AME, Inc.
AME1505
High Power BiPolar Linear LDO
n
Application Description
1. Output voltage adjustment
Like most regulators, the AME1505 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 +
) + I
ADJ
x R2
R1
On fixed versions of AME1505, the voltage divider is
factory-preset internally.
2. Current limit protection
AME1505 is protected against overload conditions. Cur-
rent protection is triggered at typical 7.5A.
3. Stability and load regulation
AME1505 requires a capacitor from V
OUT
to GND to
provide 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 dose 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 AME1505.
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 low side of the load to eliminate ground loop errors.
V
IN
V
CONTROL
V
POWER
ADJ
OUT
SENSE
R1
V
OUT
C
1
I
ADJ
V
REF
V
CONTROL
V
CONTROL
V
POWER
V
POWER
SENSE
ADJ
OUT
R
P
Parasitic
Line Resistance
R2
R1
(Connect R1 to case)
R
L
V
OUT
= V
REF
(1+ R2 ) + I
ADJ
x R2
R1
R2
Connect
R2 to load
6
AME [ ANALOG MICROELECTRONICS ]
