ST75951 datasheet(6/21 Pages) STMICROELECTRONICS

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MUX

DGND

AGND1 AGND2

REFN

REFP

RESET

PWRDWN

HC0 HC1

REFERENCE

VOLTAGE

GAIN

Bit DR

MUX

DAA CONTROL + GPIO

CMS

CMP

TSTA1 TSTA2

M/S MCM

XTALIN

(MCLK)

XTALOUT

GPIO0 GPIO1 GPIO2 GPIO3

TSTD1

SCLK

DOUT

DIN

GPI

STLC75951

RING

AUXIN

DETECTOR

LOW

PASS

FILTER

ANALOG

MODULATOR

LOW-PASS

(0.425 x Sampling

Frequency)

GAIN

ATTE

2dB

0dB

6dB

INFINITE

DAC 1 BIT

First Order

Differential

Switched

Capacitor

Filter

2nd ORDER

MODULATOR

LOW-PASS

(0.425 x Sampling

Frequency)

CLOCK GENERATOR

HIGH

PASS

FILTER

BLOCK DIAGRAM

FUNCTIONAL DESCRIPTION

ST75951 is a modem AFE front-end integrating the

modem side of Krypton K951 and fully compatible

to work with ST952.

1 - Transmit Section

The functions included in the transmit section are :

- D/A converter,

- F0 modulator,

- Programmable stage +2dB gain, 0dB gain, 6dB

attenuation or infinite attenuation,

- Transmit Filter including noise shaper and Sinx/x

correction.

The digital base Band data (DIN) are converted and

modulated at F0 and send differentially (D1, D2) to

ST952 through capacitive connection.

2 - Receive Section

The functions included in the receive section are :

- Main and Aux inputs,

- Programmable gain 0/6dB,

- A/D converter,

- F0 demodulator,

- Receive filter.

The analog differential Main input signal (D3, D4)

coming from ST952 is demodulated at F0, goes to

the multiplexer and gain receive block then is digi-

tally converted and output on DOUT which is the

base band data.

Thanks to the multiplexer, we can also process

base band analog signal on AUXIN.

3 - Clock Generator

ST75951 generates all clocks from either a Master

clock input on XTALIN (MCLK) or a crystal oscillator

connected between XTALIN and XTALOUT.

The bypass of the divider M and Q is selected by

setting the MCM input pin to ’0’.

To be able to provide externally the sampling fre-

quency (Slave mode), M/S input pin must be set

to ’0’ (see Figure 2).

ST75951

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