ADP130 Analog Devices, ADP130 Datasheet - Page 14

• Manufacturer Part Number: ADP130
• Description: 350 mA, Low VIN, Low Quiescent Current, CMOS Linear Regulator
• Manufacturer: Analog Devices

Use Equation 1 to determine the worst-case capacitance,
accounting for capacitor variation over temperature, compo-
nent tolerance, and voltage.
where:
C
TEMPCO is the worst-case capacitor temperature coefficient.
TOL is the worst-case component tolerance.
In this example, TEMPCO over −40°C to +85°C is assumed to be
15% for an X5R dielectric. TOL is assumed to be 10%, and C
= 0.94 μF at 1.8 V, as shown in Figure 36.
Substituting these values in Equation 1 yields the following:
Therefore, the capacitor chosen in this example meets the
minimum capacitance requirement of the LDO over tempera-
ture and tolerance at the chosen output voltage.
To guarantee the performance of the ADP130, it is imperative
that the effects of dc bias, temperature, and tolerances on the
behavior of the capacitors be evaluated for each application.
UNDERVOLTAGE LOCKOUT
The ADP130 has an internal undervoltage lockout circuit that
disables all inputs and the output when the input voltage is less
than approximately 2.1 V. This ensures that the ADP130 inputs
and the output behave in a predictable manner during power-up.
ENABLE FEATURE
The ADP130 uses the EN pin to enable and disable the VOUT
pin under normal operating conditions. As shown in Figure 37,
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.
ADP130
EFF
is the effective capacitance at the operating voltage.
C
C
EFF
EFF
1
2
CH1
= C
= 0.94 μF × (1 − 0.15) × (1 − 0.1) = 0.719 μF
500mV/DIV
V
C
OUT
IN
500mV
OUT
= C
EN
= 1.8V
OUT
× (1 − TEMPCO) × (1 − TOL)
Figure 37. Typical EN Pin Operation
= 1µF
CH2 500mV
M10ms
T
30%
500mV/DIV
V
OUT
A CH2
640mV
OUT
Rev. B | Page 14 of 20
(1)
As shown in Figure 37, 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 and inactive thresholds are derived from the
V
voltage. Figure 38 shows typical EN active and inactive thresholds
when the V
The ADP130 uses an internal soft start to limit the inrush current
when the output is enabled. The start-up time for the 0.8 V option
is approximately 180 µs from the time at which the EN active
threshold is crossed to when the output reaches 90% of its final
value. The start-up time depends somewhat on the output voltage
setting and increases slightly as the output voltage increases.
IN
voltage. Therefore, these thresholds vary with changing input
1.10
1.05
1.00
0.95
0.90
0.85
0.80
0.75
0.70
0.65
0.60
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
Figure 39. Typical Start-Up Time for Various Output Voltages
0
2.3
0
BIAS
100
Figure 38. Typical EN Pin Thresholds vs. Input
2.7
voltage varies from 2.3 V to 5.5 V.
200
ENABLE
3.1
3.0V
1.8V
1.2V
0.8V
300
EN INACTIVE
EN ACTIVE
3.5
400
TIME (µs)
V
BIAS
500
3.9
(V)
600
4.3
700
4.7
V
V
I
LOAD
BIAS
IN
800
= 3.6V
= 2.3V
= 10mA
5.1
900 1000
5.5