CM1117F
1A L
OW
D
ROPOUT
V
OLTAGE
R
EGULATOR
Application Hints
Like any linear voltage regulator, CM1117F requires
external capacitors to ensure stability. The external
capacitors must be carefully selected to ensure
performance.
Thermal Considerations
It is important that the thermal limit of the package is
not exceeded.
The CM1117F has built-in thermal
protection. When the thermal limit is exceeded, the IC
will enter protection, and V
OUT
will be pulled to ground.
The power dissipation for a given application can be
calculated as following:
The power dissipation (P
D
) is
P
D
= I
OUT
* [V
IN
– V
OUT
]
The thermal limit of the package is then limited to
It must be
P
D(MAX)
= [T
J
– T
A
]/Θ
JA
where T
J
is the junction
temperature, TA is the ambient temperature, and
Θ
JA
is
around 136°C/W for CM1117F. CM1117F is designed
to enter thermal protection at 125°C. For example, if
T
A
is 25°C then the maximum P
D
is limited to about
0.9W. In other words, if I
OUT(MAX)
= 0.5A, then [V
IN
–
V
OUT
] cannot exceed 1.8V.
Input Capacitor
An input capacitor of at least 10μF is required.
Ceramic or Tantalum can be used. The value can be
increase without upper limit.
Output Capacitor
An output capacitor is required for stability.
placed no more than 1 cm away from the V
OUT
pin, and
connected directly between V
OUT
and GND pins. The
minimum value is 22μF but may be increase without
limit.
2007/11/06 Rev1.3
Champion Microelectronic Corporation
Page 5
CHAMP [ CHAMPION MICROELECTRONIC CORP. ]
