MAX4240EUK-T Maxim Integrated Products, MAX4240EUK-T Datasheet - Page 11

• Manufacturer Part Number: MAX4240EUK-T
• Description: Op Amps 1.8V 10uA Beyond the-Rails
• Manufacturer: Maxim Integrated Products

Specifications of MAX4240EUK-T

• Number Of Channels: 1
• Voltage Gain Db: 94 dB
• Common Mode Rejection Ratio (min): 69 dB
• Input Offset Voltage: 1.4 mV
• Operating Supply Voltage: 3 V or 5 V
• Maximum Power Dissipation: 571 mW
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Package / Case: SOT-23
• Maximum Dual Supply Voltage: +/- 2.75 V
• Minimum Operating Temperature: - 40 C

In the region where the differential input voltage
approaches 1.8V, the input resistance decreases expo-
nentially from 45MΩ to 4.4kΩ as the diode block begins
conducting. Conversely, the bias current increases with
the same curve.
The MAX4240–MAX4244 output stage can drive up to a
10kΩ load and still swing to within 40mV of the rails.
Figure 3 shows the output voltage swing of a MAX4240
configured as a unity-gain buffer, powered from a single
+2V supply voltage. The output for this setup typically
swings from (V
load.
The MAX4240–MAX4244 operate from a single +1.8V
to +5.5V supply (or dual ±0.9V to ±2.75V supplies) and
consume only 10µA of supply current per amplifier. A
high power-supply rejection ratio of 90dB allows the
amplifiers to be powered directly off a decaying battery
voltage, simplifying design and extending battery life.
The MAX4240–MAX4244 are ideally suited for use with
most battery-powered systems. Table 1 lists a variety of
typical battery types showing voltage when fresh, volt-
age at end-of-life, capacity, and approximate operating
time from a MAX4240/MAX4241, assuming nominal
conditions for both normal and shutdown modes.
Although the amplifiers are fully guaranteed over tem-
perature for operation down to a +1.8V single supply,
even lower-voltage operation is possible in practice.
Figures 4 and 5 show the PSRR and supply current as
a function of supply voltage and temperature.
The MAX4240–MAX4244 typically require 200µs to
power up after V
the output is indeterminant. The application circuit
should allow for this initial delay.
The MAX4241 (single) and MAX4243 (dual) feature a
low-power shutdown mode. When the shutdown pin
(SHDN) is pulled low, the supply current drops to 1µA
per amplifier, the amplifier is disabled, and the outputs
enter a high-impedance state. Pulling SHDN high or
leaving it floating enables the amplifier. Take care to
ensure that parasitic leakage current at the SHDN pin
does not inadvertently place the part into shutdown
mode when SHDN is left floating. Figure 6 shows the
output voltage response to a shutdown pulse. The logic
threshold for SHDN is always referred to V
__________Applications Information
EE
CC
Power-Supply Considerations
+ 6mV) to (V
______________________________________________________________________________________
is stable. During this start-up time,
Single/Dual/Quad, +1.8V/10µA, SOT23,
Rail-to-Rail Output Stage
Power-Up Settling Time
CC
- 8mV) with a 100kΩ
Shutdown Mode
CC
/ 2 (not to
Beyond-the-Rails Op Amps
Figure 3. Rail-to-Rail Input/Output Voltage Range
Figure 4. Power-Supply Rejection Ratio vs. Supply Voltage
Figure 5. Supply Current vs. Supply Voltage
1V/div
1V/div
100
10
12
90
80
70
60
8
6
4
2
0
1.0
1.0
R
V
f
T
IN
L
IN
A
T
A
= 100k TIED TO V
= 1kHz
= +85°C
= 2.0V
= +85°C
1.2
T
1.2
A
= +25°C
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
T
A
1.4
1.4
= +25°C
200 s/div
EE
1.6
1.6
T
A
= -40°C
T
A
= -40°C
1.8
MAX4240-44 fig03
1.8
2.0
2.0
OUT
IN
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