ADA4254ACPZ-R7 datasheet(49/59 Pages) AD

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Data Sheet

ADA4254

Rev. B | Page 49 of 59

WIRE BREAK DETECT REGISTER (WB_DETECT) DETAILS

Table 20. WB_DETECT Register Details (Register 0x07)

Bit Name

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

WB_G_RST_DIS

Reserved

SW_F1

SW_F2

WB_CURRENT[1:0]

Access

Reserved

Reset

Reserved

PGIA

D12

VDDH

+IN1

–IN1

+IN2

–IN2

–OUT

+OUT

WB_CURRENT[1:0]

Figure 107. Wire Break Current Connectivity

Bit 7, WB_G_RST_DIS—Wire Break Gain Reset Disable

The WB_G_RST_DIS bit can be set to 1 to prevent the gain

settings in the GAIN_MUX register from being overridden to

1/16 V/V when the SW_F1 bit or the SW_F2 bit are set to 1.

Bit 3, SW_F1, and Bit 2, SW_F2—Fault Switch Selection

The SW_F1 bit and the SW_F2 bit are used to connect the wire

break current sources to the inputs, as shown in Figure 107.

Setting SW_F1 or SW_F2 to 1 closes each corresponding

switch. Both switches can be closed simultaneously. When

SW_F1 or SW_F2 are set to 1 and WB_G_RST_DIS is cleared

to 0, the gain settings in the GAIN_MUX register are temporarily

overridden to the default values. Reading GAIN_MUX while

SW_F1 or SW_F2 are set to 1 does not show this temporary

override. When SW_F1 or SW_F2 are cleared to 0, the gain is

also restored to the previous value.

Bits[1:0], WB_CURRENT—Detection Current Selection

Table 21 shows four different current values that can be used

for wire break detection. Both current sources are set to the

programmed value. The comparator used to detect a wire

break event has a threshold at approximately 4 V from VDDH.

Table 21. Wire Break Detect Current Values

WB_CURRENT[1:0] Bits

Current

Source Value

Threshold

VDDH = 15 V

Bit 1

Bit 0

250 nA

44 MΩ

2 μA

5.5 MΩ

4 μA (default)

2.75 MΩ

16 μA

688 kΩ

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