L4993

Application information

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3

Application information

Figure 24.

L4993 application schematic

Note:

The input capacitor Cs > 200nF is necessary for the smoothing of line disturbances. The

output capacitor C01 > 100nF is necessary for the stability of the regulation loop. In order to

damp output voltage oscillations during high load current surges, it is recommended put an

additional electrolytic capacitor C02 > 10µF at the output pin.

3.1

Voltage regulator

Voltage regulator uses a p-channel transistor as a regulating element. With this structure,

very low dropout voltage at current up to 500mA is obtained. The output voltage is regulated

up to transient input supply voltage of 40V. No functional interruption due to over-voltage

pulses is generated. A short circuit protection to GND is provided. The voltage regulator

watchdog functionality can be disabled by putting WEn low.

Figure 25.

Behavior of output current versus regulated voltage Vo

Thermal

protection

Watchdog

Reset

Voltage reference

-

+

Thermal

protection

Thermal

protection

Watchdog

Reset

Voltage reference

Voltage reference

Voltage reference

-

+

Vi

Vs

Vcw

Cs

Ctw

Wi

WEn

Vcr

Ctr

Gnd

Res

Vo

Vo

Vo_ref

Iout

Ishort Ilim