AP7217A Diodes, Inc., AP7217A Datasheet - Page 7

• Manufacturer Part Number: AP7217A
• Description: 3.3v 600ma Cmos Ldo
• Manufacturer: Diodes, Inc.

Application Note
Input Capacitor
A 1μF ceramic capacitor is recommended to connect between IN
and GND pins to decouple input power supply glitch and noise.
The amount of the capacitance may be increased without limit. A
lower ESR (Equivalent Series Resistance) capacitor allows the
use of less capacitance, while higher ESR type requires more
capacitance. This input capacitor must be located as close as
possible to the device to assure input stability and less noise. For
PCB layout, a wide copper trace is required for both IN and GND.
Output Capacitor
The output capacitor is required to stabilize and help the transient
response of the LDO. The AP7217A is designed to have
excellent transient response for most applications with a small
amount of output capacitance. The AP7217 is stable with any
small ceramic output capacitors of 1.0μF or higher value, and the
temperature coefficients of X7R or X5R type.
capacitance helps to reduce undershoot and overshoot during
transient. For PCB layout, the output capacitor must be placed as
close as possible to OUT and GND pins, and keep the leads as
short as possible.
AP7217A Rev. 1
Timing Diagram
1.6V
200mSec-TYP.
t
RP
www.diodes.com
Additional
7 of 10
ENABLE/SHUTDOWN Operation
The AP7217A is turned on by setting the EN pin high, and is
turned off by pulling it low. If this feature is not used, the EN pin
should be tied to IN pin to keep the regulator output on at all time.
To ensure proper operation, the signal source used to drive the
EN pin must be able to swing above and below the specified
turn-on/off
Characteristics section under V
Thermal Considerations
Thermal Shutdown Protection limits power dissipation in
AP7217A. When the operation junction temperature exceeds
150°C, the Over Temperature Protection circuit starts the thermal
shutdown function and turns the pass element off. The pass
element turn on again after the junction temperature cools by
40°C. For continuous operation, do not exceed absolute
maximum operation junction temperature 125°C. The power
dissipation definition in device is:
P
The maximum power dissipation depends on the thermal
resistance of IC package, PCB layout, the rate of surroundings
airflow and temperature difference between junction to ambient.
The maximum power dissipation can be calculated by following
formula :
P
Where T
125°C, T
to ambient thermal resistance.
D
D(MAX)
= (V
A
IN
= ( T
J(MAX)
is the ambient temperature and the θ
− V
voltage
J(MAX)
is the maximum operation junction temperature
OU
EN=0
EN=1
T) x I
- TA ) / θ
thresholds
OUT
3.3V 600mA CMOS LDO
VR
3.3V
0V
+ V
OUT
IL
VD
VR
V
EN
JA
and V
IN
IN
OUT
OUT
listed
x I
IH
Q
.
VD
AP7217A
Φ
Φ
©
OUT
in
Diodes Incorporated
JA
APRIL 2008
the
is the junction
Electrical