M59330P

Rev.1.0, Sep.16.2003, page 3 of 10

Transmission Channel Anomaly Detection and Communication Functions

The M59330P uses driver overcurrent detection functions and transmission signal logic error detection functions to

detect anomalies in the transmission channel, and outputs an error signal (

ERR (pin 3) = "L" ) accordingly.

anomaly occurrence.

(1) Overcurrent detection

The drivers of the BUS(+) pin (pin 7) and BUS(-) pin (pin 6) of the M59330P are provided with overcurrent detection

circuits. When excessive current flows in a driver, the driver is turned off, and an error signal (

ERR (pin 3) = "L" ) is

output. When overcurrent is detected, the driver is maintained in the off state until error reset.

The drivers for the BUS(+) pin (pin 7) and the BUS(-) pin (pin 6) are independent; depending on the circumstances of

the anomaly, both may be turned off.

A filter is incorporated to prevent erroneous operation due to transient currents when a driver is turned on, and an

overcurrent state is not detected for a short period of time (several hundred ns). The detection current is set at approx.

180 mA.

(2) Logical anomaly detection

M59330P transmission signals operate at opposite phases, and by comparing the signals, anomalies in the transmission

channel are detected. The signals are compared at a preset time relative to an edge of the signals of the transmission

channels (BUS(+) , BUS(-)), and if they do not coincide, it is assumed that an anomaly has occurred in one of the

transmission channels, and an error signal (

ERR (pin 3) ="L") is output. When the next edge is detected within the

preset time, this edge is taken as a new reference for timing, and if noncoincidence continues for longer than the preset

time, an anomaly is detected. The time is set to approx. 4.2

µs.

Logical anomaly detection does not support multiple error modes.

When only a logical anomaly is detected, the driver is not turned off. A driver is turned off upon anomaly detection

only when overcurrent is detected.