Biomedical Engineering Reference
In-Depth Information
J5
B
NC
IC29
R55
RF
16
17
1
2
FB
-IN
VOUT
OUT COM
19
V_CAP_OUT
+IN
18
ICOM
R56
RG
14
15
3
4
+VISS
-VISS
+VOSS
-VOSS
AD210
3
0
2
9
+15V_NON_ISO
C47
10uF
C48
.01uF
D
Non Iso GN
J14
B
NC
IC35
R102
RF
16
17
1
2
FB
-IN
VOUT
OUT COM
19
I_CAP_OUT
+IN
18
ICOM
R103
RG
14
15
3
4
+VISS
-VISS
+VOSS
-VOSS
AD210
3
0
2
9
+15V_NON_ISO
C70
.01uF
C69
10uF
Non Iso GND
Figure 8.42
An AD210AN isolation amplifier is used to sample the voltage across the capacitor bank (using the voltage divider formed
by resistors R84 and R86 on the high-voltage capacitor charging circuit). A second AD210AN samples the instantaneous capacitor
charge-discharge current by sampling the voltage developed across the 0.5-Ω
current-measurement resistor (R90 on the high-voltage
capacitor charging circuit).
Control of the Shock Box
As shown in Figure 8.43, a Microchip PIC 16C77 microcontroller (IC24) is the main
shock-box controller. A 32-kHz crystal-controlled clock operates the timers, and a 4-MHz
crystal-controlled clock runs processing upon wake-up. Correct clock operation is veri
ed
through an independent
RC
circuit (R42 and C31). This microcontroller is powered from
one of the module's batteries through a 5-V regulator (IC20 on the battery-charging cir-
cuit) and will thus have constant supply of energy available for housekeeping of the mod-
ule during system power-downs.
The microcontroller communicates with the programming GUI computer through a
serial interface. A four-line RS232 protocol (TX/RX,RTS/CTS) protocol is implemented
fi
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