l4937npd STMicroelectronics, l4937npd Datasheet - Page 6

• Manufacturer Part Number: l4937npd
• Description: Dual 5v Multifunction Voltage Regulator
• Manufacturer: STMicroelectronics

L4937NPD
Figure 2 : QuiescentCurrent vs. Supply Voltage.
Figure 3 : Programmable Output 2 Voltage with External Resistors.
RESET CIRCUIT
Theblockcircuit diagramof thereset circuit is shown
in fig.4. The resetcircuit 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
6/9
t
RD
=
200
400
C
T
2 A
x 2V
RD
, is defined by the
T
:
The reactiontime 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 standbyoutputvoltage
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
C
shown in fig. 5.
T
= 100nF.The typical reset output waveforms are
T
. This time is typically equal to 50 s if
RR
, no reset output variation
T
.
T