AS-Interface Slave IC

AS2701A (ISA3+)

Rev. C, October 2000

Page 2 of 16

Key Feature s

• Simple two-wire bus (AS-Interface line)

• Transmission of both power and signal on the AS-Interface line

• Decoupling of power and signal by the IC without additional external devices

• Transmitting protocol for using the IC and the AS-Interface master in the trans-

mit/receive modes

• Switching of max. 31 AS-Interface slave ICs on one bus possible

• Power supply of peripheral devices from the AS-Interface slave IC of up to 35mA@24V

• Quartz oscillator for 5.333 MHz without external capacitances

• Standards: AS-Interface–Spec V2.0 and EN 50295

General Descriptio n

The signal transmission between the master and the slaves in the AS-Interface system is

performed by a parallel two-line wire (AS-Interface line) to which the IC is connected only via a

polarity protection diode and a suppressor diode. The line is powered by a direct dc voltage of

up to 33.1 V, on which data pulses with signal amplitudes of (3...8) Vpp are superimposed.

The IC extracts its own power and the power for peripherals from the line and detects the bus

signals.

The AS-Interface slave IC consists of the following blocks:

• Receive Block

• Transmit Block

• Digital Logic Block

• Emergency Control Block

• Internal and External Power Supply with Signal decoupling

• Oscillator

• Power on Reset

• High Voltage I/O

Block Diagra m

LTGP

switch

Emergency and

Temperature

Control Block

Receive Block

Transmit Block

Internal Power

Supply

Power-On

Reset

Oscillator

Signal Decoupling

Ext. Power Supply

Digital

Block

HV-

I/O

LTGN

UOUT

CDC

TEST

U5R

SCL

SDA

DSTBn

P0...P3

D0...D3

PSTBn

imp_pos, imp_neg