MIC2299_11 Datasheet, PDF (10/14 Pages) Micrel Semiconductor – 3.5A Minimum, 2MHz High Brightness LED Driver

Micrel, Inc.
Figure 7. BRT Pin PWM Freq = 5kHz
BRT PWM Programming
Should the SS/DIM pin be used for voltage programming
the LED current, note that there will be a small offset due
to mismatches between the FB input and the impedance
driving the SS/DIM pin.
MIC2299
Soft Start Functionality
The soft start time is dependent on both C_SS and the
comp capacitor values. C_COMP is fixed for stable
operation (typically 33nF); therefore, if any increases in
soft start are desired, this should be done using the C_SS
capacitor. The approximate total startup time (in
milliseconds) is given by the larger of: -
T_SS = 1ms + 200k ⋅ C_SS
Or
T_SS = 1ms + C_COMP / 44 ⋅ 10 ^−6
E.g. for C_COMP = 33nF, use values of C_COMP > 4.3nF to
increase startup time from 1.75ms. The soft start
capacitor should be connected from the SS/DIM pin to
ground.
October 2007
10
M9999-101907-B