Power-Up Settling Time

The MAX4289 typically requires 300µs to power-up

is indeterminate. The application circuit should allow for

this initial delay.

Driving Capacitive Loads

The MAX4289 is unity-gain stable for loads up to

200pF. Applications that require greater capacitive-

drive capability should use an isolation resistor

between the output and the capacitive load (Figure 4).

Note that this solution results in a loss of gain accuracy

resistor.

Using the MAX4289 as a Comparator

Although optimized for use as an operational amplifier,

the MAX4289 can also be used as a rail-to-rail I/O com-

parator (Figure 5). External hysteresis can be used to

minimize the risk of output oscillation. The positive feed-

back circuit, shown in Figure 5, causes the input thresh-

old to change when the output voltage changes state.

Power Supplies and Layout

The MAX4289 operates from a single 1V to 5.5V power

supply. Bypass the power with a 0.1µF capacitor to

ground.

Good layout techniques optimize performance by

decreasing the amount of stray capacitance at the op

amp’s inputs and outputs. To decrease stray capaci-

tance, minimize trace lengths by placing external com-

ponents close to the op amp’s pins.

1.0V Micropower, SOT23, Operational Amplifier

_______________________________________________________________________________________

7

50

60

70

80

90

POWER-SUPPLY REJECTION RATIO

vs. SUPPLY VOLTAGE

SUPPLY VOLTAGE (V)

0.8

1.1

1.2

0.9

1.0

1.3

1.4

1.5

°C

°C

°C

≈ 1

MAX4289

Figure 4. Using a Resistor to Isolate a Capacitive Load from

the Op Amp