Medical Applications Guide (Rev. B - Mouser Electronics

10➔Consumer and Portable Medical DevicesSystem Support ProductsVoltage Level TranslationAs operating voltage levels in microcontrollers continue to drop, avoid may be created between peripheral devices and processorsthat disrupts interfacing between the devices. TI’s translators enablecommunication between incompatible I/Os with level translationbetween the 1.2V, 1.5V, 1.8V, 2.5V and 3V nodes. The MSP430microcontroller shown in many applications within this guide, hasa 3.6V (max) I/O tolerance: thus, translators can be used to protectthe inputs and to interface to higher voltage peripherals.Applications• LCD interface• Interface devices with different supply voltagesSuggested ComponentsV CC Power SmallestRange Max I CC FootprintComponent Description (V) (µA) Pins/PackagesSN74AVC1T45* Single-bit Dual-Supply 1.2 to 3.6 10 6/WCSPBus Transceiver(NanoStar)SN74LVC1T45 Single-bit Dual-Supply 1.65 to 5.5 4 6/WCSPBus Transceiver(NanoStar)SN74AVC2T45* Dual-bit Dual-Supply 1.2 to 3.6 10 8/WCSPTransceiver(NanoStar)SN74LVC2T45 Dual-bit Dual-Supply 1.65 to 5.5 10 8/WCSPTransceiver(NanoStar)SN74AUP1T57 Single-Supply Voltage 2.3 to 3.6 0.9 6/WCSPTranslator(NanoStar)SN74AUP1T58 Single-Supply Voltage 2.3 to 3.6 0.9 6/WCSPTranslator(NanoStar)SN74AUP1T97 Single-Supply Voltage 2.3 to 3.6 0.9 6/WCSPTranslator(NanoStar)SN74AUP1T98 Single-Supply Voltage 2.3 to 3.6 0.9 6/WCSPTranslator(NanoStar)PCA9306 Dual Bidirectional I 2 C-bus — — 8/US, WCSPand SMBus Voltage-LevelTranslator* Bus-hold option available.1.8V CPU1.8VLevelTranslatorV CCADIRA1A2A3A4A5A6A7A8GNDGNDV CCBV CCBOEB1B2B3B4B5B6B7B8GND3.3V3.3VPeripheralI 2 C Bus I/O ExpansionOften there are not enough GPIOs available on the microcontrollerto control all the desired peripherals, such as controlling LEDs orinterfacing to a keypad. An I 2 C bus expander can increase the numberof GPIOs while taking up minimal board space with the 8-pin WCSP.Key Features• Processor pin savings• Improved board routing• Reduced board spaceApplications• Keypad control• LED control• Temperature sensingSuggested ComponentsFrequencyV CC(Max) I 2 C Range -bitComponent (kHz) Address (V) WidthPCA9536 400 1000 001 2.3 to 5.5 4PCF8574 100 0100 xxx 2.5 to 6.0 8PCF8574A 100 0111 xxx 2.5 to 6.0 8PCA9554 400 0011 xxx 2.3 to 5.5 8PCA9557 400 0011 xxx 2.3 to 5.5 8PCA6107 400 0011 xxx 2.3 to 5.5 8PCF8575 400 0100 xxx 2.5 to 5.5 16PCF8575C 400 0100 xxx 4.5 to 5.5 16PCA9535 400 0100 xxx 2.3 to 5.5 16PCA9539 400 1110 1xx 2.3 to 5.5 16PCA9555 400 0100 xxx 2.3 to 5.5 16Pressure Sensor1. Silicon Pressure2. Load Cell3.0VOptionalOp AmpLPV324V REFTLV431B 2.5VPower ManagementCharge PumpSwitching RegulatorExample application block diagram.RS-232I 2C BusMicrocontrollerwith Integrated12-/16-Bit ADCand LCD DriverPower ManagementLDO RegulatorIrDA3.3VKeypadEEPROMLCD DisplayDC MotorExample application block diagram.Medical Applications Guide Texas Instruments 2Q 2007