CS8129 ON Semiconductor, CS8129 Datasheet - Page 7

• Manufacturer Part Number: CS8129
• Description: Low Dropout Linear Regulator
• Manufacturer: ON Semiconductor

various loads at several frequencies to simulate its real
working environment. Vary the ESR to reduce ringing.
operating temperature. Vary the load current as instructed in
step 5 to test for any oscillations.
ESR is found, a safety factor should be added to allow for the
tolerance of the capacitor and any variations in regulator
performance. Most good quality aluminum electrolytic
capacitors have a tolerance of ± 20% so the minimum value
found should be increased by at least 50% to allow for this
tolerance plus the variation which will occur at low
temperatures. The ESR of the capacitor should be less than
50% of the maximum allowable ESR found in step 3 above.
regulator (Figure 14) is:
P D(max) + V IN(max) * V OUT(min) I OUT(max) ) V IN(max) I Q
where:
permissible value of R
package section of the data sheet. Those packages with
R
the die temperature below 150°C.
dissipate the heat generated by the IC, and an external
heatsink will be required.
qJA
Step 6: Test the load transient response by switching in
Step 7: Raise the temperature to the highest specified
Once the minimum capacitor value with the maximum
CALCULATING POWER DISSIPATION IN A SINGLE
The maximum power dissipation for a single output
V
V
I
I
Once the value of P
The value of R
In some cases, none of the packages will be sufficient to
OUT(max)
Q
IN(max)
OUT(min)
application, and
I
’s less than the calculated value in equation 2 will keep
is the quiescent current the regulator consumes at
OUT(max)
is the maximum input voltage,
is the maximum output current for the
OUTPUT LINEAR REGULATOR
is the minimum output voltage,
.
qJA
R qJA +
can then be compared with those in the
qJA
D(max)
can be calculated:
150°C * T A
P D
is known, the maximum
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(1)
(2)
CS8129
7
package to improve the flow of heat away from the IC and
into the surrounding air.
outside environment will have a thermal resistance. Like
series electrical resistances, these resistances are summed to
determine the value of R
where:
R
functions of the package type, heatsink and the interface
between them. These values appear in heat sink data sheets
of heat sink manufacturers.
qJA
V
A heat sink effectively increases the surface area of the
Each material in the heat flow path between the IC and the
R
R
R
R
IN
qJC
qCS
qSA
qJC
, it too is a function of package type. R
Figure 14. Single Output Regulator With Key
= the junction−to−case thermal resistance,
appears in the package section of the data sheet. Like
= the case−to−heatsink thermal resistance, and
= the heatsink−to−ambient thermal resistance.
Performance Parameters Labeled
I
IN
R qJA + R qJC ) R qCS ) R qSA
REGULATOR
HEAT SINKS
qJA
SMART
Control
Features
.
I
Q
®
I
qCS
OUT
and R
qSA
V
OUT
(3)
are