AP1159ADSXX Datasheet, PDF (15/19 Pages) Asahi Kasei Microsystems – 14V Input / 100mA Low voltage Output LDO Regulator

[AP1159ADS]
11.9 Stability
Linear regulators require input and output capacitors in order to maintain the regulator's loop stability. If
0.47F or larger capacitor is connected to the output side, the IC provides stable operation at any voltage
(0.9VVout_TYP1.2V). (The capacitor must be larger than 0.47F at all temperature and voltage range) If the
capacitor with high Equivalent Series Resistance (ESR) (several ohms) is used, such as tantalum capacitor
etc., the regulator may oscillate. Please select parts with low ESR. Due to the parts are uneven, please enlarge
the capacitance as much as possible. With larger capacity, the output noise decreases more. In addition, the
response to the load change, etc. can be improved. The IC won’t be damaged by enlarging the capacity.
A recommended value of the application is as follows.
Measurement circuit
Cin=Cout0.47F Ceramic Capacitance
Vin
Vout
AP1159ADS
Cin0.47F
Cnp
0.001F
Cout0.47F
GND
Output Voltage, Output Current vs. Stable Operation Area
100
100
Unstable
10
Unstable
10
1
Stable
0.1
0
20
40
60
80
100
I_OUT [mA]
Figure 3. Cout=0.47F
100
Unstable
10
1
Stable
0.1
0
20
40
60
80
100
I_OUT [mA]
Figure 4. Cout=0.68F
1
Stable
0.1
0
20
40
60
80
100
I_OUT [mA]
Figure 5. C_OUT=1.0F
Generally, a ceramic capacitor has both temperature characteristic and voltage characteristic. Please consider
both characteristics when selecting the part. The B curves are the recommend characteristics.
Rev.0.1
- 15 -
2014/09