Datasheet

Device

EMI

Filter

ADC

PGA

3-Bit

DAC

(1)

COMP_TH[2:0]

Fault Detect

Control Register

FAULT_STATP

FAULT_STATN

INP

INN

AVDD

AVSS

Voltage

Current

Sensing

ADS131E04

ADS131E06

ADS131E08

SBAS561A –JUNE 2012–REVISED APRIL 2013

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FAULT DETECTION

The ADS131E0x have integrated comparators that can be used in conjunction with the external pull-up or pull-

down resistors (R) to detect various fault conditions. The basic principle is to compare the input voltage with the

one set by the fault comparator 3-bit digital-to-analog converter (DAC), as shown in Figure 46. The comparator

trigger threshold level is set by the COMP_TH[2:0] bits in the FAULT register. Assuming that the ADS131E0x is

powered from ±2.5-V supply and COMP_TH[2:0] = 000 (95% and 5%), the high-side trigger threshold is set at

+2.25 V [equal to AVSS + (AVDD + AVSS) × 95%] and the low-side threshold is set at –2.25 V [equal to AVSS +

(AVDD + AVSS) × 5%]. The threshold calculation formula applies to unipolar as well as bipolar supplies.

A fault condition, such as an input signal going out of a predetermined range, can be detected by setting the

appropriate threshold level using the COMP_TH[2:0] bits. An open-circuit fault at the INP or INN pin can be

detected by using the external pull-up and pull-down resistors, which rail the corresponding input when the input

circuit breaks, causing the fault comparators to trip. To pinpoint which of the inputs is out of range, the status of

the FAULT_STATP and FAULT_STATN registers can be read, which is available as part of the output data

stream; see the Data Output (DOUT) subsection of the SPI Interface section.

(1) The configurable 3-bit DAC is common to all channels.

Figure 46. Fault Detect Comparators

Product Folder Links: ADS131E04 ADS131E06 ADS131E08