MCP1802 Microchip Technology, MCP1802 Datasheet - Page 14

• Manufacturer Part Number: MCP1802
• Description: Low Quiescent Current LDO
• Manufacturer: Microchip Technology

MCP1802
6.0
6.1
The MCP1802 is most commonly used as a voltage
regulator. Its low quiescent current and low dropout
voltage make it ideal for many battery-powered
applications.
FIGURE 6-1:
6.1.1
6.2
6.2.1
The internal power dissipation of the MCP1802 is a
function of input voltage, output voltage and output
current. The power dissipation, as a result of the
quiescent current draw, is so low, it is insignificant
(25.0 µA x V
calculate the internal power dissipation of the LDO.
EQUATION 6-1:
The maximum continuous operating temperature
specified for the MCP1802 is +85
internal junction temperature of the MCP1802, the total
internal power dissipation is multiplied by the thermal
resistance from junction to ambient (Rθ
resistance from junction to ambient for the SOT-23-5
package is estimated at 256
DS22053A-page 14
I
50 mA
Where:
OUT
V
P
V
1.8V
V
OUT(MIN)
Input Voltage Range =
LDO
OUT
IN(MAX)
P
APPLICATION CIRCUITS &
ISSUES
Typical Application
Power Calculations
LDO
=
Package Type =
V
APPLICATION INPUT CONDITIONS
POWER DISSIPATION
IN
(
IN
V
V
). The following equation can be used to
OUT
IN MAX )
C
1 µF Ceramic
maximum =
=
=
=
OUT
(
Typical Application Circuit.
V
typical =
NC
OUT
LDO Pass device internal power
dissipation
Maximum input voltage
LDO minimum output voltage
I
MCP1802
OUT
)
–
V
=
OUT MIN
°
C/W.
SHDN
GND
V
(
SOT-23-5
2.4V to 5.0V
5.0V
1.8V
50 mA maximum
IN
°
)
C
) I
.
×
To estimate the
JA
OUT MAX )
). The thermal
V
2.4V to 5.0V
C
1 µF
Ceramic
IN
IN
(
)
EQUATION 6-2:
The maximum power dissipation capability for a
package can be calculated given the junction-to-
ambient thermal resistance and the maximum ambient
temperature for the application. The following equation
can be used to determine the package maximum
internal power dissipation.
EQUATION 6-3:
EQUATION 6-4:
EQUATION 6-5:
Where:
Where:
Where:
Where:
P
T
T
T
T
T
P
P
T
D(MAX)
A(MAX)
J(RISE)
J(RISE)
J(MAX)
J(MAX)
TOTAL
TOTAL
AMAX
Rθ
Rθ
Rθ
T
P
T
T
JA
JA
JA
J MAX
D MAX
A
J
(
(
T
J RISE
=
=
=
=
=
=
=
=
=
=
=
=
=
=
(
)
)
T
=
=
J
Maximum continuous junction
temperature
Total device power dissipation
Thermal resistance from
junction to ambient
Maximum ambient temperature
Maximum device power
dissipation
Maximum continuous junction
temperature
Maximum ambient temperature
Thermal resistance from
junction to ambient
Rise in device junction
temperature over the ambient
temperature
Maximum device power
dissipation
Thermal resistance from
junction to ambient
Junction Temperature
Rise in device junction
temperature over the ambient
temperature
Ambient temperature
P
)
=
(
---------------------------------------------------
TOTAL
T
=
T
© 2007 Microchip Technology Inc.
J MAX
(
P
J RISE
(
D MAX
(
×
Rθ
)
Rθ
–
)
JA
+
T
)
JA
A MAX
×
T
(
A
Rθ
+
T
JA
AMAX
)
)