LM3401

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SNVS516C – AUGUST 2007 – REVISED MAY 2013

This is the estimated amount of LED current variation over the input voltage range. If the minimum input voltage

was below 17V, the LED current variation would be calculated using the 100% duty cycle equation.

Table 1. Design Example Summary

Parameter

Value

Result

Comment

R1

290 m

Ω

690 mA DC

1%

R2

5.6 k

Ω

±22.4 mV hysteresis

L1

33 µH, >804 mA

-

1MHz typical

219 kHz min

-

227 mA p-p

worst case

-

804 mA

worst case

PFET

40V, 1.8A, 130 m

Ω

R3

46 k

Ω

0.95A minimum peak current limit

adjustable

C1

2.2 µF, 50V ceramic

>345 mA rms

D1

40V, 1A

Schottky

Accuracy

±6.1%

±42 mA max variation

part-to-part

Regulation

1.6%

11 mA variation

vs VIN

Ta_max

108°C

worst case

C2

1.0 µF, 50V

LED ripple reduction

optional

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