ADS1291_14 Datasheet, PDF (57/75 Pages) Texas Instruments – Power, 2-Channel, 24-Bit Analog Front-End for Biopotential Measurements

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ADS1291
ADS1292
ADS1292R
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.
CLK (512 kHz)
RESP_MODP
RESP_MODN
CLK GEN
RESP_FREQ
Modulation
Block
RESP_MOD_EN
RESP_MOD_EN
RESP_CTRL
VREFP
AVSS
RESP_CTRL
I/O
RESP_MOD_CLK
I/O
GPIO1
IN1P
V_BIAS
IN1N
EMI
Filter
MUX
Ch1
PGA
Demodulation
Block
Ch1
ADC
RESP_DEMOD_EN
PGA1P
PGA1N
47 nF
Figure 54. Internal Respiration Timing Diagram
I/O
GPIO2
Copyright © 2011–2012, Texas Instruments Incorporated
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