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Oct 23-06

SP7615 Four Channel Constant Current LED Driver

© Copyright 2006 Sipex Corporation

THEORY OF OPERATION

The voltage applied to the cathode of each

LED determines the overall efficiency of the

SP7615 circuit. The SP7615 is designed to

be able to sink 125mA at each of its four

outputs; LED1 - 4. The SP7615 is also

designed to be able to handle up to 16V on

these pins. This voltage handling capability

assumes the total power can be dissipated

by the SP7615. The power dissipation inside

the SP7615 will de directly related to the

voltage and current applied to these pins.

For example, the typical operating cathode

voltage is 500mV. At maximum current the

EN

GND

C1

1n

R1

R2

SP7615

®

EN

GND

LED1

LED2

LED3

LED4

SP7615

®

EN

GND

LED1

LED2

LED3

LED4

power dissipated by one LED driver output

is 125mA * 500mV = 62.5mW. The charts in

the following pages show the power

dissipation of the SP7615 under various

conditions. The power dissipation should

be kept below 1.3W for safe operation and

long term reliability at room temperature

above operating conditions are recommended,

the part cannot be damaged due to internal

temperature control as described above in

the thermal shutdown section.

CATHODE VOLTAGE, SUPPLY VOLTAGE

AND POWER DISSIPATION

Current sharing capabilities allow two SP7615s to run in

parallel for twice as much current through the LEDs.