ZSSC3136 Datasheet

© 2016 Integrated Device Technology, Inc.

16

January 22, 2016

2.6.

Analog or Digital Output

The AOUT pin is used for analog output and for one-wire communication (OWI). The latter can be used for digital

readout of the conditioned sensor signal and for end-of-line sensor module calibration. The ZSSC3136 supports

different modes for the analog output in interaction with OWI communication:

Analog output is deactivated; OWI readout of the signal data is enabled.

Analog output starts after the startup phase and after the OWI startup window if OWI

communication is not initiated; OWI communication for configuration or for end-of-line

calibration can be started during the OWI startup window (maximum ~500ms) by sending the

START_CM command.

Analog output starts after the startup phase; OWI communication for configuration or for end-

of-line calibration can be started during the OWI startup window (maximum ~500ms) by

sending the START_CM command; for command transmission, the driven analog output at

the AOUT pin must be overwritten by the external communication master (AOUT drive

capability is current-limited).

Analog output starts after the startup phase; OWI readout of the signal data is disabled.

The analog output signal is driven by an offset compensated, rail-to-rail output buffer that is current-limited to

prevent damage to the ZSSC3136 from a short circuit between the analog output and power supply or ground.

Output resolution of at least 12-bit in the range of 10% to 90% FS is ensured by a 12.4-bit resistor string DAC.

2.7.

Serial Digital Interface

The ZSSC3136 includes a serial digital I²C

(OWI). The digital interfaces allow configuration and calibration of the sensor module. OWI communication can be

used to perform an end-of-line calibration via the analog output pin AOUT of a completely assembled sensor

module. The interfaces also provide the readout of the conditioned sensor signal data during normal operation.

Refer to the ZSSC313x Functional Description for a detailed description of the serial interfaces and the

communication protocols.

2.8.

Failsafe Features

The ZSSC3136 detects various failures. When a failure is detected, Diagnostic Mode (DM) is activated. DM is

indicated by setting the output pin AOUT to the Lower Diagnostic Range (LDR). When using digital serial

communication protocols (I²C™ or OWI) to read conditioning results data, the error status is indicated by a

specific error code.

A watchdog timer controls the proper operation of the microcontroller. The operation of the internal oscillator is

monitored by an oscillator-failure detection circuit. EEPROM and RAM content are checked when accessed.

Control registers are parity protected.

The sensor connection is checked with regard to broken wires or short circuits (sensor connection check, sensor

short check).

The connection of an external temperature sensor can be monitored by the temperature sensor check.

In addition to these checks, the ZSSC3136, which is optimized for failsafe switch applications, also provides a

ROM check after power-on and monitoring of the sensor common mode voltage (sensor aging check).