The Intersil HI7191 is a monolithic instrumentation, sigma
delta A/D converter which operates from ±5V supplies. Both
the signal and reference inputs are fully differential for
maximum flexibility and performance. An internal
Programmable Gain Instrumentation Amplifier (PGIA)
provides input gains from 1 to 128 eliminating the need for
external pre-amplifiers. The on-demand converter
auto-calibrate function is capable of removing offset and gain
errors existing in external and internal circuitry. The on-board
user programmable digital filter provides over 120dB of
60/50Hz noise rejection and allows fine tuning of resolution
and conversion speed over a wide dynamic range. The
HI7190 and HI7191 are functionally the same device, but the
HI7190 has tighter linearity specs.
The HI7191 contains a serial I/O port and is compatible with
most synchronous transfer formats including both the
Motorola 6805/11 series SPI and Intel 8051 series SSR
protocols. A sophisticated set of commands gives the user
control over calibration, PGIA gain, device selection, standby
mode, and several other features. The On-chip Calibration
Registers allow the user to read and write calibration data.

Features
• 20-Bit Resolution with No Missing Code
• 0.0015% Integral Non-Linearity (Typ)
• 20mV to ±2.5V Full Scale Input Ranges
• Internal PGIA with Gains of 1 to 128
• Serial Data I/O Interface, SPI Compatible
• Differential Analog and Reference Inputs
• Internal or System Calibration
• 120dB Rejection of 60/50Hz Line Noise
• Settling Time of 4 Conversions (Max) for a Step Input
• Pb-Free Plus Anneal Available (RoHS Compliant)

Applications
• Process Control and Measurement
• Industrial Weight Scales
• Part Counting Scales
• Laboratory Instrumentation
• Seismic Monitoring
• Magnetic Field Monitoring