tb62731fug TOSHIBA Semiconductor CORPORATION, tb62731fug Datasheet - Page 8

• Manufacturer Part Number: tb62731fug
• Description: Step-up Dc-dc Converter For White Led Driver
• Manufacturer: TOSHIBA Semiconductor CORPORATION

inductance of 1.2 times the calculated value.
Substitute the following conditions in formula 2.
Thus, 48.1 ( µ H) is selected when the input voltage is low, 3.0 V.
Note that the calculation does not consider fluctuations in inductance. Toshiba recommend selection of an
The recommended inductance under the above conditions is L ( µ H) = 48.1 ( µ H) × 1.2 > = 57.7 ( µ H).
Supply voltage V
Output-side capacitor C2 = 1 ( µ F) . . . C2 is ignored in the calculation.
Where it is assumed that,
VfLED = 16 (V), Vf schottky = 0.3 (V), R_sens = 1.8 ( Ω ), I
VfLED: LED Vf
Vf schottky: schottky diode Vf
R_sens: setting resistance
I
K: margin
o
: set current
L ( µ H) = ((1.1 × 16 × 0.02) − 3 × 0.02) × (1/275e3) × 2 × (1/(0.21 × 0.21)) = 48.1 ( µ H, V
IN
= 3.0~4.3 (V)
8
o
= 20 (mA), K = 1.1
43.8 ( µ H, V
TB62731FUG
IN
IN
= 3.0 V)
= 4.3 V)
2006-06-14