ST5481 datasheet(6/18 Pages) STMICROELECTRONICS

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ST5481

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5 - ISDN ACCESS

The device is directly connected to the ISDN line

at S0 interface point.

4 pins are dedicated to this access:

LIP, LIN: receive AMI differential signals inputs

connected to the appropriate transformer LOP,

LON: transmit AMI differential signals outputs

connected to the appropriate transformer.

The S interface access sub-function is clock-

feeded by a 15.36MHz clock signal from the

on-chip oscillator.

I431 recommendation protocols are fully imple-

mented.

The activation / deactivation command manage-

ment is done by the device.

5.1 - ISDN S Interface Synoptic

See Figure 3.

6 - USB ACCESS

The device is directly connected to the USB bus.

4 pins are dedicated to this access:

DP, DM for data exchange. VBUS, GNDBUS as

power lines.

The data transfer rate is 12 MBits. The clock is

extracted from the differential lines DP, DM by a

digital PLL from a 48MHz internal clock. This

48MHz clock is created from the 15.36MHz clock.

The USB protocol is fully implemented following

the 1.0 USB specification.

6.1 - USB Normalization

This specification refers to USB normalization

documents:

– Universal Serial Bus Specification revision 1.0

– Universal Serial Bus Common Class Specifica-

tion revision 1.0

– ST5481 belongs to the VENDOR SPECIFIC

DEVICE CLASS and to a vendor specific

subclass defined as ISDN MODEM DEVICE

SUBCLASS.

It presents ONE INTERFACE belonging to the

VENDOR SPECIFIC INTERFACE CLASS and a

vendor specific interface subclass defined as

ISDN SOFT MODEM INTERFACE SUBCLASS.

It satisfies to a vendor specific control protocol

called ISDN SOFT MODEM PROTOCOL.

Figure 3 : S-Interface Block Diagram

Line Signal

Slicers

RXNUM

CONTROL

TXNUM

- Tx multiframe control

- D channel monitoring

- Loopbacks

- Frame construction

- AMI code generation

Detector

- C/I control

- Activation state machine

- Master clocks generation

- D & E channel processing

- Auto threshold controller

- Auto equalizer controller

- Digital PLL, line synchronization

- AMI decoder

- Frame synchronization & polarity check

- Signal ID

- Multiframe control.

Pre Filter &

equalizer

2x6 bits DACs

Line

Driver

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