Datasheet

Ch1

ADC

Modulation

Block

VREFP

AVSS

RESP_MOD_EN

Demodulation

Block

RESP_CTRL

RESP_MOD_CLK

RESP_DEMOD_EN

Ch1

PGA

RESP_FREQ

CLK GEN

CLK (512 kHz)

I/O

RESP_CTRL

GPIO1

GPIO2

RESP_MODP

RESP_MODN

IN1P

IN1N

EMI

Filter

MUX

BIAS

PGA1P PGA1N

47 nF

ADS1291

ADS1292

ADS1292R

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SBAS502B –DECEMBER 2011–REVISED SEPTEMBER 2012

Internal Respiration Circuitry with Internal Clock (ADS1292R)

This mode is set by RESP_CTRL = 0. Figure 54 shows a block diagram of the internal respiration circuitry. The

internal modulation and demodulator circuitry can be selectively used. The modulation block is controlled by the

RESP_MOD_EN bit and the demodulation block is controlled by the RESP_DEMOD_EN bit. The modulation

signal is a square wave of the magnitude VREFP – AVSS. When the internal modulation circuitry is used, the

output of the modulation circuitry is available at the RESP_MODP and RESP_MODM pins of the device. This

availability allows custom filtering to be added to the square wave modulation signal. In this mode, GPIO1 and

GPIO2 can be used for other purposes. The modulation frequency of the respiration circuit is set by the

RESP_FREQ bits.

Figure 54. Internal Respiration Timing Diagram

Product Folder Links: ADS1291 ADS1292 ADS1292R