CS8481YDP5 ONSEMI [ON Semiconductor], CS8481YDP5 Datasheet - Page 5

• Manufacturer Part Number: CS8481YDP5
• Description: 3.3 V/250 mA, 5.0 V/100 mA Micropower Low Dropout Regulator with ENABLE
• Manufacturer: ONSEMI [ON Semiconductor]

ENABLE
is high, V
Calculating Power Dissipation in a
Dual Output Linear Regulator
regulator (Figure 3) is
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.
P D(max) + V IN(max) * V OUT1(min) I OUT1(max) )
qJA
The ENABLE function controls V
The maximum power dissipation for a dual output
V
V
V
I
application,
I
application, and
I
I
Once the value of P
The value of R
In some cases, none of the packages will be sufficient to
OUT1(max)
OUT2(max)
Q
OUT1(max)
IN(max)
OUT1(min)
OUT2(min)
’s less than the calculated value in equation 2 will keep
is the quiescent current the regulator consumes at both
** C
OUT1
* C
V IN(max) * V OUT2(min) I OUT2(max) ) V IN(max) IQ
is the maximum input voltage,
1
2
and I
is the minimum output voltage from V
is the minimum output voltage from V
required if regulator is located far from power supply filter.
and C
is the maximum output current, for the
is the maximum output current, for the
is on. When ENABLE is low, V
Load
R QJA +
qJA
OUT2(max)
V
3
BATT
required for stability. Capacitor must operate at minimum temperature expected during system operations.
qJA
can be compared with those in the
D(max)
can be calculated:
ESR < 8 W
150°C * T A
.
0.1 mF
22 mF
is known, the maximum
P D
OUT1
. When ENABLE
C
C
Figure 4. Test and Application Circuit
1
3
*
**
OUT1
V
V
IN
OUT1
http://onsemi.com
OUT1
OUT2
is off.
CS8481
GND
(1)
(2)
CS8481
,
,
ENABLE
5
V
OUT2
Heat Sinks
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
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
V
IN
qJC
qCS
qSA
qJC
, it too is a function of package type. R
Figure 3. Dual Output Regulator With Key
C
= 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.
2
I
IN
**
Performance Parameters Labeled.
R QJA + R QJC ) R QCS ) R QSA
22 mF
ESR < 8 W
REGULATOR
Control
Features
SMART
qJA:
V
I/O
CC
I
Q
mP
GND
I
I
OUT1
OUT2
qCS
and R
V
V
OUT2
qSA
OUT1
are
(3)