Medical Applications Guide (Rev. B - Mouser Electronics

Diagnostic, Patient Monitoring and TherapyPulse Oximetry29➔Mid-Range Solution Advantages:• Single-chip solution• High resolution• Low noise• Wide input range by adjustable integration time• No need for DC correction of the diode currentCAP1ACAP1AIN1CAP1BCAP1BCAP2ACAP2AIN2CAP2BCAP2BAV DDDualSwitchedIntegratorDualSwitchedIntegratorAGNDCHANNEL 1CHANNEL 2Mid-range solution block diagram.V REFΔΣModulatorDigitalFilterDV DDDDC112ControlTEST CONVDGNDDigitalInput/OutputCLKDCLKDVALIDDXMITDOUTDINRANGE2RANGE1RANGE0High-End Solution Advantages:• Very high resolution• High noise immunity due to differential input• High noise immunity due to synchronization on AC supply possible• High noise immunity due to free access on integration and resetswitches by SW• No need for DC correction of the diode currents• Huge input range can be covered (>24-bit) due to free programmableintegration timesIVC102aPrecision Switched Integrator TransimpedanceAmplifierIVC102Get samples, datasheets, evaluation modules and app reports at:www.ti.com/sc/device/IVC102The IVC102 is a precision integrating amplifier with FET op amp,integrating capacitors and low-leakage FET switches. It integrateslow-level input current for a user-determined period, storing theresulting voltage on the integrating capacitor. The IVC102 offers aprecise, lower-noise alternative to conventional transimpedence opamp circuits requiring a very high-value feedback resistor, and canamplify low-level sensor currents from photodiodes and ionizationchambers. The input signal current can be positive or negative.Key Features• On-chip integrating capacitors• Gain programmed by timing• Low input bias current: 750fA (max)• Low nonlinearity: 0.005% (typ)• Low switch charge injection• Fast pulse integrationApplications• Precision low current measurement• Photodiode measurements• Ionization chamber measurements• Current/charge-output sensors• Leakage current measurementV B6IVC102C360pF14V+Red and IRV REFS1aS1bS2aS2bADCADS1255MSP430orDSPIonizedChamberI IN54321C1C2 30pF10pFS1S2109V OV REFHigh-end solution block diagram.IVC102bPhotodiodeAnalogGroundS111 12 13S2Logic Low Closes SwitchesDigitalGroundV–IVC102 functional block diagram.Texas Instruments 2Q 2007Medical Applications Guide