NCV8769 Datasheet, PDF (13/14 Pages) ON Semiconductor – Ultra Low Iq 150 mA LDO Regulator with Reset and Early Warning

NCV8769
V _out
VSI
V _SI,Low
VRO
VSO
T _WARNING
Figure 23. SO Warning Timing Diagram
Sense
Input
VSI,High
VSI,Low
Sense
Output
High
tPSOLH
t
tPSOHL
Low
t
Figure 24. Sense Input to Sense Output Timing
Diagram
Thermal Considerations
As power in the NCV8769 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 the ambient temperature
affect the rate of junction temperature rise for the part. When
the NCV8769 has good thermal conductivity through the
PCB, the junction temperature will be relatively low with
high power applications. The maximum dissipation the
NCV8769 can handle is given by:
ƪ ƫ T_J(MAX) * T_A
P_D(MAX) +
R_qJA
(eq. 3)
Since T_J is not recommended to exceed 150°C, then the
NCV8769 soldered on 645 mm², 1 oz copper area, FR4 can
dissipate up to 1.33 W when the ambient temperature (T_A)
is 25°C. See Figure 25 for R_thJA versus PCB area. The power
dissipated by the NCV8769 can be calculated from the
following equations:
P_D [ V_in^ǒI_q@I_out^Ǔ ) I_out^ǒV_in * V_out^Ǔ
(eq. 4)
or
P_D(MAX) ) ^ǒV_out
V_in(MAX) [
I_out ) I_q
I_out^Ǔ
(eq. 5)
120
110
PCB 1 oz Cu
100
90
PCB 2 oz Cu
80
70
60
0 100 200 300 400 500 600 700
COPPER HEAT SPREADER AREA (mm²)
Figure 25. Thermal Resistance vs. PCB Copper Area
Hints
V_in and GND printed circuit board traces should be as
wide as possible. When the impedance of these traces 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 NCV8769 and
make traces as short as possible.
ORDERING INFORMATION
Device
Output
Voltage
Reset Delay Time
DT = GND/V_out
Reset
Threshold
(Typ)
Marking
Package
Shipping^†
NCV876950D250R2G
5.0 V
16/32 ms
93 %
V87695050G SO−14 2500 / Tape & Reel
(Pb−Free)
†For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging
Specifications Brochure, BRD8011/D
http://onsemi.com
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