Datasheet

ADP196 Data Sheet
Rev. 0 | Page 10 of 12
APPLICATIONS INFORMATION
CAPACITOR SELECTION
Output Capacitor
The ADP196 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
more than 1 µF of output capacitance is required, increase the
input capacitance to match it.
GROUND CURRENT
The major source of ground current in the ADP196 is the internal
charge pump for the FET drive circuitry. Figure 22 shows the
typical ground current when V
EN
= V
IN
and varies from 1.8 V
to 5.5 V.
0
5
10
15
20
25
30
35
40
45
50
1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
GROUND CURRENT (µA)
V
IN
(V)
10704-023
50mA
100mA
200mA
500mA
1000mA
3000mA
Figure 22. Ground Current vs. Input Voltage (V
IN
) for Different Load Currents
ENABLE FEATURE
The ADP196 uses the EN pin to enable and disable the VOUT
pin under normal operating conditions. As shown in Figure 23,
when a rising voltage (V
EN
) on the EN pin crosses the active
threshold, VOUT turns on. When a falling voltage (V
EN
) on
the EN pin crosses the inactive threshold, VOUT turns off.
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
0 0.2 0.4 0.6 0.8 1.0 1.2
V
OUT
(V)
ENABLE VOLTAGE (V)
V
EN
FALLING
V
EN
RISING
V
OUT
AT 3.6V
10704-024
Figure 23. Typical EN Pin Operation
As shown in Figure 23, the EN pin has built-in hysteresis. The
hysteresis 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 V
IN
voltage; therefore, these thresholds vary with changing input
voltage. Figure 24 shows the typical EN active/inactive thresholds
when the input voltage varies from 1.8 V to 5.5 V.
0
0.2
0.4
0.6
0.8
1.0
1.2
1.8 2.2 2.6 3.0 3.4 3.8 4.2 4.6 5.0 5.4
ENABLE THRESHOLD (V)
INPUT VOLTAGE (V)
EN RISE
EN FALL
10704-025
Figure 24. Typical EN Thresholds vs. Input Voltage (V
IN
)