Rainbow Electronics MAX4334 - Manual (Page 11)

MAX4330–MAX4334
Single/Dual/Quad, Low-Power, Single-Supply,
Rail-to-Rail I/O Op Amps with Shutdown
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Rail-to-Rail Output Stage
The MAX4330–MAX4334 output stage can drive up to a
2k
Ω
load and still typically swing within 125mV of the
rails. Figure 3 shows the output voltage swing of a
MAX4331 configured as a unity-gain buffer. The operat-
ing voltage is a single +3V supply, and the input volt-
age is 3Vp-p. The output swings to within 70mV of V
EE
and 100mV of V CC , even with the maximum load
applied (2k
Ω
to mid-supply).
Driving a capacitive load can cause instability in many
op amps, especially those with low quiescent current.
The MAX4330–MAX4334 are stable for capacitive loads
up to 150pF. The Capacitive Load Stability graph in the
Typical Operating Characteristics gives the stable
operating region for capacitive vs. resistive loads.
Figures 4 and 5 show the response of the MAX4331
with an excessive capacitive load, compared with the
response when a series resistor is added between the
output and the capacitive load. The resistor improves
the circuit’s response by isolating the load capacitance
from the op amp’s output (Figure 6).
1k
1k
Figure 2. Input Protection Circuit
Figure 3. Rail-to-Rail Input/Output Voltage Range
IN 1V/div
1V/div OUT
20 µ s/div
V CC = 3V, R L = 2k Ω TO V CC / 2
Figure 4. Small-Signal Transient Response with Excessive
Capacitive Load
IN 50mV/div
50mV/div OUT
2 µ s/div
R ISO = 0 Ω , A V = +1
C L = 510pF
V CC = 3V, R L = 100k Ω