Datasheet

Figure 3. Rail-to-Rail Input/Output Voltage Range
Figure 4. Capacitive-Load Stability
MAX4322/MAX4323/MAX4326/MAX4327/MAX4329
Single/Dual/Quad, Low-Cost, UCSP/SOT23,
Low-Power, Rail-to-Rail I/O Op Amps
10 ______________________________________________________________________________________
IN
400ns/div
VOLTAGE (50mV/div)
OUT
A
V
= +1
C
L
= 500pF
Figure 5. Small-Signal Transient Response with
Capacitive Load
IN
400ns/div
VOLTAGE (50mV/div)
OUT
A
V
= +1
C
L
= 1000pF
R
S
= 39Ω
Figure 6. Transient Response to Capacitive Load with
Isolation Resistor
IN
2µs/div
VOLTAGE (1V/div)
OUT
V
CC
= 3V
A
V
= +1
10,000
100
100 1k 100k10k
RESISTIVE LOAD (
Ω)
CAPACITIVE LOAD (pF)
1000
UNSTABLE
REGION
R
L
TO V
EE
V
OUT
= V
CC
/ 2
Rail-to-Rail Output Stage
The minimum output voltage is within millivolts of
ground for single-supply operation where the load is
referenced to ground (V
EE
). Figure 3 shows the input
voltage range and output voltage swing of a MAX4322
connected as a voltage follower. With a 3V supply and
the load tied to ground, the output swings from 0 to
2.90V. The maximum output voltage swing depends on
the load, but is within 350mV of a 5V supply, even with
the maximum load (500Ω to ground).
Driving a capacitive load can cause instability in most
high-speed op amps, especially those with low quies-
cent current. The MAX4322/MAX4323/MAX4326/
MAX4327/MAX4329 have a high tolerance for capaci-
tive loads. They are stable with capacitive loads up to
500pF. Figure 4 gives the stable operating region for
capacitive loads. Figures 5 and 6 show the response
with capacitive loads and the results of adding an iso-
lation resistor in series with the output (Figure 7). The
resistor improves the circuit’s phase margin by isolat-
ing the load capacitor from the op amp’s output.
Power-Up and Shutdown Mode
The MAX4322/MAX4323/MAX4326/MAX4327/MAX4329
amplifiers typically settle within 1µs after power-up.
I =
V - 1.8V
2k
BIAS
DIFF
Ω