cs5205a-1 ON Semiconductor, cs5205a-1 Datasheet - Page 5

• Manufacturer Part Number: cs5205a-1
• Description: 5.0 A Adjustable Linear Regulator
• Manufacturer: ON Semiconductor

Output Voltage Sensing
possible to provide true remote load sensing. Load
regulation is limited by the resistance of the conductors
connecting the regulator to the load.
to the output pin of the regulator as shown in Figure 9. If R1
is connected to the load, R
and the effective resistance between the regulator and the
load becomes
where R
V
V
IN
Figure 9. Grounding Scheme for Adjustable Output
Since the CS5205A−1 is a three terminal regulator, it is not
Best load regulation occurs when R1 is connected directly
IN
Figure 8. Protection Diode Scheme for Adjustable
C
1
C
= conductor parasitic resistance.
V
Regulator to Minimize Parasitics
IN
CS5205A−1
V
IN
Adj
IN4002 (optional)
CS5205A−1
Output Regulator
R C
V
Adj
OUT
C
C
Adj
is multiplied by the divider ratio
R1 ) R2
V
OUT
R1
R
R
1
2
R
C
R
Conductor Parasitic
R
1
2
Resistance
C
2
V
http://onsemi.com
R
OUT
LOAD
5
Calculating Power Dissipation and Heat Sink
Requirements
and safe operating area circuitry to protect the device. High
power regulators such as these usually operate at high junction
temperatures so it is important to calculate the power
dissipation and junction temperatures accurately to ensure that
an adequate heat sink is used.
electrical isolation may be required for some applications.
Thermal compound should always be used with high current
regulators such as these.
following four factors:
1. Maximum Ambient Temperature T
2. Power dissipation P
3. Maximum junction temperature T
4. Thermal resistance junction to ambient R
dissipation are determined by the design while the
maximum junction temperature and the thermal resistance
depend on the manufacturer and the package type.
P D(max) + { V IN(max) * V OUT(min) } I OUT(max) ) V IN(max) I Q
where:
V
V
I
I
package to improve the flow of heat away from the IC and
into the surrounding air.
outside environment has a thermal resistance. Like series
electrical resistances, these resistances are summed to
determine R
junction and the surrounding air.
1. Thermal Resistance of the junction to case, R
2. Thermal Resistance of the case to Heat Sink, R
3. Thermal Resistance of the Heat Sink to the ambient
OUT(max)
Q
IN(max)
OUT(min)
The CS5205A−1 linear regulator includes thermal shutdown
The case is connected to V
The thermal characteristics of an IC depend on the
These four are related by the equation
The maximum ambient temperature and the power
The maximum power dissipation for a regulator is:
A heat sink effectively increases the surface area of the
Each material in the heat flow path between the IC and the
These are connected by the equation:
is the maximum quiescent current at I
(°C/W)
(°C/W)
air, R
is the maximum input voltage,
ΘSA
is the maximum output current, for the application
is the minimum output voltage,
R QJA + R QJC ) R QCS ) R QSA
ΘJA
(°C/W)
, the total thermal resistance between the
T J + T A ) P D
D
(Watts)
OUT
R QJA
on the CS5205A−1,
J
A
(°C)
OUT(max)
(°C)
ΘJA
.
ΘJC
(°C/W)
ΘCS
(1)
(2)
(3)