Datasheet

MAX4238/MAX4239
Output Overload Recovery
Autozeroing amplifiers typically require a substantial
amount of time to recover from an output overload. This
is due to the time it takes for the null amplifier to correct
the main amplifier to a valid output. The MAX4238/
MAX4239 require only 3.3ms to recover from an output
overload (see Electrical Characteristics and Typical
Operating Characteristics).
Shutdown
The MAX4238/MAX4239 feature a low-power (0.1µA)
shutdown mode. When SHDN is pulled low, the clock
stops and the device output enters a high-impedance
state. Connect SHDN to V
CC
for normal operation.
Applications Information
Minimum and Maximum Gain
Configurations
The MAX4238 is a unity-gain stable amplifier with a gain-
bandwidth product (GBWP) of 1MHz. The MAX4239 is
decompensated for a GBWP of 6.5MHz and is stable with
a gain of 10V/V. Unlike conventional operational ampli-
fiers, the MAX4238/MAX4239 have a maximum gain
specification. To maintain stability, set the gain of the
MAX4238 between A
V
= 1000V/V to 1V/V, and set the
gain of the MAX4239 between A
V
= 6700V/V and 10V/V.
ADC Buffer Amplifier
The low offset, fast settling time, and 1/f noise cancella-
tion of the MAX4238/MAX4239 make these devices
ideal for ADC buffers. The MAX4238/MAX4239 are well
suited for low-speed, high-accuracy applications such
as strain gauges (see Typical Application Circuit).
Error Budget Example
When using the MAX4238/MAX4239 as an ADC buffer,
the temperature drift should be taken into account when
determining the maximum input signal. With a typical off-
set drift of 10nV/°C, the drift over a 10°C range is 100nV.
Setting this equal to 1/2LSB in a 16-bit system yields a
full-scale range of 13mV. With a single 2.7V supply, an
acceptable closed-loop gain is A
V
= 200. This provides
sufficient gain while maintaining headroom.
Chip Information
TRANSISTOR COUNT: 821
PROCESS: BiCMOS
Ultra-Low Offset/Drift, Low-Noise,
Precision SOT23 Amplifiers
8 _______________________________________________________________________________________
OUT
N.C.GND
1
2
8
7
N.C.
V
CC
IN-
IN+
SHDN
SO
TOP VIEW
3
4
6
5
MAX4238/
MAX4239
MAX4238/
MAX4239
GND
IN-IN+
16V
CC
5 SHDN
OUT
SOT23
2
34
Pin Configurations