MCP1804T-2502ISLASHMB datasheet(23/38 Pages) MICROCHIP

23 / 38 page

DS22200A-page 23

MCP1804

6.0

APPLICATION CIRCUITS AND

ISSUES

6.1

Typical Application

The MCP1804 is most commonly used as a voltage

regulator. It’s low quiescent current and wide input volt-

age make it ideal for Li-Ion and 12V battery-powered

applications.

FIGURE 6-1:

Typical Application Circuit.

6.1.1

APPLICATION INPUT CONDITIONS

6.2

Power Calculations

6.2.1

POWER DISSIPATION

The internal power dissipation of the MCP1804 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

(50.0 µA x VIN). The following equation can be used to

calculate the internal power dissipation of the LDO.

EQUATION 6-1:

The maximum continuous operating temperature

specified for the MCP1804 is +85°C. To estimate the

internal junction temperature of the MCP1804, the total

internal power dissipation is multiplied by the thermal

resistance from junction to ambient (R

JA). The thermal

resistance from junction to ambient for the SOT-25 pin

package is estimated at 256°C/W.

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:

Package Type

= SOT25

Input Voltage Range

= 3.8V to 4.2V

VIN maximum

= 4.6V

VOUT typical

= 1.8V

IOUT

=50 mA maximum

GND

VOUT

VIN

CIN

1µF

COUT

1 µF Ceramic

VOUT

VIN

4.2V

1.8V

IOUT

50 mA

Ceramic

SHDN

LDO

IN MAX

)

()

OUT MIN

()

–

() I

OUT MAX

)

()

Where:

PLDO = LDO Pass device internal power

dissipation

VIN(MAX) = Maximum input voltage

VOUT(MIN) = LDO minimum output voltage

JMAX

()

TOTAL

AMAX

Where:

TJ(MAX)

Maximum continuous junction

temperature.

PTOTAL

Total device power dissipation.

RqJA

Thermal resistance from junction to

ambient.

TAMAX

Maximum ambient temperature.

DMAX

()

JMAX

()

AMAX

()

–

()

---------------------------------------------------

Where:

PD(MAX)

Maximum device power dissipation.

TJ(MAX)

Maximum continuous junction

temperature.

TA(MAX)

Maximum ambient temperature.

RqJA

Thermal resistance from junction to

ambient.

JRISE

()

DMAX

()

Where:

TJ(RISE)

Rise in device junction temperature over

the ambient temperature.

PTOTAL

Maximum device power dissipation.

RqJA

Thermal resistance from junction to

ambient.

JRISE

()

Where:

Junction Temperature.

TJ(RISE)

Rise in device junction temperature over

the ambient temperature.

Ambient temperature.

MCP1804T-2502I/MB Datasheet(PDF) 23 Page - Microchip Technology

MCP1804T-2502I/MB Datasheet(HTML) 23 Page - Microchip Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38

Datasheet Download

Link URL