AME1505 Datasheet, PDF (6/12 Pages) Analog Microelectronics – High Power BiPolar Linear LDO

AME, Inc.
AME1505
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 + _R1 ) + I_ADJ x R2
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.
V_IN
V_CONTROL
OUT
V_OUT
V_POWER
SENSE
ADJ
C₁
R1
V_REF
I_ADJ
R2
V_OUT
=
V_REF
(1+R2 )
R1
+
I_ADJ
x
R2
High Power BiPolar Linear LDO
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_CONTROL
V_POWER
V_CONTROL
V_POWER
ADJ
OUT
SENSE
R_P
Parasitic
Line Resistance
R1
(Connect R1 to case) _RL
R2
Connect
R2 to load
6