OPA336 Datasheet, PDF (7/8 Pages) Burr-Brown (TI) – SINGLE-SUPPLY, MicroPOWER CMOS OPERATIONAL AMPLIFIERS MicroAmplifier ™ Series

APPLICATIONS INFORMATION
OPA336 series op amps are fabricated on a state-of-the-art
0.6 micron CMOS process. They are unity-gain stable and
suitable for a wide range of general purpose applications.
Power supply pins should be bypassed with 0.01µF ceramic
capacitors. OPA336 series op amps are protected against
reverse battery voltages.
OPERATING VOLTAGE
OPA336 series op amps can operate from a +2.1V to +5.5V
single supply with excellent performance. Most behavior
remains unchanged throughout the full operating voltage
range. Parameters which vary significantly with operating
voltage are shown in the typical performance curves. OPA336
series op amps are fully specified for operation from +2.3V
to +5.5V; a single limit applies over the supply range. In
addition, many parameters are guaranteed over the specified
temperature range, –40°C to +85°C.
INPUT VOLTAGE
The input common-mode range of OPA336 series op amps
extends from (V–) –0.2V to (V+) –1V. For normal opera-
tion, inputs should be limited to this range. The absolute
maximum input voltage is 300mV beyond the supplies.
Thus, inputs greater than the input common-mode range
but less than maximum input voltage, while not valid, will
not cause any damage to the op amp. Furthermore, the
inputs may go beyond the power supplies without phase
inversion (Figure 1) unlike some other op amps.
I_OVERLOAD
10mA max
V_IN
5kΩ
+5V
OPAx336
V_OUT
FIGURE 2. Input Current Protection for Voltages Exceeding
the Supply Voltage.
CAPACITIVE LOAD AND STABILITY
OPA336 series op amps can drive a wide range of capaci-
tive loads. However, all op amps under certain conditions
may become unstable. Op amp configuration, gain, and
load value are just a few of the factors to consider when
determining stability.
When properly configured, OPA336 series op amps can
drive approximately 10,000pF. An op amp in unity gain
configuration is the most vulnerable to capacitive load. The
capacitive load reacts with the op amp’s output resistance,
along with any additional load resistance, to create a pole in
the response which degrades the phase margin. In unity gain,
OPA336 series op amps perform well with a pure capacitive
load up to about 300pF. Increasing gain enhances the
amplifier’s ability to drive loads beyond this level.
One method of improving capacitive load drive in the unity
gain configuration is to insert a 50Ω to 100Ω resistor inside
the feedback loop as shown in Figure 3. This reduces ringing
with large capacitive loads while maintaining DC accuracy.
6V
V_OUT
R_S
100Ω
OPAx336
V_OUT
V_IN
C_L
R_L
FIGURE 3. Series Resistor in Unity-Gain Configuration
0V
Improves Capacitive Load Drive.
FIGURE 1. No Phase Inversion with Inputs Greater than the
Power Supply Voltage.
R_S = 100Ω, Load = 25kΩ || 1000pF, V_S = +5V
Normally, input bias current is approximately 1pA. How-
ever, input voltages exceeding the power supplies can
cause excessive current to flow in or out of the input pins.
Momentary voltages greater than the power supply can be
tolerated as long as the current on the input pins is limited
to 10mA. This is easily accomplished with an input resis-
tor as shown in Figure 2.
50µs/div
FIGURE 4. Small-Signal Step Response Using Series Re-
sistor to Improve Capacitive Load Drive.
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OPA336, 2336, 4336