NCP4683
www.onsemi.com
17
TYPICAL CHARACTERISTICS
Figure 58. Shutdown, 3.3 V Version D,
V
IN
= 4.3 V
−1.0
0
1.0
2.0
3.0
4.0
0 100 200 300 400 500 600 700 800 900 1000
0
2
4
6
V
OUT
(V)
t (ms)
V
CE
(V)
I
OUT
= 300 mA
I
OUT
= 1 mA
I
OUT
= 30 mA
Chip Enable
APPLICATION INFORMATION
A typical application circuit for NCP4683 series is shown
in Figure 59.
VIN VOUT
CE
GND
C1 C2
VIN VOUT
NCP4683x
1m
1m
Figure 59. Typical Application Schematic
Input Decoupling Capacitor (C1)
A 1 mF ceramic input decoupling capacitor should be
connected as close as possible to the input and ground pin of
the NCP4683. Higher values and lower ESR improves line
transient response.
Output Decoupling Capacitor (C2)
A 1 mF ceramic output decoupling capacitor is enough to
achieve stable operation of the IC. If a tantalum capacitor is
used, and its ESR is high, loop oscillation may result. The
capacitors should be connected as close as possible to the
output and ground pins. Larger values and lower ESR
improves dynamic parameters.
Enable Operation
The enable pin CE may be used for turning the regulator
on and off. The IC is switched on when a high level voltage
is applied to the CE pin. The enable pin has an internal pull
down current source. If the enable function is not needed
connect CE pin to VIN.
Current Limit
This regulator includes fold−back type current limit
circuit. This type of protection doesn’t limit current up to
current capability in normal operation, but when over
current occurs, output voltage and current decrease until
over current condition ends. Typical characteristics of this
protection type can be observed in the Output Voltage vs.
Output Current graphs shown in the typical characteristics
chapter of this datasheet.
Output Discharger
The D version includes a transistor between VOUT and
GND that is used for faster discharging of the output
capacitor. This function is activated when the IC goes into
disable mode.
Thermal
As power across the IC increase, it might become
necessary to provide some thermal relief. The maximum
power dissipation supported by the device is dependent
upon board design and layout. Mounting pad configuration
on the PCB, the board material, and also the ambient
temperature affect the rate of temperature increase for the
part. When the device has good thermal conductivity
through the PCB the junction temperature will be relatively
low in high power dissipation applications.
PCB layout
Make the VIN and GND line as large as practical. If their
impedance is high, noise pickup or unstable operation may
result. Connect capacitors C1 and C2 as close as possible to
the IC, and make wiring as short as possible.
