SUPPLY VOLTAGE TRANSIENTS
High supply voltage transients can cause a reset
output signal disturbation.
For supply voltage greater than 8V the circuit
shows a high immunity of the reset output against
supply transients of more than 100V/µs.
For supply voltage lower than 8V, supply tran-
sients of more than 0.4V/µs. can cause a reset
Foldback Characteristics Of Vo
The L4925 is a monolithic integrated voltage
regulator, based on the STM modular voltage
regulator approach. Several outstanding features
and auxiliary functions are implemented to meet
the requirements of supplying microprocessor
systems in automotive applications.
Nevetrheless, it is suitable also in other applica-
tions where the present functions are required.
The modular approach of this device allows to get
easily also other features and functions when re-
The voltage regulator uses an Isolated Collector
Vertical PNP transistor as a regulating element.
With this structure very low dropout voltage at
currents up to 500mA is obtained.
Figure 1: Output Voltage vs. Input Voltage
The dropout operation of the standby regulator is
maintained down to 3V input supply voltage. The
output voltage is regulated up to the transient in-
put supply voltage of 35V. With this feature no
functional interruption due to overvoltage pulses
The typical curve showing the standby output
voltage as a function of the input supply voltage is
shown in fig. 1.
The current consumption of the device (quiescent
current) is less than 250µA.
To reduce the quiescent current peak in the un-
dervoltage region and to improve the transient re-
sponse in this region, the dropout voltage is con-
The quiescent current as a function of the supply
input voltage is shown in fig. 2.
Figure 2: Quiescent Current vs. Supply Voltage