Datasheet

MAX4130–MAX4134
Single/Dual/Quad, Wide-Bandwidth, Low-Power,
Single-Supply, Rail-to-Rail I/O Op Amps
11
Maxim Integrated
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 MAX4131
connected as a voltage follower. With a +3V supply
and the load tied to ground, the output swings from
0.00V to 2.90V. The maximum output voltage swing
depends on the load, but will be within 150mV of a +3V
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 MAX4130–MAX4134 have a high tol-
erance for capacitive loads. They are stable with
capacitive loads up to 160pF. 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 isolation resistor in series with the
output (Figure 7). The resistor improves the circuit’s
phase margin by isolating the load capacitor from the
op amp’s output.
IN
TIME (1μs/div)
VOLTAGE (1V/div)
OUT
V
CC
= 3V, R
L
= 10kΩ to V
EE
Figure 3. Rail-to-Rail Input/Output Voltage Range
500
0
50
100
150
200
300
350
400
450
0.1 1 10010
LOAD RESISTANCE (kΩ)
LOAD CAPACITANCE (pF)
250
UNSTABLE
OPERATING
REGION
STABLE
OPERATING
REGION
R
L
TO V
EE
V
OUT
= V
CC
/2
Figure 4. Capacitive-Load Stability
IN
TIME (200ns/div)
VOLTAGE (50mV/div)
OUT
V
CC
= 5V
R
L
= 10kΩ
C
L
= 130pF
Figure 5. MAX4131 Small-Signal Transient Response with
Capacitive Load
Figure 6. MAX4131 Transient Response to Capacitive Load
with Isolation Resistor
IN
TIME (500ns/div)
VOLTAGE (50mV/div)
OUT
V
CC
= 5V
C
L
= 1000pF
R
S
= 39Ω