Application Note
6
2015-02-11
Revision 1.0
ISO2H823V2.5 Evaluation Board
Board Manual
Functional Description
ODIS (Output Disable)
The low active ODIS signal immediately switches off the output channels OUT0-OUT7. This pin has an internal
Pull-Down resistor. In normal operation the signal ODIS is high. Setting ODIS to Low clears the DRIVE register as
well. The minimum width of the ODIS signal is 5 µs.
SYNC
This pin can be used for synchronisation purpose, for normal operation pull this pin up. For details refer to the
ISO2H823V2.5
datasheet. This pin has an internal Pull-Up resistor.
ERR (Fault Indication)
The low active ERR signal contains the OR-wired diagnostic information depending on chosen serial or parallel
mode (
V
BB
undervoltage or missing voltage detection, the internal data transmission failure detection unit and the
fault(s) of the output switch).The output pin ERR provides an open drain functionality.This pin has an internal Pull-
Up resistor. In normal operation the signal ERR is high.
2.2.1
Parallel Interface Mode
WR (Write
)
By pulling this pin down, a write transaction is initiated on the AddressData bus and the data has to be valid on
the rising edge of WR. The AD7-bit of the register address has to be set to ‘1’. This pin has an internal Pull-Up
resistor.
RD (Read
)
By pulling this pin down, a read transaction is initiated on the AddressData bus and the data are driven by the
falling edge of RD. The AD7-bit of the register address has to be set to ‘0’. This pin has an internal Pull-Up resistor.
ALE (Address Latch Enable)
The pin ALE is used to select between address (ALE is in a logic High state) or data (ALE is in a logic Low state).
Furthermore, a read or write transaction can be selected with the RD and WR pin. When ALE is pulled high,
address is transferred and latched over the bit AD0 to AD7. During the time interval where ALE = High RD or WR
have to be pulled to High. During the Low State of ALE all transactions hit the same address. This pin has an
internal Pull-Down resistor.
AD7:AD0 (AddressData input / output bit7 ... bit0)
The pins AD0 .. AD7 are the bidirectional input / outputs for data write and read. Depending on the state of the
ALE pin and the AD7 pin, register addresses or data can be transferred between the internal registers and e.g.
the micro-controller. By connecting CS and WR and ALE/RST pins to GND and RD to V
CC
, the parallel direct mode
is activated.The interface can be directly controlled by the µController output ports (see
). The output pins
AD7:AD0 are in state “Z” as long as CS=1, RD=1 and WR=1.
