OPA314-Q1 Datasheet, PDF (19/38 Pages) Texas Instruments – 3-MHz, Low-Power, Low-Noise, RRIO, 1.8-V CMOS Operational Amplifier

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7 Detailed Description
OPA314-Q1, OPA2314-Q1, OPA4314-Q1
SLOS896B – DECEMBER 2014 – REVISED JANUARY 2017
7.1 Overview
The OPAx314-Q1 is a family of low-power, rail-to-rail input and output operational amplifiers. These devices
operate from 1.8 V to 5.5 V, are unity-gain stable, and are suitable for a wide range of general-purpose
applications. The class AB output stage is capable of driving ≤ 10-kΩ loads connected to any point between V+
and ground. The input common-mode voltage range includes both rails and allows the OPAx314-Q1 series to be
used in virtually any single-supply application. Rail-to-rail input and output swing significantly increases dynamic
range, especially in low-supply applications, and makes them ideal for driving sampling analog-to-digital
converters (ADCs).
7.2 Functional Block Diagram
V+
Reference
Current
V_IN+
V_IN-
V_BIAS1
Class AB
Control
V_O
Circuitry
V_BIAS2
V-
(Ground)
Copyright © 2017, Texas Instruments Incorporated
7.3 Feature Description
7.3.1 Operating Voltage
The OPAx314-Q1 op-amp family is fully specified and ensured for operation from 1.8 V to 5.5 V. In addition,
many specifications apply from –40°C to +125°C. Parameters that vary significantly with operating voltages or
temperature are shown in the Typical Characteristics section. Power-supply pins must be bypassed with 0.01-μF
ceramic capacitors.
7.3.2 Rail-to-Rail Input
The input common-mode voltage range of the OPAx314-Q1 family extends 200 mV beyond the supply rails. This
performance is achieved with a complementary input stage: an N-channel input differential pair in parallel with a
P-channel differential pair. The N-channel pair is active for input voltages close to the positive rail, typically (V+) –
1.3 V to 200 mV above the positive supply. The P-channel pair is on for inputs from 200 mV below the negative
supply to approximately (V+) – 1.3 V. A small transition region exists, typically (V+) – 1.4 V to (V+)
– 1.2 V, in which both pairs are on. This 200-mV transition region can vary up to 300 mV with process variation.
Thus, the transition region (both stages on) can range from (V+) – 1.7 V to (V+) – 1.5 V on the low end, up to
(V+) – 1.1 V to (V+) – 0.9 V on the high end. Within this transition region, PSRR, CMRR, offset voltage, offset
drift, and THD may be degraded compared to device operation outside this region.
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Product Folder Links: OPA314-Q1 OPA2314-Q1 OPA4314-Q1