ISL28276_07 Datasheet, PDF (11/13 Pages) Intersil Corporation – Dual and Quad Precision Micropower Single Supply Rail-to-Rail Input and Output Precision Op Amps

ISL28276, ISL28476
Pin Descriptions
ISL28276
ISL28476
(16 LD QSOP) (16 LD QSOP)
3
1
4
2
5
3
15
4
12
5
13
6
14
7
1, 2, 8, 9, 10, 16
8, 9
10
11
12
7
13
14
15
16
6
11
PIN NAME
OUT_A
IN-_A
IN+_A
V+
IN+_B
IN-_B
OUT_B
NC
OUT_C
IN-_C
IN+_C
V-
IN+_D
IN-_D
OUT_D
EN_A
EN_B
EQUIVALENT
CIRCUIT
DESCRIPTION
Circuit 3 Amplifier A output
Circuit 1 Amplifier A inverting input
Circuit 1 Amplifier A non-inverting input
Circuit 4 Positive power supply
Circuit 1 Amplifier B non-inverting input
Circuit 1 Amplifier B inverting input
Circuit 3 Amplifier B output
No internal connection
Circuit 3 Amplifier C output
Circuit 1 Amplifier C inverting input
Circuit 1 Amplifier B non-inverting input
Circuit 4 Negative power supply
Circuit 1 Amplifier D non-inverting input
Circuit 1 Amplifier D inverting input
Circuit 3 Amplifier D output
Circuit 2
Amplifier A enable pin internal pull-down; Logic “1” selects the disabled state;
Logic “0” selects the enabled state.
Circuit 2
Amplifier B enable pin with internal pull-down; Logic “1” selects the disabled
state; Logic “0” selects the enabled state.
IN-
CIRCUIT 1
V+
IN+
V-
V+
LOGIC
PIN
V-
CIRCUIT 2
V+
OUT
V-
CIRCUIT 3
V+
CAPACITIVELY
COUPLED
ESD CLAMP
V-
CIRCUIT 4
Applications Information
Introduction
The ISL28276 and ISL28476 are Dual and Quad channel
CMOS rail-to-rail input, output (RRIO) micropower precision
operational amplifier with an enable feature. The parts are
designed to operate from single supply (2.4V to 5.0V) or dual
supply (±1.2V to ±2.5V) while drawing only 120μA of supply
current. The device has an input common mode range that
extends 10% above the positive rail and up to 100mV below
the negative supply rail. The output operation can swing
within about 4mV of the supply rails with a 100kΩ load
(reference Figures 29 through 32). This combination of low
power and precision performance makes them suitable for
solar and battery power applications.
Rail-to-Rail Input
The input common-mode voltage range of the ISL28276 and
ISL28476 is from the negative supply to 10% greater than
the positive supply without introducing additional offset
errors or degrading performance associated with a
conventional rail-to-rail input operational amplifier. 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.
The ISL28276 and ISL28476 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
11
FN6301.1
April 20, 2007