ncv4949a ON Semiconductor, ncv4949a Datasheet - Page 8

• Manufacturer Part Number: ncv4949a
• Description: Ncv4949a 100 Ma, 5.0 V, Low Dropout Voltage Regulator With Reset And Sense
• Manufacturer: ON Semiconductor

Reset Circuit
Figure 18.
threshold of 4.5 V is defined by the internal reference
voltage and standby output divider.
time of an external capacitor C
discharge time limitation of the reset capacitor C
proportional to the value of C
circuit increases the noise immunity.
†For information on tape and reel specifications,including part orientation and tape sizes, please refer to our Tape and Reel Packaging
*NCV4949A: T
Specifications Brochure, BRD8011/D.
NCV prefix is for automotive and other applications requiring site and change control.
Out
NCV4949ADR2G*
The block circuit diagram of the reset circuit is shown in
The reset circuit supervises the output voltage. The reset
The reset pulse delay time t
The reaction time of the reset circuit originates from the
Reg
1.23 V V
Device
low
22 k
ref
= --40C, T
Figure 18. Reset Circuit
t
RD
2.0 mA
=
high
C
T
T
. The reaction time of the reset
= +125C. Guaranteed by design.
2.0 mA
RD
T
x 2.0 V
:
C
Operating Temperature Range
, is defined by the charge
T
+
--
T
2.0 V
J
= --40C to +125C
ORDERING INFORMATION
T
http://onsemi.com
and is
Reset
8
marginally longer than the reaction time results in a shorter
reset delay time.
voltage drops longer than approximately 50ms. The typical
reset output waveforms are shown in Figure 19.
Sense Comparator
internal voltage reference of typical 1.23 V. The use of an
external voltage divider makes this comparator very flexible
in the application.
or after a protection diode and to provide additional
information to the microprocessor such as low voltage
warnings.
VRT + 0.1 V
Output voltage drops below the reset threshold only
The nominal reset delay time will be generated for output
The sense comparator compares an input signal with an
It can be used to supervise the input voltage either before
Reset
5.0 V
3.0 V
VRT
V
Figure 19. Typical Reset Output Waveforms
out
(Pb--Free)
Package
SOIC--8
Switch On
V
V
out1
t
in
RD
t
RR
Input Drop
t
RD
Dump
t
R
2500 Units / Tape & Reel
40
V
Overload
Shipping
Output
†
Switch Off
t