STLDC08 STMicroelectronics, STLDC08 Datasheet - Page 18

• Manufacturer Part Number: STLDC08
• Description: Step-up controller for LED supply
• Manufacturer: STMicroelectronics

Application information
8.4
18/29
Equation 6
Where D
Equation 7
The value of the peak current on the inductor is given by the following equation:
Equation 8
The minimum required saturation current of the inductor must be greater than I
be expressed as follows:
Equation 9
The saturation current rating for the inductor should be checked at the maximum duty cycle
and maximum output current.
Inductor peak current limit
The value of the inductor peak current limit can be programmed either by using a sense
resistor or by using the RDSON of the main Power MOSFET.
The following equation gives the relationship between the peak current limit and the value of
the sense resistor:
Equation 10
The sense resistor value can be determined fixing the value of the inductor peak current
limit equal to twice the value of the inductor peak current in steady-state conditions.
MAX
is given by:
Doc ID 18476 Rev 1
Δ
I
L
I
( L
I
=
IN
SAT
40
(
MAX
D
I
%
)
( L
MAX
>
PK
×
)
I
( L
I
=
( L
)
PK
=
R
AVG
V
=
SENSE
1
SENSE
I
)
( L
−
=
)
AVG
V
1
=
OUT
V
−
40
IN
I
OUT
)
D
=
(
+
%
MIN
MAX
+
R
Δ
×
2
SENSE
V
I
)
L
1
D
0
1 .
+
−
I
LED
D
Δ
2
MAX
I
L
L(PK)
STLDC08
and can