Datasheet

Application information L5150CJ / L5150CS
14/34 Doc ID 15542 Rev. 15
3 Application information
3.1 Voltage regulator
The voltage regulator uses a p-channel mos transistor as a regulating element. With this
structure a very low dropout voltage at current up to 150 mA is obtained. The output voltage
is regulated up to input supply voltage of 40 V. The high-precision of the output voltage (2%)
is obtained with a pre-trimmed reference voltage. The voltage regulator automatically
adapts its own quiescent current to the output current level. In light load conditions the
quiescent current goes to 55 µA only (low consumption mode). This procedure features a
certain hysteresis on the output current (see Figure 7). Short-circuit protection to GND and a
thermal shutdown are provided.
Figure 21. Application schematic
The input capacitor µF is necessary as backup supply for negative pulses which
may occur on the line. The second input capacitor nF is needed when the C
1
is too
distant from the V
S
pin and it compensates smooth line disturbances. The C
0
ceramic
capacitor, connected to the output pin, is for bypassing to GND the high-frequency noise
and it guarantees stability even during sudden line and load variations. Suggested value is
nF?with .
Stability region is reported in Figure 22.
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C
1
100≥
C
2
220≥
C
0
220=
ESR 100≥
mΩ