AME1117_07 Datasheet, PDF (10/19 Pages) Analog Microelectronics – 1A Low Dropout Positive Voltage Regulator

AME, Inc.
AME1117
n Application Description
1. Output Voltage Adjustment
Like most regulators, the AME1117 regulates the out-
put by comparing the output voltage to an internally gen-
erated reference voltage. On the adjustable version, the
V_REF is available externally as 1.25V between V_OUT and
ADJ. The voltage ratio formed by R1 and R2 should be
set to conduct 10mA (minimum output load). The output
voltage is given by the following equation:
R2
V_OUT = V_REF ( 1 + _R1 ) + I_ADJ x R2
On fixed versions of AME1117, the voltage divider is
provided internally.
V_IN
IN
OUT
V_OUT
ADJ
C₁
I_ADJ
55µA
V_REF
R1
R2
V_OUT
=
V_REF
(1+R2 )
R1
+
I_ADJ
x
R2
2. Thermal Protection
AME1117 has thermal protection which limits junction
temperature to 150^oC. However, device functionality is
only guaranteed to a maximum junction temperature of
+125^oC.
The power dissipation and junction temperature for
AME1117 is given by
P_D = (V_IN - V_OUT) x I_OUT
T_JUNCTION = T_AMBIENT + ( P_D x θ_JA)
Note: T_JUNCTION must not exceed 125^oC
1A Low Dropout
Positive Voltage Regulator
3. Current Limit Protection
AME1117 is protected against overload conditions. Cur-
rent protection is triggered at typically 1.5A.
4. Stability and Load Regulation
AME1117 requires a capacitor from V to GND to pro-
OUT
vide compensation feedback to the internal gain stage.
This is to ensure stability at the output terminal. Typi-
cally, a 10µF tantalum or 50µF aluminum electrolytic is
sufficient.
(Note: It is important that the ESR for this capacitor does not ex-
ceed 0.5Ω.)
The output capacitor does not have a theoretical upper
limit and increasing its value will increase stability. C
OUT
= 100µF or more is typical for high current regulator de-
sign.
For the adjustable version, the best load regulation is
accomplished when the top of the resistor divider (R1) is
connected directly to the output pin of the AME1117.
When so connected, R_P is not multiplied by the divider
ratio.
For fixed output versions, the top of R1 is internally
connected to the output. The ground pin can be connected
to the low side of the load in order to eliminate ground
loop errors.
V_IN
IN
OUT
R_P
Parasitic
Line Resistance
ADJ
R1
(Connect R1 to case) _RL
R2
Connect
R2 to load
10
Rev.S.02