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AP7365 View Datasheet(PDF) - Diodes Incorporated.

Part Name
Description
Manufacturer
AP7365 Datasheet PDF : 20 Pages
First Prev 11 12 13 14 15 16 17 18 19 20
AP7365
600mA, Low Quiescent Current, Fast Transient
Low Dropout Linear Regulator
Application Note
Input Capacitor
A 1μF ceramic capacitor is recommended between IN and
GND pins to decouple input power supply glitch and noise.
The amount of the capacitance may be increased without
limit. This input capacitor must be located as close as
possible to the device to assure input stability and reduce
noise. For PCB layout, a wide copper trace is required for
both IN and GND pins. A lower ESR capacitor type allows
the use of less capacitance, while higher ESR type
requires more capacitance.
Output Capacitor
The output capacitor is required to stabilize and improve
the transient response of the LDO. The AP7365 is stable
with very small ceramic output capacitors. Using a ceramic
capacitor value that is at least 1μF with ESR > 15mon
the output ensures stability. Higher capacitance values
help to improve line and load transient response. The
output capacitance may be increased to keep low
undershoot and overshoot. Output capacitor must be
placed as close as possible to OUT and GND pins.
Region of Stable COUT ESR vs. Load Current
100
Unstable Range
10
1
Stable Range
0.1
VIN=4.3V
CIN=COUT=1μF
0.01
0.001
0
Unstable Range
100 200 300 400 500 600
Load Current (mA)
Adjustable Operation
The AP7365 provides output voltage from 0.8V to 5.0V
through external resistor divider as shown below.
V IN
IN
OUT
AP7365
R1
1uF
Enable EN
ADJ
GND
R2
VOUT
1uF
The output voltage is calculated by:
VOUT
=
VREF ⎜⎜⎝⎛1 +
R1
R2
⎟⎟⎠⎞
Where VREF=0.8V (the internal reference voltage)
Rearranging the equation will give the following that is
used for adjusting the output to a particular voltage:
R1
=
R2⎜⎜⎝⎛
VOUT
VREF
1⎟⎟⎠⎞
To maintain the stability of the internal reference voltage,
R2 need to be kept smaller than 80kΩ.
No Load Stability
Other than external resistor divider, no minimum load is
required to keep the device stable. The device will remain
stable and regulated in no load condition.
ON/OFF Input Operation
The AP7365 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 voltage
thresholds listed in the Electrical Characteristics section
under VIL and VIH.
Current Limit Protection
When output current at OUT pin is higher than current limit
threshold, the current limit protection will be triggered and
clamp the output current to approximately 1.4A to prevent
over-current and to protect the regulator from damage due
to overheating.
Short Circuit Protection
When OUT pin is short-circuit to GND, short circuit
protection will be triggered and clamp the output current to
approximately 240mA. This feature protects the regulator
from over-current and damage due to overheating.
Thermal Shutdown Protection
Thermal protection disables the output when the
junction temperature rises to approximately +145°C,
allowing the device to cool down. When the junction
temperature reduces to approximately +130°C the
output circuitry is enabled again. Depending on
power dissipation, thermal resistance, and ambient
temperature, the thermal protection circuit may cycle on
and off. This cycling limits the heat dissipation of the
regulator, protecting it from damage due to overheating.
AP7365
Document number: DS32260 Rev. 2 - 2
11 of 20
www.diodes.com
September 2010
© Diodes Incorporated

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