AME1085 Analog Microelectronics, AME1085 Datasheet - Page 5

• Manufacturer Part Number: AME1085
• Description: 3A Low Dropout Positive Voltage Regulator
• Manufacturer: Analog Microelectronics

V
AME1085
n n n n n
IN
C
Application Description
1. Output voltage adjustment
2. Thermal protection
1
Like most regulators, the AME1085 regulates the
output by comparing the output voltage to an
internally generated reference voltage. On the
adjustable version, the V
nally as 1.25V between V
voltage ratio formed by R1 and R2 should be
set
The output voltage is given by the following
equation:
On fixed versions of AME1085, the voltage di-
vider is provided internally.
AME1085 has thermal protection which limits
junction temperature to 150
vice
mum junction temperature of +125
The power dissipation and junction temperature
for AME1085 in TO-220 package are given by
Note: T
P
T
V
V
JUNCTION
D
OUT
O U T
= (V
to conduct 10mA (minimum output load).
functionality is only guaranteed to a maxi-
Analog Microelectronics, Inc.
JUNCTION
= V
IN
= V
IN
50 A
= T
REF
- V
I
R E F
A DJ
AMBIENT
must not exceed 125
( 1 +
OUT
Figure 3
(1+ R 2
A D J
) x I
R 1
+ ( P
R2
R1
OUT
) + I
O U T
) + I
REF
D
OUT
x
ADJ
O
and ADJ. The
ADJ
is available exter-
C. However, de-
JA
x R2
)
x R2
V
O
R E F
O
C
C.
V
R 1
R 2
IN
V
O U T
3. Current limit protection
4. Stability and load regulation
IN
AME1085 is protected against overload condi-
tions. Current protection is triggered at typi-
cally 4.5A.
AME1085 requires a capacitor from V
GND to provide compensation feedback to the
internal gain stage. This is to ensure stability
at the output terminal. Typically, a 10 F tanta-
lum or 50 F aluminum electrolytic is sufficient.
Note: It is important that the ESR for this ca-
pacitor does not exceed 0.5 .
The output capacitor dose not have a theoreti-
cal upper limit and increasing its value will in-
crease stability. C
cal for high current regulator design.
For the adjustable version, the best load regu-
lation is accomplished when the top of the
resistor divider (R1) is connected directly to the
output pin of the AME1085. When so con-
nected, R
For fixed output versions, the top of R1 is in-
ternally connected to the output and ground
pin can be connected to low side of the load.
A D J
P
is not multiplied by the divider ratio.
Positive Voltage Regulator
O U T
Figure 4
OUT
= 100 F or more is typi-
(Connect R1 to case)
R 1
R 2
3A Low Dropout
Line Resistance
R2 to load
Connect
Parasitic
R
P
OUT
to
5
R
L