DESIGN AND DEVELOPMENT OF MEDICAL ELECTRONIC ...

SHOCK BOX PROTOTYPE 429V_CAP_OUTR56RGR55RF161719181415IC29FB-IN+INICOM+VISS-VISSPWRPWR COMVOUTOUT COM+VOSS-VOSS1234J5BNCAD21030 29+15V_NON_ISOC4710uFC48.01uFDNon Iso GNI_CAP_OUTR103RGR102RF161719181415IC35FB-IN+INICOM+VISS-VISSPWRPWR COMKVOUTOUT COM+VOSS-VOSS1234J14BNCAD21030 29+15V_NON_ISOC6910uFC70.01uFNon Iso GNDFigure 8.42 An AD210AN isolation amplifier is used to sample the voltage across the capacitor bank (using the voltage divider formedby resistors R84 and R86 on the high-voltage capacitor charging circuit). A second AD210AN samples the instantaneous capacitorcharge–discharge current by sampling the voltage developed across the 0.5-Ω current-measurement resistor (R90 on the high-voltagecapacitor charging circuit).Control of the Shock BoxAs shown in Figure 8.43, a Microchip PIC 16C77 microcontroller (IC24) is the mainshock-box controller. A 32-kHz crystal-controlled clock operates the timers, and a 4-MHzcrystal-controlled clock runs processing upon wake-up. Correct clock operation is verifiedthrough an independent RC circuit (R42 and C31). This microcontroller is powered fromone of the module’s batteries through a 5-V regulator (IC20 on the battery-charging circuit)and will thus have constant supply of energy available for housekeeping of the moduleduring system power-downs.The microcontroller communicates with the programming GUI computer through aserial interface. A four-line RS232 protocol (TX/RX,RTS/CTS) protocol is implemented