MIC3230_11 Datasheet, PDF (12/19 Pages) Micrel Semiconductor – Constant Current Boost Controller for Driving High Power LEDs

Micrel, Inc.
MIC3230/1/2
Figure 6. IS Pin and V_RCS (Ch1 = Switch Node, Ch2 = IS Pin, Ref1 = V_CS)
Design Procedure for a LED Driver
Symbol
V_IN
I_IN
Parameter
Input
Input Voltage
Input current
Min
Nom
Max
8
12
14
2
Output
LEDs
Number of LEDs
5
6
7
V_F
Forward voltage of LED
3.2
3.5
4.0
V_OUT
Output voltage
16
21
28
I_LED
LED current
0.33
0.35
0.37
I_PP
Required I Ripple
40
PWMD PWM Dimming
0
100
OVP
Output over voltage protection
30
F_SW
eff
V_DIODE
System
Switching frequency
Efficiency
Forward drop of schottky diode
500kHz
80
0.6
Table 2. Design Example Parameters
Units
V
A
V
V
A
mA
%
V
%
V
March 2011
12
M9999-030311-D