Physio Control LIFEPAK 9 - Page 35

© August 1993 Physio—Control
Description 1
Table 1-3 Preamp Pulse Widths
Pulses Pulse Duration
atTP17 AtTP6(ms) Result on Preamp Setup
DO
JO
ón
bh
YN
ma
NON
DN
ーー
=|
pudo
S|
Det
S|
Se
=
pe
N
=
CTO
WON
AA
WN
=
©
64 Not used
128 Not used
192 Not used
256 Lead III
320 Lead II
384 Lead I
448 Std
512 Lead III + Cal
576 Lead II + Cal
640 Lead I + Cal
704 Std + Cal
768 Lead III + Leads Coil Drive and Switch Smooth
832 Lead II + Leads Coil Drive and Switch Smooth
896 Lead I + Leads Coil Drive and Switch Smooth
960 Std + Leads Coil Drive and Switch Smooth
1024 Lead III + Cal + Leads Coil Drive and Switch Smooth
1088 Lead II + Cal + Leads Coil Drive and Switch Smooth
1152 Lead I + Cal + Leads Coil Drive and Switch Smooth
1216 Std + Cal + Leads Coil Drive and Switch Smooth
1280 Lead III + Paddles Coil Drive and Switch Smooth
1344 Not used
1408 Not used
The +1mV calibration signal is created by an instruction from the System
microprocessor which sets U33 pin 7 high. When U43A closes, a -SV offset
signal is applied to U44A pin 2 and U44B pin 6. This adds a differential
offset of approximately +1mV to the input without changing the gain of the
input stages.
Filtering. Filtering provides a uniform signal bandwidth during normal
operation. The preamp filtering is performed by two stages centered around
op amps U44C, U45D, U45A, and U45B. In the first stage, U44C and U45D
function as a high-pass filter for Preamp, DC Restore, and switch smoothing,
blocking freguencies below 0.024Hz. In the second stage, low-pass filter
U45A removes freguencies above 200Hz. U45B functions as a 540Hz notch
filter.
DC Restore. The DC Restore circuit compensates for any unwanted dc
offset originating from switch smoothing, defibrillation, or motion artifact.
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