Datasheet AD8556 (Analog Devices) - 3

Data Sheet AD8556 GENERAL DESCRIPTION
The AD8556 is a zero-drift, sensor signal amplifier with In addition to extremely low input offset voltage, low input offset digitally programmable gain and output offset. Designed to voltage drift, and very high dc and ac CMRR, the AD8556 also easily and accurately convert variable pressure sensor and includes a pull-up current source at the input pins and a pul - strain bridge outputs to a wel -defined output voltage range, down current source at the VCLAMP pin, which allows open the AD8556 accurately amplifies many other differential or wire and shorted wire fault detection. A low-pass filter function single-ended sensor outputs. The AD8556 uses the Analog is implemented via a single low cost external capacitor. Output Devices, Inc. patented low noise, auto-zero and DigiTrim® clamping set via an external reference voltage allows the AD8556 technologies to create an incredibly accurate and flexible to drive lower voltage ADCs safely and accurately. signal processing solution in a very compact footprint. When used in conjunction with an ADC referenced to the same Gain is digitally programmable in a wide range from 70 to supply, the system accuracy becomes immune to normal supply 1280 through a serial data interface. Gain adjustment can voltage variations. Output offset voltage can be adjusted with a be fully simulated in-circuit and then permanently pro- resolution of better than 0.4% of the difference between VDD grammed with reliable polyfuse technology. Output offset and VSS. A lockout trim after gain and offset adjustment further voltage is also digitally programmable and is ratiometric to ensures field reliability. the supply voltage. The AD8556 also features internal EMI The AD8556 is fully specified from −40°C to +140°C. filters on the VNEG, VPOS, FILT and VCLAMP pins. Operating from single-supply voltages of 4.5 V to 5.5 V, the AD8556 is offered in the 8-lead SOIC_N and 4 mm × 4 mm 16-lead LFCSP_WQ. Rev. B | Page 3 of 27 Document Outline FEATURES APPLICATIONS FUNCTIONAL BLOCK DIAGRAM TABLE OF CONTENTS REVISION HISTORY GENERAL DESCRIPTION SPECIFICATIONS ELECTRICAL SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS THERMAL RESISTANCE ESD CAUTION PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS TYPICAL PERFORMANCE CHARACTERISTICS THEORY OF OPERATION GAIN VALUES OPEN WIRE FAULT DETECTION SHORTED WIRE FAULT DETECTION FLOATING VPOS, VNEG, OR VCLAMP FAULT DETECTION DEVICE PROGRAMMING Digital Interface Initial State Simulation Mode Programming Mode Parity Error Detection Read Mode Sense Current Programming Procedure Determining Optimal Gain and Offset Codes EMI/RFI PERFORMANCE OUTLINE DIMENSIONS ORDERING GUIDE