ZSSC3015 datasheet(21/51 Pages) ETC2

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ZSSC3015

RBicdLite-Auto™ Sensor Signal Conditioner with Diagnostics

Data Sheet

March 25, 2013

— Rev. 1.02

the prior written consent of the copyright owner. The information furnished in this publication is subject to changes without notice.

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2.6.3.

Sensor Short Check

If a short occurs between BP/BN (bridge inputs), it would normally produce an in-range output signal and there-

fore would not be detected as a fault. This diagnostic mode, if enabled, will deliberately look for such a short. After

the measurement cycle of the bridge, it will deliberately pull the BP bridge input to ground for 4

sec. At the end of

this 4

sec window, it will check to see if the BN input “followed” it down below the 0.8V comparator checkpoint. If

so, a short must exist between BP/BN, and the ZSSC3015 will output a diagnostic state. The bridge will have a

minimum of 480

sec recovery time prior to the next measurement. See Table 2.2 in section 2.6 for more

information.

2.6.4.

Power Loss Detection

If the power or GND connection to the module containing the sensor bridge and ZSSC3015 is lost, the ZSSC3015

will output a diagnostic state if a pull-up or pull-down terminating resistor greater than or equal to 5k

 is

connected in the final application. This diagnostic mode only functions when the part is configured in Analog

Output Mode. For more information, see Table 2.2 in section 2.6.

2.6.5.

ExtTemp Connection Checks

When external temperature is selected and connection checking is enabled, the part performs range checking on

the converted temperature value. If the internal ADC reading of the temperature is less than 1/32 of full scale or

greater than 63/64 of full scale then a diagnostic state is asserted. If the ExtTemp pin is shorted to ground, the

ADC reads less than 1/32. Because 100µA is sourced onto the ExtTemp pin during conversions, it naturally pulls

up during these times. If the ExtTemp pin is open, it produces an ADC reading greater than 63/64 of full scale.

Both these bad connection conditions would be detected and result in a diagnostic output. If internal temperature

is selected or sensor connection check is not enabled, then this diagnostic check is not enabled. See Table 2.2 in

section 2.6 for more information.

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