Datasheet

ADC1173
www.ti.com SNAS025F –FEBRUARY 1999–REVISED APRIL 2013
Because of resistor tolerances, the reference voltages can vary by as much as 6%. Choose an amplifier that can
drive a dynamic capacitance (see text).
Figure 26. Simple, Low Component Count, Self -Bias Reference application.
The reference self-bias circuit of is very simple and performance is adequate for many applications. Superior
performance can generally be achieved by driving the reference pins with a low impedance source.
By forcing a little current into or out of the top and bottom of the ladder, as shown in , the top and bottom
reference voltages can be trimmed. The resistive divider at the amplifier inputs can be replaced with
potentiometers. The LMC662 amplifier shown was chosen for its low offset voltage and low cost. Note that a
negative power supply is needed for these amplifiers if their outputs are required to go slightly negative to force
the required reference voltages.
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