ISL28168 Datasheet, PDF (11/16 Pages) Intersil Corporation – 34μA Micro-power Single and Dual Rail-to-Rail Input-Output (RRIO) Low Input Bias Current Op Amps

Pin Descriptions
ISL28168
(6 Ld SOT-23)
ISL28268
(8 Ld SOIC)
(8 Ld MSOP)
4
2 (A)
6 (B)
ISL28168, ISL28268
PIN NAME
NC
IN-
IN- (A)
IN- (B)
FUNCTION
Not connected
inverting input
EQUIVALENT CIRCUIT
V+
IN-
IN+
V-
3
IN+
Non-inverting input
3 (A)
IN+ (A)
5 (B)
IN+ (B)
2
4
V-
Negative supply
1
OUT
Output
1 (A)
OUT (A)
7 (B)
OUT (B)
6
8
V+
Positive supply
5
EN
Chip enable
Circuit 1
See Circuit 1
V+
CAPACITIVELY
COUPLED
ESD CLAMP
V-
Circuit 2
V+
OUT
V-
Circuit 3
See Circuit 2
V+
Applications Information
Introduction
The ISL28168 is a single CMOS rail-to-rail input, output
(RRIO) operational amplifier with an enable feature. The
ISL28268 is a dual version without the enable feature. Both
devices are designed to operate from single supply (2.4V to
5.5V) or dual supplies (±1.2V to ±2.75V).
Rail-to-Rail Input/Output
Many rail-to-rail input stages use two differential input pairs,
a long-tail PNP (or PFET) and an NPN (or NFET). Severe
penalties have to be paid for this circuit topology. As the
input signal moves from one supply rail to another, the
operational amplifier switches from one input pair to the
LOGIC
PIN
V-
Circuit 3
other causing drastic changes in input offset voltage and an
undesired change in magnitude and polarity of input offset
current.
The ISL28168 and ISL28268 achieve input rail-to-rail
operation without sacrificing important precision
specifications and degrading distortion performance. The
devices’ input offset voltage exhibits a smooth behavior
throughout the entire common-mode input range. The input
bias current versus the common-mode voltage range gives
us an undistorted behavior from typically 100mV below the
negative rail and 0.25V higher than the V+ rail. The CMOS
output stage features excellent drive capability, typically
swinging to within 6mV of either rail with a 100kΩ load.
11
FN6378.2
September 13, 2007