AP7363 Datasheet, PDF (8/14 Pages) Diodes Incorporated – 1.5A, LOW QUIESCENT CURRENT, FAST TRANSIENT ULTRA-LOW DROPOUT LINEAR REGULATOR

AP7363
1.5A, LOW QUIESCENT CURRENT, FAST TRANSIENT
ULTRA-LOW DROPOUT LINEAR REGULATOR
Application Note (cont.)
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.
Stability and Phase Margin
Any regulator which operates using a feedback loop must
be compensated in such a way as to ensure adequate
phase margin, which is defined as the difference between
the phase shift and -180 degrees at the frequency where
the loop gain crosses unity (0 dB). For most LDO
regulators, the ESR of the output capacitor is required to
create a zero to add enough phase lead to ensure stable
operation. The AP7362 has a internal compensation
circuit which maintains phase margin regardless of the
ESR of the output capacitor, any type of capacitos can be
used.
Below two charts show the gain/phase plot of the
AP7362 with an output of 1.2V, 10 μF ceramic output
capacitor, delivering 1.5A load current and no load. It can
be seen the phase margin is about 90° (which is very
stable).
120
100 PHASE
80
60 _GAIN
40
20
0
-20
-40
-60
-80
-100
V_IN=2.7V
V_OUT=1.2V
I_L=1.5A
C_OUT=10μF CER
-120
100
1k
10k 100k
FREQUENCY(Hz)
140
120
100
80
60
40
20
0
-20
-40
-60
-80
1M
Gain-Bandwidth Plot for 1.5A Load
120
100
80 ^PHASE
60 _GAIN
40
20
0
-20
-40
-60
-80
-100
V_IN=2.7V
V_OUT=1.2V
I_L=0A
C_OUT=10μF CER
-120
100
1k
10k
100k
140
120
100
80
60
40
20
0
-20
-40
-60
-80
1M
FREQUENCY(Hz)
Gain-Bandwidth Plot for no Load
Short Circuit 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 prevent over-
current and to protect the regulator from damage due to
overheating.
Thermal Shutdown Protection
Thermal protection disables the output when the junction
temperature rises to approximately +170°C, allowing the
device to cool down. When the junction temperature
reduces to approximately +160°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.
Low Quiescent Current
The AP7362, consuming only around 0.5mA for all input
range, provides great power saving in portable and low
power applications.
AP7363
Document number: DS35059 Rev. 2 - 2
8 of 14
www.diodes.com
July 2011
© Diodes Incorporated