JMG
Member level 3
Hi Board,
Was wondering if someone could help me with my calculations? Specifically inductor value.
Datasheet: **broken link removed**
Equation is on page 15.
Numbers:
Vinmin = 22
Vled = 26
Iled = 11
Vd = 0.7
Vfet = 0.2
ΔIL = 0.25
fSW = 250,000
Working out for the buck-boost mode I get:
DMax = 0.5505
ILavg = 24.4716
ILp = 24.5966
L = 192uH
If this is correct I need a 192uH 30A inductor!! 8O
Now my alternative is to put the LED's in series and have 105V @ 2.2A, but I worry about the legalities of selling that in the US. Is there a low voltage directive such as there is in the UK and Europe?
Added after 4 hours 50 minutes:
Oops, there needs to be more than 250mA ripple in the inductor current. 1.60A Pk - Pk and upping fSW to 900kHz brings the inductor requirements down to 8.2uH.
Was wondering if someone could help me with my calculations? Specifically inductor value.
Datasheet: **broken link removed**
Equation is on page 15.
Numbers:
Vinmin = 22
Vled = 26
Iled = 11
Vd = 0.7
Vfet = 0.2
ΔIL = 0.25
fSW = 250,000
Working out for the buck-boost mode I get:
DMax = 0.5505
ILavg = 24.4716
ILp = 24.5966
L = 192uH
If this is correct I need a 192uH 30A inductor!! 8O
Now my alternative is to put the LED's in series and have 105V @ 2.2A, but I worry about the legalities of selling that in the US. Is there a low voltage directive such as there is in the UK and Europe?
Added after 4 hours 50 minutes:
Oops, there needs to be more than 250mA ripple in the inductor current. 1.60A Pk - Pk and upping fSW to 900kHz brings the inductor requirements down to 8.2uH.