ADP190/ADP191

Rev. D | Page 10 of 16

APPLICATIONS INFORMATION

GROUND CURRENT

The major source for ground current in the ADP190/ADP191 is

the 4 MΩ pull-down on the enable (EN) pin. Figure 19 shows

to 3.6 V.

2.0

1.8

1.6

1.4

1.2

1.0

0.6

0.8

350

300

250

200

150

100

50

0

LOAD (mA)

Figure 19. Ground Current vs. Load Current

As shown in Figure 20, an increase in ground current can occur

level shift circuitry as it translates an EN signal ≥ 1.1 V to

14

12

10

8

6

4

2

0

3.5

0.1 0.3 0.5 0.7 0.9 1.1 1.3 1.5 1.7 1.9 2.1 2.3 2.5 2.7

3.3

3.1

2.9

ENABLE FEATURE

The ADP190/ADP191 use the EN pin to enable and disable the

VOUT pin under normal operating conditions. As shown in

Figure 21, 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.

2.0

1.8

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0

1.2

00.4

0.5

0.6

0.7

0.1

0.2

0.3

0.8

0.9

1.0

1.1

Figure 21. Typical EN Operation

As shown in Figure 21, the EN pin has built-in hysteresis. This

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 derive from the VIN

voltage; therefore, these thresholds vary with changing input

voltage. Figure 22 shows typical EN active/inactive thresholds

when the input voltage varies from 1.1 V to 3.6 V.

1.15

1.05

0.95

0.85

0.75

0.65

0.55

0.45

0.35

EN ACTIVE

EN INACTIVE

TIMING

Turn-on delay is defined as the delta between the time that EN

reaches >1.1 V until VOUT rises to ~10% of its final value. The

ADP190/ADP191 include circuitry to set the typical 1.5 μs turn-

Figure 23, the turn-on delay is dependent on the input voltage.