NCP698 데이터 시트보기 (PDF) - ON Semiconductor
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NCP698 Datasheet PDF : 9 Pages
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NCP698
APPLICATIONS INFORMATION
A typical application circuit for the NCP698 is shown in
Figure 1.
Input Decoupling (C1)
A 1.0 mF capacitor either ceramic or tantalum is
recommended and should be connected close to the NCP698
package. Higher values and lower ESR will improve the
overall line transient response.
TDK capacitor: C2012X5R1C105K, or C1608X5R1A105K
Output Decoupling (C2)
The NCP698 is a very stable regulator and does not
require any specific Equivalent Series Resistance (ESR) or
a minimum output current. Capacitors exhibiting ESRs
ranging from a few mW up to 10 W can thus safely be used.
The minimum decoupling value is 0.1 mF and can be
augmented to fulfill stringent load transient requirements.
The regulator accepts ceramic chip capacitors as well as
tantalum devices. Larger values improve noise rejection and
load regulation transient response.
TDK capacitor: C2012X5R1C105K, C1608X5R1A105K,
or C3216X7R1C105K
Enable Operation
The enable pin will turn on the regulator when pulled high
and turn off the regulator when pulled low. These limits of
threshold are covered in the electrical specification section
of this data sheet. If the enable is not used, then the pin
should be connected to Vin.
Hints
Please be sure the Vin and GND lines are sufficiently
wide. When the impedance of these lines is high, there is a
chance to pick up noise or cause the regulator to
malfunction.
Place external components, especially the output
capacitor, as close as possible to the circuit, and make leads
as short as possible.
Thermal
As power across the NCP698 increases, 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 effect the rate of temperature rise for the part.
This is stating that when the devices have good thermal
conductivity through the PCB, the junction temperature will
be relatively low with high power dissipation applications.
The maximum dissipation the package can handle is
given by:
PD
+
TJ(max) *TA
RqJA
If junction temperature is not allowed above the
maximum 125°C, then the NCP698 can dissipate up to
250 mW @ 25°C.
The power dissipated by the NCP698 can be calculated
from the following equation:
Ptot + [Vin * IgndĂ(Iout)] ) [Vin * Vout] * Iout
or
VinMAX
+
Ptot ) Vout * Iout
Ignd ) Iout
If an 80 mA output current is needed then the ground
current from the data sheet is 2.5 mA. For an NCP698
(3.0 V), the maximum input voltage will then be 6.0 V.
350
330
310
290
270
250
230
210
190
170
150
0
No pin connected to Cu Plane
Pin 2 connected to Cu Plane
100 200 300 400 500 600 700
PCB COPPER AREA (mm2)
Figure 12. RqJA vs. Pad Copper Area
(1 oz Cu thickness)
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