ADP165/ADP166

Data Sheet

Therefore, the capacitor chosen in this example meets

the minimum capacitance requirement of the LDO over

temperature and tolerance at the chosen output voltage.

To guarantee the performance of the ADP165/ADP166, it is

imperative that the effects of dc bias, temperature, and tolerances

on the behavior of the capacitors are evaluated for each.

ENABLE FEATURE

The ADP165/ADP166 use the EN pin to enable and disable the

VOUT pin under normal operating conditions. As shown in

Figure 39, 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.

4.5

3.5

2.5

4.0

3.0

2.0

1.5

0.5

1.0

0

0.5

0.7

0.9

1.1

1.3

1.5

EN VOLTAGE (V)

Figure 39. Typical EN Pin Operation

As shown in Figure 39, the EN pin has hysteresis built in, which

prevents on/off oscillations that can occur due to noise on the

EN pin as it passes through the threshold points.

The EN pin active/inactive thresholds are derived from the VIN

voltage. Therefore, these thresholds vary with changing input

voltage. Figure 40 shows typical EN active/inactive thresholds

when the input voltage varies from 2.2 V to 5.5 V.

1.1

1.0

0.9

0.8

0.7

0.6

0.5

2.0

2.5

3.0

3.5

EN RISE

EN FALL

4.0

4.5

5.0

INPUT VOLTAGE (V)

Figure 40. Typical EN Pin Thresholds vs. Input Voltage

The start-up behavior of the ADP165/ADP166 is shown in

Figure 41.

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0

0

4500

4000

3500

3000

2500

2000

1500

1000

500

1.2V

2.5V

3.3V

TIME (µs)

EN

Figure 41. Typical Start-Up Behavior

The shutdown behavior of the ADP165/ADP166 is shown in

Figure 42.

4.5

3.5

4.0

3.0

2.5

2.0

1.5

1.0

0.5

0

0

1000

800

600

400

200

1.2V

4.2V

TIME (µs)

EN

Figure 42. Typical Shutdown Behavior, No Load

UNDERVOLTAGE LOCKOUT (UVLO)

The ADP165/ADP166 also incorporates an internal UVLO circuit

to disable the output voltage when the input voltage is less than the

minimum input voltage rating of the regulator.

CURRENT-LIMIT AND THERMAL OVERLOAD

PROTECTION

The ADP165/ADP166 are protected against damage due to

excessive power dissipation by short-circuit and thermal overload

protection circuits. The ADP165/ADP166 are designed to limit

current when the output load reaches 320 mA (typical). When

the output load exceeds 320 mA, the output voltage is reduced

to maintain a constant current limit.

Thermal overload protection is included, which limits the

junction temperature to a maximum of 150°C (typical). Under

extreme conditions (that is, high ambient temperature and

power dissipation), when the junction temperature starts to rise

above 150°C, the output turns off, reducing the output current

to zero. When the junction temperature drops below 135°C, the

output turns on again, and the output current is restored to its

nominal value.

Rev. A | Page 16 of 23