ADS1294CZXGR datasheet(47/114 Pages) TI2

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GPIO4

GPIO2

BLKDLY

(Blocki g

n Si n l)

g a

PHASE

(ModulationCl ck)

Ch1

ADC

Modulation

Block

Demodulation

Block

RESP_CTRL[1:0]

Ch1

PGA

RespirationClock

Generator

CLK

I/O

RESP_CTRL[1:0]

GPIO3

GPIO4

GPIO2

RESP_MODP

RESP_MODN

IN1P

IN1N

EMI

Filter

MUX

ADS1294, ADS1294R, ADS1296, ADS1296R, ADS1298, ADS1298R

www.ti.com

SBAS459K – JANUARY 2010 – REVISED AUGUST 2015

9.3.1.7.8.2

Internal Respiration Circuitry with Internal Clock (RESP_CTRL = 10b, ADS129xR Only)

Figure 49 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 magnitude VREFP – AVSS. Using this

option, the output of the modulation circuitry is available at the RESP_MODP and RESP_MODN pins of the

device. This availability allows custom filtering to be added to the square-wave modulation signal. Using this

option, GPIO2, GPIO3, and GPIO4 can be used for other purposes. The modulation frequency is either 64 kHz

or 32 kHz, as set by the RESP_FREQ[2:0] bits in the CONFIG4 register. The phase of the internal demodulation

signal is set by the RESP_PH[2:0] bits in the RESP register.

When this respiration option is enabled, ADS129xR channel 1 cannot be used to acquire ECG signals. If the RA

and LA leads are intended to measure respiration and ECG signals, wire the two leads into channel 1 for

respiration and channel 2 for ECG signals.

Figure 49. Internal Respiration Block Diagram

9.3.1.7.8.3

Internal Respiration Circuitry With User-Generated Signals (RESP_CTRL = 11b, ADS129xR Only)

In this mode GPIO2, GPIO3, and GPIO4 are automatically configured as inputs and cannot be used for other

purposes. The signals must be provided as described in Figure 50. Do not use the internal master clock in this

mode.

Figure 50. Internal Respiration (RESP_CTRL = 11b) Timing Diagram

Table 10. Swtiching Characteristics for Figure 50 (1)

1.65 V

≤ DVDD ≤ 3.6V

UNIT

PARAMETER

MIN

TYP

MAX

tPHASE

Respiration phase delay

157.5

Degrees

tBLKDLY

Modulation clock rising edge to XOR signal

(1)

Specifications apply from –40°C to 85°C.

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Product Folder Links: ADS1294 ADS1294R ADS1296 ADS1296R ADS1298 ADS1298R

ADS1294CZXGR Datasheet(PDF) 47 Page - Texas Instruments

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