How to Select Rset for FAN5614 LED Driver

Question

Hello

I would like use several Fairchild FAN5614 LED analog driver ICs and have examined the datasheet however the are no instructions on how to select Rset for the FAN5614 version itself, only the FAN5611/2/3 versions.

The datasheet (Rev 1.0.9) for the FAN5614 states,

"FAN5614 features up to 160mA bias current (up to 80mA for each LED)" in the features section, and

"The FAN5614 drives two high-current LEDs (80mA per output)" in the Description section.

The Absolute Maximum Ratings section also states,

"I1/I2, I3/I4 Steady State Current FAN5614 80 mA"

The FAN5611/12/13 are limited to 40mA/LED, however the FAN5614 is specified for up to 80mA/LED and 160mA total. The datasheet however only specifies how to select Rset for LED currents of up to 40mA (where Iset = 200uA).

I would appreciate any help in determining what the correct Rset would be for an 80mA LED current (Iset = 400uA) from a FAN5614.

Thank you,

D.Hughes

GPG · Accepted Answer

The outputs are doubled up so setting for 40mA = 80mA for the '14

DH · Answer

Very interesting, so "Current Gain" for the FAN5614 in the DC Electrical Characteristics section should read 400 instead of 200 ? Fairchild technical support replied saying that the maximum current/ LED for the FAN5614 was in fact 40mA, ignoring what was stated in the Features, Description, and Absolute Maximum Ratings sections.

Are you positive about this ?

Thank you,

D.Hughes

How to Select Rset for FAN5614 LED Driver

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