GM6250
300mA ULTRA LOW DROPOUT
POSITIVE VOLTAGE REGULATOR
Application Note
Notes on Usage
1.
2.
It is recommended to operate the GM6250 series within the stipulated absolute maximum ratings
as the IC is liable to malfunction it is operated outside the ratings.
There is a possibility of heat or oscillation as a result of the impedance present between the
power supply and the IC's input. Where impedance is greater 10Ω, it is recommend to use a
capacitor (C
IN
) of at least 1µF at the input terminal.
With a large output current, operations can be stabilized by increasing capacitor size (C
IN
). If C
IN
is
too
small and capacitance of (C
L
) is increased, there is a possibility of oscillation due to input
impedance. In such case, operation can be stabilized by either increasing the size of C
IN
or
decreasing the size of C
L
.
Please ensure the output current (I
OUT
) is less than Pd ÷ (V
IN
- V
OUT
) and does not exceed the
stipulated continuous for total power dissipation value (Pd) for the package.
3.
4.
CALCULATING POWER DISSIPATION
The GM6250 series precision linear regulators include thermal shutdown and current limit circuitry to
protect the devices. However, high power regulators normally operate at high junction temperatures so
it is important to calculate the power dissipation and junction temperatures accurately to be sure that
you use and adequate heat sink.
The thermal characteristics of an IC depend four factors:
1.
2.
3.
4.
Maximum Ambient Temperature T
A
(℃)
Power Dissipation P
D
(Watts)
Maximum Junction Temperature T
J
(℃)
Thermal Resistance Junction to ambient R
JA
(℃/W)
These relationship of these four factors is expressed by equation :
T
J
= T
A
+ P
D
X R
JA
Maximum ambient temperature and power dissipation are determined by the design while the
maximum junction temperature and thermal resistance depend on the manufacturer and the package
type.
9
GM6250
V2.00
GAMMA [ GAMMA MICROELECTRONICS INC. ]
