Datasheet MAX4289 (Analog Devices) - 7

1.0V Micropower, SOT23, Operational Amplifier MAX4289 POWER-SUPPLY REJECTION RATIO vs. SUPPLY VOLTAGE
90 TA = +85°C 80 RISO MAX4289 70 TA = -40°C PSRR (dB) RL CL TA = +25°C 60 50 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 R SUPPLY VOLTAGE (V) A L V = ≈ 1 RL + RISO Figure 3. PSRR vs. V Figure 4. Using a Resistor to Isolate a Capacitive Load from CC Over the Temperature Range the Op Amp
Power-Up Settling Time Power Supplies and Layout
The MAX4289 typically requires 300µs to power-up The MAX4289 operates from a single 1V to 5.5V power after V supply. Bypass the power with a 0.1µF capacitor to CC is stable. During this startup time, the output is indeterminate. The application circuit should allow for ground. this initial delay. Good layout techniques optimize performance by decreasing the amount of stray capacitance at the op
Driving Capacitive Loads
amp’s inputs and outputs. To decrease stray capaci- The MAX4289 is unity-gain stable for loads up to tance, minimize trace lengths by placing external com- 200pF. Applications that require greater capacitive- ponents close to the op amp’s pins. 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 because RISO forms a voltage-divider with the load 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.
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