AS-Interface Slave IC
AS2702 (SAP4.1)
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ILED
IOUTHI
VIN
fBLINK
3DUDPHWHU
Sink current @ output L
Leackage current @ output off
Acceptable input voltage @ out-
put off
Blinking frequency
PLQ
10
- 10
- 0.3
2
PD[
10
40
3
8QLW
1RWH
mA VOUT = 1V
µA VOUT = 5V
V
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:
Rev. C, January 2001
Page 13 of 18