L4937 STMICROELECTRONICS [STMicroelectronics], L4937 Datasheet - Page 6

• Manufacturer Part Number: L4937
• Description: DUAL MULTIFUNCTION VOLTAGE REGULATOR
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

L4937N
6/9
Figure 1 : Output Voltage vs. Input Voltage.
Figure 2 : Quiescent Current vs. Supply Voltage.
RESET CIRCUIT
Theblock circuit diagramof the resetcircuit is shown
in fig.3. Thereset circuit supervisesthe standbyout-
put voltage. The reset threshold of 4.7V is defined
by the internal reference voltage and the standby
output divider.
The reset pulse delay time t
charge time of an external capacitor C
t
RD
=
400
200
C
T
2 A
x 2V
RD
, is defined by the
T
:
The reaction time of the reset circuit dependson the
discharge time limitation of the reset capacitor C
and is proportional to the value of C
The reaction time of the reset circuit increases the
noise immunity. In fact, if the standbyoutput voltage
drops below the reset threshold for a time shorter
than the reaction time t
occurs. The nominal reset delay is generated for
standby output voltage drops longer than the time
necessary for the complete discharging of the ca-
pacitor C
= 100nF. The typical reset output waveforms are
shown in fig.
T
. This time is typically equal to 50 s if C
RR
, no reset output variation
T
.
T
T