The AN2577 is a premium performance 4 3/4-digit digital panel instrument which enhances Analogic’s broad line of high performance digital panel instruments. The full scale readout (±39999 count) provides a resolution of ±0.0025% with a guaranteed accuracy of ±0.005%. The input amplifier has a bipolar differential input circuit with an input impedance of 1000000000 ohms. It is protected against overvoltages up to ± 100 volts. The AN2577 is offered with either of two full-scale ranges: the ± 3.9999-volt range provides 100µV/count sensitivity; the ±399.99 millivolt range provides a 10µV/count sensitivity. The 3-phase, dual-slope A/D converter includes an automatic zero feature for long-term accuracy. The “ unknown” integration period is optimized to yield a Normal Mode Rejection Ratio (NMRR) in excess of 90dB. The entire input amplifier and A/D converter are isolated (floated) up to ±300 volts with respect to digital ground. This level of isolation yields a Common Mode Rejection Ratio (CMRR) of up to 140dB. The digital portion includes the drivers for the large LED red, planar display, and several status and control lines. Control signal inputs are included to BLANK the display, HOLD the last value, TEST the display, and to select the decimal point location. The AN2577 may be externally triggered for up to 10 conversions per second. Status signals include converter STATUS and OVERRANGE. The standard AN2577 includes a universal ac power supply for either 110Vac or 220Vac ± 20%, from 50 to 500Hz (@ 2.7 Watts). The power supply provides up to 1400 volts dc or ac peak isolation between the digital ground and ac power line, and between the analog ground and ac power line.