TC1017 datasheet(12/22 Pages) MICROCHIP

12 / 22 page

TC1017

DS21813D-page 12

5.0

THERMAL CONSIDERATIONS

5.1

Thermal Shutdown

Integrated thermal protection circuitry shuts the

regulator off when the die temperature exceeds

approximately 160°C. The regulator remains off until

the die temperature drops to approximately 150°C.

5.2

Power Dissipation: SC-70

The TC1017 is available in the SC-70 package. The

thermal

resistance

for

the

SC-70

package

approximately 450°C/W when the copper area used in

the PCB layout is similar to the JEDEC J51-7 high ther-

mal conductivity standard or semi-G42-88 standard.

For applications with a larger or thicker copper area,

the thermal resistance can be lowered. See AN792, “A

Method to Determine How Much Power a SOT-23 Can

Dissipate in an Application”, DS00792, for a method to

determine the thermal resistance for a particular appli-

cation.

The TC1017 power dissipation capability is dependant

upon several variables: input voltage, output voltage,

load current, ambient temperature and maximum

junction temperature. The absolute maximum steady-

state junction temperature is rated at +125°C. The

power dissipation within the device is equal to:

EQUATION 5-1:

The VIN x IGND term is typically very small when

compared to the (VIN–VOUT) x ILOAD term, simplifying

the power dissipation within the LDO to be:

EQUATION 5-2:

determine

the

maximum

power

dissipation

capability, the following equation is used:

EQUATION 5-3:

Given the following example:

Find:

Internal power dissipation:

Maximum allowable ambient temperature:

Maximum

allowable

power

dissipation

desired ambient:

In this example, the TC1017 dissipates approximately

158.5 mW and the junction temperature is raised 71°C

over the ambient. The absolute maximum power

dissipation is 155 mW when given a maximum ambient

temperature of 55°C.

Input voltage, output voltage or load current limits can

also be determined by substituting known values in the

power dissipation equations.

Figure 5-1 and Figure 5-2 depict typical maximum

power dissipation versus ambient temperature, as well

as typical maximum current versus ambient tempera-

ture, with a 1V input voltage to output voltage

differential, respectively.

FIGURE 5-1:

Power Dissipation vs.

Ambient Temperature (SC-70 package).

OUT

–

() I

LOAD

GN D

OUT

–

() I

LOAD

DMAX

J_MAX

A_MAX

–

()

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

Where:

TJ_MAX = the maximum junction

temperature allowed

TA_MAX = the maximum ambient

temperature

θJA

= the thermal resistance from

junction to air

VIN = 3.0V to 4.1V

VOUT = 2.85V ±2.5%

ILOAD = 120 mA (output current)

TA = 55°C (max. desired ambient)

DMAX

IN_MAX

OUT_MIN

–

() I

LOAD

4.1V

2.85

0.975

()

–

() 120mA

158.5mW

A_MAX

J_MAX

–

DM AX

125

°C 158.5mW 450°C/W

–

()

°C

125

°C71°C

–

()

J_MAX

–

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

155mW

125

°C55°C

–

450

°C/W

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

100

150

200

250

300

350

400

-40

-15

110

Ambient Temperature (°C)

TC1017 数据表(PDF) 12 Page - Microchip Technology

TC1017 数据表(HTML) 12 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

数据表下载

链接网址

TC1017 数据表(PDF) 12 Page - Microchip Technology

TC1017 数据表(HTML) 12 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

数据表 下载

链接网址

数据表下载