ISL28168_11 Datasheet, PDF (12/17 Pages) Intersil Corporation – Low Input Bias Current Op Amps

ISL28168, ISL28268
Typical Performance Curves V₊ = 5V, V_- = 0V, V_CM = 2.5V, R_L = Open (Continued)
190
N = 1000
180
170
160
150
MAX
7.5
N = 1000
7.0
6.5
6.0
MAX
140
MEDIAN
130
120
MIN
110
5.5
MEDIAN
5.0
MIN
4.5
100
-40 -20 0
20 40 60 80 100 120
4.0
-40 -20 0
20 40 60 80 100 120
TEMPERATURE (°C)
FIGURE 37. V_OUT LOW vs TEMPERATURE, V_+, V_- = ±2.5V,
R_L = 1k
TEMPERATURE (°C)
FIGURE 38. V_OUT LOW vs TEMPERATURE, V_+, V_- = ±2.5V,
R_L = 100k
45
N = 1000
40
MAX
35
MEDIAN
30
25
MIN
20
-40 -20 0
20 40 60 80 100 120
TEMPERATURE (°C)
FIGURE 39. I_O+ SHORT CIRCUIT OUTPUT CURRENT vs
TEMPERATURE, V_IN = -2.55V, R_L = 10k,
V_+, V_- = ±2.5V
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
other causing drastic changes in input offset voltage and an
undesired change in magnitude and polarity of input offset
current.
12
-20
N = 1000
-22
MAX
-24
MEDIAN
-26
MIN
-28
-30
-32
-40 -20 0
20 40 60 80 100 120
TEMPERATURE (°C)
FIGURE 40. I_O- SHORT CIRCUIT OUTPUT CURRENT vs
TEMPERATURE, V_IN = +2.55V, R_L = 10k,
V_+, V_- = ±2.5V
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.
Results of Over-Driving the Output
Caution should be used when over-driving the output for
long periods of time. Over-driving the output can occur in two
ways.
1. The input voltage times the gain of the amplifier exceeds
the supply voltage by a large value
FN6378.4
July 25, 2011