ADP1290

Data Sheet

APPLICATIONS INFORMATION

CAPACITOR SELECTION

Output Capacitor

The ADP1290 is designed for operation with small, space-

saving ceramic capacitors but functions with most commonly

used capacitors when the effective series resistance (ESR) value

is carefully considered. The ESR of the output capacitor affects

the response to load transients. A typical 1 µF capacitor with an

ESR of 0.1 Ω or less is recommended for good transient response.

Using a larger value of output capacitance improves the transient

response to large changes in load current.

Input Bypass Capacitor

Connecting at least 1 µF of capacitance from VIN to GND reduces

the circuit sensitivity to the PCB layout, especially when high

source impedance or long input traces are encountered. When

an output capacitance of greater than 1 µF is required, increase

the input capacitor to match it.

GROUND CURRENT

The major source for ground current in the ADP1290 is the

internal charge pump for the FET drive circuitry. Figure 21

from 2.3 V to 13.2 V.

0

5

10

15

20

25

2

4

6

8

10

12

14

INPUT VOLTAGE (V)

ENABLE FEATURE

The ADP1290 uses the EN pin to enable and disable the VOUT

pin under normal operating conditions. As shown in Figure 22,

on the EN pin crosses the inactive threshold, the VOUT pin

turns off.

0

1

2

3

4

5

6

0.50

0.55

0.60

0.65

0.70

0.75

0.80

0.85

0.90

0.95

1.00

ENABLE VOLTAGE (V)

Figure 22. Typical EN Operation

As shown in Figure 22, the EN pin has hysteresis built into it.

The hysteresis prevents on/off oscillations that can occur due to

noise on the EN pin as it passes through the threshold points.

voltage; therefore, these thresholds vary with the changing input

voltage. Figure 23 shows the typical EN rising and falling

thresholds when the input voltage varies from 2.3 V to 13.2 V.

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

2

4

6

8

10

12

14

EN RISE

EN FALL

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