ADPD7000 datasheet(32/127 Pages) AD

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Data Sheet

ADPD7000

APPLICATIONS INFORMATION

analog.com

Rev. 0 | 32 of 127

Lead Off

DCLO detection uses the ECG_STATUS register to identify the lead

connection status. Figure 50 shows an example of DCLO detection.

In the case, R1, R2, and R3 are the contact impedances at ECGIP,

ECGIN, and RLD, respectively.

Figure 50. DCLO Detection Example

When using source current at ECGIP and ECGIN, the dc excitation

current setting (ECG_DCLO_MAG) follows Equation 11:

If R1 = R2 = R3 = 3R,

DCLO Current Magnitude>Higℎ

Tℎresℎold Voltage/3R

(11)

Generally, the DCLO current magnitude setting is rounded up to

nearest register value.

Table 18 is the ECG DCLO status truth table.

ACLO threshold selection depends on the particular cable, elec-

trode, or protection scheme because these parameters are typically

unique for the specific use case. Identifying the appropriate thresh-

old can start with a high threshold and ratchet it down until a lead

off is detected, then increase the threshold by some safety margin.

Table 19 shows the low threshold of electrode difference capaci-

tance for ACLO detection.

Table 18. ECG DCLO Status Truth Table

Status

ECGIN_DCLO_HI_STATUS

ECGIP_DCLO_HI_STATUS

ECG_DCLO_STATUS

All Leads Failed

No Lead Failed

RLD Failed

ECGIN Right Arm (RA) Failed

ECGIP Left Arm (LA) Failed

Table 19. Low Threshold of Electrode Difference Capacitance for ACLO Detection

ECG_ACLO_THRESHOLD

ECG_ACLO_MAG

0x1

0x2

0x3

0x4

0x5

0x6

0x7

0x0

0.04 nF

0.08 nF

0.13 nF

0.17 nF

0.21 nF

0.25 nF

0.29 nF

0x1

0.05 nF

0.1 nF

0.14 nF

0.19 nF

0.24 nF

0.29 nF

0.33 nF

0x2

0.06 nF

0.11 nF

0.17 nF

0.22 nF

0.28 nF

0.33 nF

0.39 nF

0x3

0.07 nF

0.13 nF

0.2 nF

0.27 nF

0.33 nF

0.4 nF

0.47 nF

0x4

0.08 nF

0.17 nF

0.25 nF

0.33 nF

0.42 nF

0.5 nF

0.58 nF

0x5

0.11 nF

0.22 nF

0.33 nF

0.44 nF

0.56 nF

0.67 nF

0.78 nF

0x6

0.17 nF

0.33 nF

0.5 nF

0.67 nF

0.83 nF

1 nF

1.17 nF

0x7

0.33 nF

0.67 nF

1 nF

1.33 nF

1.67 nF

2 nF

2.33 nF

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