l4949dw ON Semiconductor, l4949dw Datasheet - Page 7

• Manufacturer Part Number: l4949dw
• Description: 5v / 100ma Ldo W/ Reset, Delay Reset And Early Warning
• Manufacturer: ON Semiconductor

regulator. Several outstanding features and auxiliary
functions are implemented to meet the requirements of
supplying
applications. It is also suitable in other applications where
the included functions are required. The modular approach
of this device allows the use of other features and functions
independently when required.
Voltage Regulator
PNP transistor as a regulating element. With this structure,
very low dropout voltage at currents up to 100 mA is
obtained. The dropout operation of the standby regulator is
maintained down to 3.0 V input supply voltage. The output
voltage is regulated up to a transient input supply voltage of
35 V.
function of the input supply voltage is shown in Figure 14.
is less than 200 mA.
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 15.
Short Circuit Protection:
of short circuit, the output current is foldback current limited
as described in Figure 13.
The L4949 is a monolithic integrated low dropout voltage
The voltage regulator uses an isolated collector vertical
A typical curve showing the standby output voltage as a
The current consumption of the device (quiescent current)
To reduce the quiescent current peak in the undervoltage
The maximum output current is internally limited. In case
5.0
10
0
20
Figure 13. Foldback Characteristic of V
microprocessor
100
I
out
(mA)
systems
in
OPERATING DESCRIPTION
automotive
out
L4949, NCV4949
http://onsemi.com
200
7
Preregulator
the internal supply voltage to 6.0 V. This internal voltage is
present at Pin 3 (V
output because the output capability is very small (≤ 100
mA).
supply voltages less than 8.0 V. In this case a capacitor (100
nF - 1.0 mF) must be connected between Pin 3 and GND. If
this feature is not used Pin 3 must be left open.
5.0 V
V
out
To improve transient immunity a preregulator stabilizes
This output may be used to improve transient behavior for
Figure 15. Quiescent Current versus Supply Voltage
3.0
2.5
2.0
1.5
1.0
0.5
0 V
0
Figure 14. Output Voltage versus Supply Voltage
0
2.0 V
T
J
= 25°C
5.0
Z
). This voltage should not be used as an
5.0 V
V
10
CC
, SUPPLY VOLTAGE (V)
15
R
V
R
L
CC
V
L
= 100 W
out
= 5.0 k
20
25
35 V
30