AS-Interface Slave IC

AS2702 (SAP4.1)

Rev. C, January 2001

Page 13 of 18

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3DUDPHWHU

PLQ

PD[

8QLW

1RWH

ILED

Sink current @ output L

10

mA

VOUT = 1V

IOUTHI

Leackage current @ output off

- 10

10

µA

VOUT = 5V

VIN

Acceptable input voltage @ out-

put off

- 0.3

40

V

fBLINK

Blinking frequency

2

3

Hz

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AS2702 is equipped with a watchdog timer to supervise data communication by monitoring

the strobe signals at pins DSTBn and PSTBn.

If a parameter or data strobe is not followed by a consecutive strobe within a time period of

50 … 100 ms, the watchdog is triggered and initiates a ‘soft’ reset, see section ‘Reset’

5(6(7

There are 2 categories of reset-events, leading to 2 slightly different reset-conditions of the

slave device:

1) a ‘hard’ reset taking place at power-up and power-down of supply-voltages U5R and

UOUT.

At power-up the slave device leaves reset-condition as soon as U5R has passed 3.75V

and UOUT has passed VCOMOFF = nom. 10V.

At power-down the slave device is forced into reset-condition as soon as U5R drops below

3.75V.

(Tolerance of the threshold voltages referred to is -/+ 5%.)

2) a ‘soft’ reset, resulting from one of the following events:

2.1) Data strobe pin DSTBn is kept L for more than 100 ms;

2.2) Master command ‘RESET SLAVE’ is received;

2.3) Master command ‘RESET BROADCAST’ is received;

2.4) The communication watchdog is triggered.

A ‘hard’ reset event conditions the slave device as follows:

• Internal states (counters, flags, …) are reset

• The slave device’s receiver is desynchronized from the AS-interface bus

• The low-side open-drain output stages at ports D3, …, D0 and ports P3, …, P0 are

switched off

• Any test-mode will be cancelled.

A ‘soft’ reset has the following consequences:

• A regular, nominal 6µs L-phase strobe is generated on both the DSTBn and PSTBn pin

• The low-side open-drain output stages at ports D3, …, D0 and ports P3, …, P0 are

switched off

• Internal states (counters, flags, …) are reset, however the following states and operations

are not affected:

•

the timer function which controls blinking of LED1 and LED2

•

the data communication watchdog

•

any testmode

•

any EEPROM write operation.

Remark: