Data Sheet

ADPL40502

analog.com

Rev. 0

12 of 17

Input Bypass Capacitor

Connecting a 1µF capacitor from VIN to GND reduces the circuit sensitivity to the PCB layout, especially when long

input traces or high source impedance are encountered. If greater than 1µF of output capacitance is required, the

input capacitor must be increased to match it. Derating of ceramic capacitors with DC voltage, temperature, and AC

signal must be considered while selecting the output capacitor. Effective capacitance can be 80% lower than the

nominal capacitor value. Derating curves are available from all major ceramic capacitor vendors.

Enable Feature

The ADPL40502 uses the EN pin to enable and disable the VOUT pin under normal operating conditions. As shown in

Figure 24, when a rising voltage on EN crosses the active threshold, VOUT turns on. When a falling voltage on EN crosses

the inactive threshold, VOUT turns off.

Figure 24. ADPL40502 Typical EN Pin Operation

As shown in Figure 24, the EN pin has hysteresis built in to prevent on and off oscillations that can occur due to noise

on the EN pin as this pin passes through the threshold points.

The EN pin active and inactive thresholds are derived from the VIN voltage. Therefore, these thresholds vary with

changing input voltage. Figure 25 shows typical EN active and inactive thresholds when the input voltage varies from

2.2V to 5.5V.

Figure 25. Typical EN Pin Thresholds vs. Input Voltage

3.0

2.5

2.0

1.5

0.5

1.0

0

0

0.5

1.0

1.5

2.0

2.5

ENABLE VOLTAGE

1200

1000

800

600

200

400

0

2.0

2.5

3.0

3.5

4.5

5.0

4.0

5.5

INPUT VOLTAGE

VEN RISE

VEN FALL