Datasheet

Reference

Current

V+

IN-

IN+

(Ground)

BIAS2

BIAS1

Class AB

Control

Circuitry

OPA314

OPA2314

OPA4314

SBOS563F –MAY 2011–REVISED AUGUST 2013

www.ti.com

APPLICATION INFORMATION

The OPA314 is a family of low-power, rail-to-rail input and output operational amplifiers specifically designed for

portable applications. These devices operate from 1.8 V to 5.5 V, are unity-gain stable, and 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

OPA314 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).

The OPA314 features 3-MHz bandwidth and 1.5-V/μs slew rate with only 150-μA supply current per channel,

providing good ac performance at very low power consumption. DC applications are also well served with a very

low input noise voltage of 14 nV/√Hz at 1 kHz, low input bias current (0.2 pA), and an input offset voltage of

0.5 mV (typical).

OPERATING VOLTAGE

The OPA314 series op amps are 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 graphs. Power-supply pins should be bypassed with 0.01-

μF ceramic capacitors.

RAIL-TO-RAIL INPUT

The input common-mode voltage range of the OPA314 series 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, as shown in Figure 33. 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, while the P-channel pair is on for inputs

from 200 mV below the negative supply to approximately (V+) – 1.3 V. There is a small transition region, 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.

Figure 33. Simplified Schematic

Product Folder Links: OPA314 OPA2314 OPA4314