Datasheet

V
BIAS1
V
BIAS2
V
IN
+
V
IN
−
Class AB
Control
Circuitry
V
O
V
−
(Ground)
V+
Reference
Current
OPA354-Q1
OPA2354-Q1
SBOS492A –JUNE 2009–REVISED AUGUST 2009....................................................................................................................................................... www.ti.com
APPLICATION INFORMATION
The OPA354 is a CMOS, rail-to-rail I/O, high-speed, voltage-feedback operational amplifier designed for video,
high-speed, and other applications. It is available as a single or dual op amp.
The amplifier features a 100-MHz gain bandwidth, and 150 V/μs slew rate, but it is unity-gain stable and can be
operated as a +1-V/V voltage follower.
Operating Voltage
The OPA354 is specified over a power-supply range of 2.7 V to 5.5 V (±1.35 V to ±2.75 V). However, the supply
voltage may range from 2.5 V to 5.5 V (±1.25 V to ±2.75 V). Supply voltages higher than 7.5 V (absolute
maximum) can permanently damage the amplifier.
Parameters that vary over supply voltage or temperature are shown in the typical characteristics section of this
data sheet.
Rail-to-Rail Input
The specified input common-mode voltage range of the OPA354 extends 100 mV beyond the supply rails. This 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 1. The N-channel pair is active for input voltages close to the positive rail,
typically (V+) – 1.2 V to 100 mV above the positive supply, while the P-channel pair is on for inputs from 100 mV
below the negative supply to approximately (V+) – 1.2 V. There is a small transition region, typically (V+) – 1.5 V
to (V+) – 0.9 V, in which both pairs are on. This 600-mV transition region can vary ±500 mV with process
variation. Thus, the transition region (both input stages on) can range from (V+) – 2.0 V to (V+) – 1.5 V on the
low end, up to (V+) – 0.9 V to (V+) – 0.4 V on the high end.
A double-folded cascode adds the signal from the two input pairs and presents a differential signal to the class
AB output stage.
Figure 1. Simplified Schematic
Rail-to-Rail Output
A class AB output stage with common-source transistors is used to achieve rail-to-rail output. For
high-impedance loads (> 200 Ω), the output voltage swing is typically 100 mV from the supply rails. With 10-Ω
loads, a useful output swing can be achieved while maintaining high open-loop gain. See the typical
characteristic curve Output Voltage Swing vs Output Current.
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