LTC3255 datasheet(11/14 Pages) AD

11 / 14 page

LTC3290

Rev. 0

For more information www.analog.com

APPLICATIONS INFORMATION

Figure 5. Recommended Layout

Figure 6. Maximum Power Dissipation vs Ambient Temperature

Derating Power at High Temperatures

To prevent an overtemperature condition in high power

applications, Figure 6 should be used to determine the

maximumcombinationofambienttemperatureandpower

dissipation.

The power dissipated in the LTC3290 should always fall

under the recommended operation line shown for a given

ambient temperature.

Power dissipated in the LTC3290:

PD = (VIN + VAUX – VOUT) • IOUT

where IOUT denotes the output load current.

The derating curve in Figure 6 assumes a maximum ther-

mal resistance, θJA, of 45°C/W for the package. This can

be achieved with a four layer PCB that includes 2oz Cu

traces and six vias from the exposed pad of the LTC3290

to the ground plane.

It is recommended that the LTC3290 be operated in the

region corresponding to TJ ≤ 150°C for continuous op-

eration as shown in Figure 6. Operation beyond 150°C

should be avoided as it may degrade part performance

andlifetime.Athightemperatures,typicallyaround175°C,

the part goes into thermal shutdown and all outputs are

disabled. When the part cools back down to a low enough

temperature, typically around 165°C, the outputs are re-

enabled and the part resumes normal operation.

AMBIENT TEMPERATURE (°C)

–50

6.0

5.0

3.0

1.0

4.0

2.0

150

100

3290 F06

175

125

–25

θJA = 45°C/W

RECOMMENDED

OPERATION

THERMAL

SHUTDOWN

TJ = 175°C

TJ = 150°C

VAUX

VOUT

CAUX

GND

BOOST LAYOUT

CIN

VIN

COUT

CBYP

3290 F05

CFLY

VAUX

VOUT

CAUX

GND

VIN TRACKING LAYOUT

CIN

VIN

CBYP

CFLY

COUT

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