PAM2808

Document number: DS36402 Rev. 2 - 2

5 of 8

www.diodes.com

September 2015

© Diodes Incorporated

PAM2808

Application Information

PWM Dimming

switched on and off causing the LED current to turn on and off. The recommended PWM frequency is 200Hz (see Figure 5 for details).

External Capacitor Requirements

additional 1

0μF or larger, low ESR capacitor is recommended at the output. A higher-value, low ESR output capacitor may be necessary if large,

fast-rise-time load transients are anticipated and the device is located several inches from the power source, especially if the minimum input

voltage of 2.5V is used.

Regulator Protection

The PAM2808 features internal current limiting, thermal protection and short circuit protection. During normal operation, the PAM2808 limits

output current to about 2.5A. When current limiting engages, the output voltage scales back linearly until the over current condition ends. While

current limiting is designed to prevent gross device failure, care should be taken not to exceed the power dissipation ratings of the package. If the

temperature of the device exceeds +150°C, thermal-protection circuitry will shut down. Once the device has cooled down to approximately +40°C

below the high temperature trip point, regulator operation resumes.

Thermal Information

The amount of heat generates is:



V

V

P

O

O

IN

D

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

purpose of this information is to aid the designer in determining the proper operating environment for a linear regulator that is operating at a

specific power level.





I

x

V

I

x

V

V

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)

Q

(

)

AVG

(

I

)

AVG

(

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)

AVG

(

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)

AVG

(

I

DMAX





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Where:

dissipation. The temperature rise is computed by multiplying the maximum expected power dissipation by the sum of the thermal resistances

how effectively an object dissipates heat. Typically, the larger the device, the more surface area available for power dissipation so that the

objec

t’s thermal resistance will be lower.