LT1787/LT1787HV Precision, High Side Current Sense Amplifiers UFEATURESDESCRIPTIO ■ Input Offset Voltage: 75 µ V (Max) The LT®1787 is a complete micropower precision high ■ 60V Supply Operation (LT1787HV) side current sense amplifier. The LT1787 monitors bidi- ■ 12-Bit Dynamic Range rectional currents via the voltage across an external sense ■ Operating Current: 60µA resistor. A current or voltage output indicates the direction ■ User-Selectable External Sense Resistor and magnitude of the sense current. The LT1787 delivers ■ Bidirectional High Side Current Sensing greater than a 12-bit dynamic range with ultralow 40µV ■ Unidirectional or Bidirectional Output input offset voltage compared to a typical 250mV full- ■ Input Noise Filtering scale input voltage. A fixed gain of 8 is set by onboard ■ –40°C to 125°C Operating Temperature Range precision resistors. Input signal filtering is easily imple- ■ Available in 8-Lead SO and MSOP Packages mented with a capacitor between the FIL– and FIL+ pins. The LT1787HV operates from 2.5V to 60V total supply U voltage and the LT1787 operates from 2.5V to 36V total APPLICATIO S supply voltage. Both versions have a PSRR in excess of ■ 120dB. The LT1787/LT1787HV draw only 60 Battery Monitoring µA and are ■ available in 8-lead SO and MSOP packages. Power Monitoring ■ Portable Phones , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. ■ Cellular Phones ■ Portable Test/Measurement Systems ■ Battery-Operated Systems UTYPICAL APPLICATIO12-Bit Dynamic Resolution Unidirectional Output into LTC®1286 ADCInput Offset Voltage vs Supply Voltage 50 RSENSE 0.0016 I = 100A Ω TO 40 LOAD 30 1 8 2.5V TO 60V µV) FIL+ FIL– 20 LT1787HV – + 2 VS VS 7 R1 C1 10 5V 15k 1µF 3 VBIAS 6 0 DNC ROUT –10 V 4 20k 5 REF VCC CS –20 V +IN EE V LTC1286 CLK TO µP OUT –IN INPUT OFFSET VOLTAGE ( –30 D GND OUT C2 –40 1787 TA01 0.1µF LT1634-1.25 VOUT = VBIAS + (8 • ILOAD • RSENSE) –50 0 10 20 30 40 50 60 TOTAL SUPPLY VOLTAGE (V) 1787 TA01b 1787fc 1
