L4949ED-E, L4949EP-E

Application information

Doc ID 16823 Rev 1

11/19

present functions are required. The modular approach of this device allows to get easily also

other features and functions when required.

3.3

Voltage regulator

The voltage regulator uses an Isolated Collector Vertical PNP transistor as a regulating

element.

Figure 4.

With this structure very low dropout voltage at currents up to 100mA is obtained. The

dropout operation of the standby regulator is maintained down to 3V input supply voltage.

The output voltage is regulated up to the transient input supply voltage of 40V. With this

feature no functional interruption due to overvoltage pulses is generated. The typical curve

showing the standby output voltage as a function of the input supply voltage is shown in

Figure 5. The current consumption of the device (quiescent current) is less than 300 µA.

To reduce the quiescent current peak in the undervoltage region and to improve the

transient response in this region, the dropout voltage is controlled, the quiescent current as

a function of the supply input voltage is shown in Figure 6.