Datasheet

OPA705, 2705, 4705
8
SBOS182A
APPLICATIONS INFORMATION
OPA705 series op amps can operate on 160µA quiescent
current from a single (or split) supply in the range of 4V to
12V (±2V to ±6V), making them highly versatile and easy
to use. The OPA705 is unity-gain stable and offers 1MHz
bandwidth and 0.6V/µs slew rate.
Rail-to-rail input and output swing helps maintain dynamic
range, especially in low supply applications. Figure 1 shows
the input and output waveforms for the OPA705 in unity-
gain configuration. Operation is from a ±5V supply with a
100kΩ load connected to V
S
/2. The input is a 10Vp-p
sinusoid. Output voltage is approximately 10Vp-p.
Power-supply pins should be bypassed with 1000pF ceramic
capacitors in parallel with 1µF tantalum capacitors.
OPERATING VOLTAGE
OPA705 series op amps are fully specified and guaranteed
from +4V to +12V over a temperature range of –40ºC to
+85ºC. Parameters that vary significantly with operating volt-
ages or temperature are shown in the Typical Characteristics.
RAIL-TO-RAIL INPUT
The input common-mode voltage range of the OPA705 series
extends 300mV beyond the supply rails at room temperature.
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 2. The N-channel pair is
active for input voltages close to the positive rail, typically
(V+) – 2.0V to 300mV above the positive supply, while the P-
channel pair is on for inputs from 300mV below the negative
supply to approximately (V+) – 1.5V. There is a small
transition region, typically (V+) – 2.0V to (V+) – 1.5V, in
which both pairs are on. This 500mV transition region can
vary ±100mV with process variation. Thus, the transition
region (both stages on) can range from (V+) – 2.1V to (V+)
– 1.4V on the low end, up to (V+) – 1.9V to (V+) – 1.6V on
the high end. Within the 500mV transition region PSRR,
CMRR, offset voltage, and offset drift, and THD may vary
compared to operation outside this region.
FIGURE 2. Simplified Schematic.
FIGURE 1. Rail-to-Rail Input and Output.
Input
Output (inverted on scope)
2.0V/div
G = +1, V
S
= ±5V
200µs/div
V
O
V–
V+
V
IN
+
V
IN
–