ADAS1000 datasheet(38/80 Pages) AD

38 / 80 page

ADAS1000/ADAS1000-1/ADAS1000-2

Data Sheet

Rev. A | Page 38 of 80

External Respiration Path

The EXT_RESP_xx pins are provided for use either with the

ECG electrode cables or, alternatively, with a dedicated external

sensor independent of the ECG electrode path. Additionally,

the EXT_RESP_xx pins are provided such that the user can

measure the respiration signal at the patient side of the RFI/

ESIS protection filters. In this case, the user must take

precautions to protect the EXT_RESP_xx pins from any signals

applied that are in excess of the operating voltage range.

External Respiration Capacitors

If necessary, the ADAS1000 allows the user to connect external

capacitors into the respiration circuit to achieve higher

resolution (<200 mΩ). This level of resolution requires that the

cable impedance be ≤1 kΩ. The diagram in Figure 67 shows the

connections at RESPDAC_xx paths for the extended respiration

configuration. Again, the EXT_RESP_xx paths can be

connected at the patient side of any filtering circuit; however,

the user must provide protection for these pins. While this

external capacitor mode requires external components, it can

deliver a larger signal-to-noise ratio. Note again that respiration

can be measured on only one lead (at one time); therefore, only

one pair of external respiration paths (and external capacitors)

may be required.

Figure 67. Respiration Measurement Using External Capacitor

±1V

LPF

LA CABLE

ECG1_LA

EXT_RESP_LA

ECG2_LL

EXT_RESP_LL

ECG3_RA

EXT_RESP_RA

ADAS1000

46.5kHz TO

64kHz

46.5kHz TO

64kHz

OVERSAMPLED

5kΩ

1kΩ

5kΩ

100pF

RESPDAC_LA

RESPDAC_RA

RESPDAC_LL

1nF TO 10nF

MUTUALLY

EXCLUSIVE

MUTUALLY

EXCLUSIVE

RESPIRATION DAC

DRIVE +

CABLE AND ELECTRODE

IMPEDANCE < 1kΩ

LL CABLE

RA CABLE

FILTER

RESPIRATION

MEASURE

RESPIRATION DAC

DRIVE –

HPF

IN-AMP AND

ANTI-ALIASING

MAGNITUDE

AND

PHASE

SAR

ADC

ADAS1000 Datasheet(PDF) 38 Page - Analog Devices

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