MAX4240 Maxim, MAX4240 Datasheet - Page 13

• Manufacturer Part Number: MAX4240
• Description: The MAX4240–MAX4244 family of micropower op amps operate from a single +1
• Manufacturer: Maxim

value, based on driving the output voltage to within
50mV, 100mV, and 200mV of either power-supply rail.
For example, a MAX4241 running from a single +1.8V
supply, operating at T
within 100mV of V
load resistor to V
The same application can drive a 3.3kΩ load resistor
when terminated in V
The MAX4240–MAX4244 are unity-gain stable for loads
up to 200pF (see Load Resistor vs. Capacitive Load
graph in Typical Operating Characteristics ). Applica-
tions that require greater capacitive drive capability
should use an isolation resistor between the output and
the capacitive load (Figure 8). Note that this alternative
results in a loss of gain accuracy because R
voltage divider with the load resistor.
The MAX4240–MAX4244 family operates from either a
single +1.8V to +5.5V supply or dual ±0.9V to ±2.75V
supplies. For single-supply operation, bypass the
power supply with a 100nF capacitor to V
case GND). For dual-supply operation, both the V
Figure 8b. Pulse Response without Isolating Resistor
50mV/div
50mV/div
Power-Supply Bypassing and Layout
R
L
R
ISO
=
= NONE, R
1.8V - 0.1V
EE
______________________________________________________________________________________
CC
:
240 A
CC
L
A
and is capable of driving a 7k
= 100k , C
Driving Capacitive Loads
Single/Dual/Quad, +1.8V/10µA, SOT23,
= +25°C, can source 240µA to
/ 2 (+0.9V in this case).
100 s/div
L
= 700pF
7k to V
MAX4240-44 fig08b
EE
ISO
IN
OUT
EE
forms a
(in this
Beyond-the-Rails Op Amps
CC
and V
separate 100nF capacitors.
Good PC board layout techniques optimize perfor-
mance by decreasing the amount of stray capacitance
at the op amp’s inputs and output. To decrease stray
capacitance, minimize trace lengths by placing exter-
nal components as close as possible to the op amp.
Surface-mount components are an excellent choice.
Figure 8a Using a Resistor to Isolate a Capacitive Load from
the Op Amp
Figure 8c. Pulse Response with Isolating Resistor
EE
50mV/div
50mV/div
supplies should be bypassed to ground with
R
ISO
= 1k , R
MAX4240
MAX4241
MAX4242
MAX4243
MAX4244
L
= 100k , C
100 s/div
L
= 700pF
R
ISO
R
L
A
MAX4240-44 fig08c
V
=
R
L
R
+ R
L
ISO
C
IN
L
OUT
1
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