MCP1725 Ver la hoja de datos (PDF) - Microchip Technology

Número de pieza

componentes Descripción

Fabricante

MCP1725

500 mA, Low Voltage, Low Quiescent Current LDO Regulator

Microchip Technology 

MCP1725

5.0 APPLICATION CIRCUITS/

ISSUES

5.1 Typical Application

The MCP1725 is used for applications that require high

LDO output current and a power good output.

VIN = 3.3V

C1

10 µF

On

Off

MCP1725-2.5

1 VIN

VOUT 8

2 VIN Sense 7

3 SHDN CDELAY 6

4 GND PWRGD 5

VOUT = 2.5V @ 0.5A

R1

10kΩ

C2

10 µF

C3

1000 pF

PWRGD

FIGURE 5-1:

Typical Application Circuit.

5.1.1 APPLICATION CONDITIONS

Package Type = 2x3 DFN8

Input Voltage Range = 3.3V ± 5%

VIN maximum = 3.465V

VIN minimum = 3.135V

VDROPOUT (max) = 0.350V

VOUT (typical) = 2.5V

IOUT = 0.5A maximum

PDISS (typical) = 0.4W

Temperature Rise = 30.4°C

5.2 Power Calculations

5.2.1 POWER DISSIPATION

The internal power dissipation within the MCP1725 is a

function of input voltage, output voltage, output current,

and quiescent current. Equation 5-1 can be used to

calculate the internal power dissipation for the LDO.

EQUATION 5-1:

PLDO = (VIN(MAX)) – VOUT(MIN)) × IOUT(MAX))

Where:

PLDO = LDO Pass device internal

power dissipation

VIN(MAX) = Maximum input voltage

VOUT(MIN) = LDO minimum output voltage

In addition to the LDO pass element power dissipation,

there is power dissipation within the MCP1725 as a

result of quiescent or ground current. The power

dissipation as a result of the ground current can be

calculated using the following equation:

EQUATION 5-2:

Where:

PI(GND) = VIN(MAX) × IVIN

PI(GND = Power dissipation due to the

quiescent current of the LDO

VIN(MAX) = Maximum input voltage

IVIN = Current flowing in the VIN pin

with no LDO output current

(LDO quiescent current)

The total power dissipated within the MCP1725 is the

sum of the power dissipated in the LDO pass device

and the P(IGND) term. Because of the CMOS

construction, the typical IGND for the MCP1725 is

120 µA. Operating at 3.465V results in a power dissipa-

tion of 0.42 milli-Watts. For most applications, this is

small compared to the LDO pass device power

dissipation and can be neglected.

The maximum continuous operating junction

temperature specified for the MCP1725 is +125°C. To

estimate the internal junction temperature of the

MCP1725, the total internal power dissipation is

multiplied by the thermal resistance from junction to

ambient (RθJA) of the device. The thermal resistance

from junction to ambient for the 2x3 DFN package is

estimated at 76° C/W.

EQUATION 5-3:

TJ(MAX) = PTOTAL × RθJA + TAMAX

TJ(MAX) = Maximum continuous junction

temperature

PTOTAL = Total device power dissipation

RθJA = Thermal resistance from junction to

ambient

TAMAX = Maximum ambient temperature

DS22026B-page 20

© 2007 Microchip Technology Inc.

Share Link: