AMS3107-20 ADMOS [Advanced Monolithic Systems], AMS3107-20 Datasheet - Page 6

• Manufacturer Part Number: AMS3107-20
• Description: 500mA LOW DROPOUT VOLTAGE REGULATOR
• Manufacturer: ADMOS [Advanced Monolithic Systems]

TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
APPLICATION NOTES
Definition of Terms
Dropout Voltage
the circuit stops to regulate against further reduction in input
voltage. Measured when the output voltage has dropped 100mV
from the nominal voltage obtained at 1V input, dropout voltage is
dependent upon load current and junction temperature.
Input Voltage
with respect to ground.
difference between the unregulated input voltage and the
regulated output voltage for which the regulator will regulate.
Line Regulation
the input voltage. The line regulation is measured under
conditions of low dissipation or by using low duty cycle pulse
testing such that the average chip temperature is not significantly
affected.
Load Regulation
load current at constant chip temperature.
Long term stability
life-test conditions after 1000 hours with maximum rated voltage
and junction temperature.
Output Noise Voltage
constant load and no input ripple, measured over a specified
frequency range.
Quiescent Current
does not contribute to the positive load current. The regulator
ground lead current.
Ripple Rejection
voltage to the peak-to-peak output ripple voltage at specified
frequency.
Temperature Stability of V
voltage for a thermal variation from room temperature to either
temperature extreme.
External capacitor
The AMS3107 series require an output capacitor of 10 F or
greater to ensure device stability. Without the capacitor the
device may oscillate.
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: The DC voltage applied to the input terminal
: The change in output voltage for a change in
: The input-output voltage differential at which
: The change in output voltage for a change in
: The ratio of the peak-to –peak input ripple
: That part of the positive input current that
: Output voltage stability under accelerated
70
60
50
40
30
20
10
0
0
4
2
1
5
3
-100
: The rms AC voltage at the output, with
Input-Output Differential
~ ~
Operation During Load Dump
O
0
: The percentage change in output
100 200 300
TIME (ms)
C
R
O
L
= 500
= 100 F
ms
400
: The voltage
500
~ ~
Most type of tantalum or electrolytic capacitor can be used in the
applications. A critical characteristic of the capacitors is an ESR
value of 5
value of this capacitor can be increased without limits.
For higher loads, the value of the capacitor should be increased,
specialy when the output voltage is set for 2.5V or less. The
AMS3107 lowest fixed output voltage value is 2.0V.
Minimum Load
In circuits using the fixed output voltage versions, minimum load
is not required. For circuits using the adjustable device, the value
of R1 and R2 should be chosen such, that a current of
approximately 40 A flows through the network. The reference
voltage (1.235V) is measured between the adjust pin and V
The output voltage can be set by the two resistors R1 and R2
using the following equation:
The value of R1 is recommended to be between 25k
and the value of R2 will set the output voltage.
1.30
1.28
1.26
1.24
1.22
1.20
1.18
1.16
1.14
1.12
1.10
V
O
Typical application circuit (adjustable output)
0
Reference Voltage
V
AMS3107 ADJUSTABLE
F
REF
3
or less and a resonant frequency above 500kHz. The
OUTPUT VOLTAGE (V)
R1
6
R1
OFF
ON
100k
R2
9
ON/OFF
12 15 18 21 24
ADJUSTABLE
GND
AMS3107
V
IN
ADJ
OUT
AMS3107
R
28k
R
1
2
+
22 F
C1
to 30 k ,
V
OUT
OUT
.