ZSC31015EAG1-R datasheet(22/52 Pages) IDT

22 / 52 page

November 14, 2016

ZSC31015 Datasheet

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 part will output a diagnostic state. The bridge will have a minimum

of 480

sec recovery time prior to the next measurement. See Table 2.3 in section 2.6 for more information.

The bridge resistance must be taken into account if the Sensor Short diagnostic feature is used. At VDD= 2.7V, the

minimum bridge resistance is 0.3K

and at V

DD = 5V, the minimum bridge resistance is 0.6K.

2.6.4.

Power Loss Detection

If the power or GND connection to the module containing the sensor bridge and the ZSC31015 is lost, the

ZSC31015 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 works when the part is configured in Analog

Output Mode. See Table 2.3 in section 2.6 for more information.

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 2.3 in

section 2.6 for more information.

ZSC31015EAG1-R 数据表(PDF) 22 Page - Integrated Device Technology