D
D
V =
R
I = 1
29.15 = 29.1 V
B
m
·
·
I =
B
VREFP
VREFM
R96 + R97 + R
-
B
2.4
80.5k
=
= 29.81 A
m
DC_V =
DC_V
=
·
-
(VREFP
VREFM)
·
2.4 = 14.9mV
R
R
B
B
+ R96 +R97
0.5k
0.5k + 40k + 40k
Evaluation of the ADS1298R Respiration Function
44
SBAU181B – March 2011 – Revised Janurary 2016
Copyright © 2011–2016, Texas Instruments Incorporated
ADS1298R
5.3
Testing with Patient Simulator
5.3.1
Hardware Configuration
The output from any typical patient simulator can be directly fed into the DB15 connector. The shunts on
jumpers JP34 and JP35 should be moved from the respective default positions (shorting pins 1-2) so that
these components now short pins 2-3.
5.3.2
Software Configuration
We then must write to the following registers before we take any data. Under the
ADC Register
,
Channel
Registers
tab, the Global Channel Registers should be configured to the software default configuration
(see
for further details on software default configuration).
For internal respiration with an internal clock, set the following:
•
Channel Control Registers
control
–
Channel Input
to Normal Electrode
–
Gain
to 6
•
Configuration Register 4
–
Respiration Frequency
to 32kHz
–
Pulse Mode Enabled
to Disable
–
Lead-off Comparator Power-down
to Enable
•
RESP register set to:
–
Respiration Demodulation
to Enable
–
Respiration Modulation
to Enable
–
VREF
to VREFP
–
Respiration Phase
to 112.5 deg
–
Respiration Control
to Internal Respiration with Internal Clock
There are several options that permit users to choose different base impedance (R
B
) and delta impedance
(
Δ
R) on the simulator. For illustration purposes, a base impedance R
B
of 500
Ω
is chosen.
shows the results with R
B
= 500
Ω
and
Δ
R = 1
Ω
. The expected DC output can be calculated with
:
(6)
Current flowing through the body is calculated by
:
(7)
The peak-to-peak output can then be calculated as shown in
:
(8)