : -89dB
.ON CHIPREFERENCE VOLTAGE
·THREE PROGRAMMABLE DIGITAL FILTERS
SECTIONS :
- Tx interpolation filter
- Rx decimation filter
Up to 14th order each
- Rx reconstruction filter
. Coefficients loaded into RAM ANCILLARY CONVERTERS FOR EYE-DIA GRAM MONITORING
· CLOCK SYSTEM BASED ON DIGITAL PHASE LOCKED LOOPS
- Separate Tx DPLL and Rx DPLL
- Terminal clock input for Tx synchronization on all multiples of 2400Hz (V.Fast synchronization mode) or on sub-multiple of baud rate (7543 synchronization mode)
- Bit, Baud, Sampling and Highest synchronous clock outputs
- Maximummaster clock frequency is 38MHz SINGLE OR DUAL SYNCHRONOUS SERIAL
.INTERFACE TO DSP SINGLEPOWER SUPPLY VOLTAGE : +5VDescriptionThe ST7544 is a single chip Analog Front-End (AFE) designed to implement high speed voicegrade Modems up to 28800 bps with echo cancelling capability.
Associated with one or several Digital Signal Processors (DSP), such as the ST189XX family, it provides a powerfulsolution for the implementation of multi-mode Modems meeting CCITT (V.21, V.22, V.22 bis, V.23, V.26, V.27, V.29, V.32,V.32 bis and V.33) and BELL (103, 202, 212A...) recommendations. ST7544 is fully compatible with the ST7543 in 7543 mode and is also well suited emerging applications involving bit rates up to 28800 bps (in the VFast synchronization mode).
The ST7544 transmit section includes a 16-bit over-sampling D/A converter with a programmable interpolating filter. The receive section includes a 16-bit oversampling A/D converter with two programmable filters (one for decimation and the other for reconstruction).Oversampling ratio is selectable to either 128 or 160.Two additional 8-bit D/A converters allow eyediagram monitoring on a scope for modem performance adjustment.
Two independantclock generator systems are provided, one synchronized on the Tx rate and the other on the Rx rate.
In External Clock Mode, external oversampling clocks can be provided to the ST7544.
Two independant synchronous serial interfaces (SSI) allow several versatile ways of communicating with standard DSPs.
To savepower, e.g. in lap-topmodem applications,the lowpower reset mode can be used to reduce the power consumption to less than 5mW.
ST7544 Data Sheet
