STLED25JR STMicroelectronics, STLED25JR Datasheet - Page 20

• Manufacturer Part Number: STLED25JR
• Description: LED Lighting Drivers 5-Ch LED Step Up WH LED 2.3V to 5.5V
• Manufacturer: STMicroelectronics

Specifications of STLED25JR

• Product Category: LED Lighting Drivers
• Rohs: yes

Application information
7
7.1
7.1.1
Table 7.
7.1.2
20/30
Manufacturer
Samsung
Murata
Application information
External passive components
Inductor selection
The inductor is the key passive component for switching converters.
For the STLED25, an inductance of 4.7 µH is recommended. It is very important to select
the right inductor according to the maximum current the inductor can handle to avoid
saturation. The peak current for the step-up can be calculated with the following formula:
Equation 2
where:
V
maximum among VD1-D5
I
V
fs: switching frequency. Use the minimum value of 2.25 MHz for the worst case
η: efficiency of step-up converter. It is 0.87 at 75 mA load
List of recommended inductors
Input and output capacitor selection
It is recommended to use ceramic capacitors with low ESR as input and output capacitors in
order to filter any disturbance present in the input line and to maintain stable operation of the
step-up converter. A minimum real capacitance value of 1 µF must be guaranteed for C
and 4.2 µF C
OUT
OUT
IN
: input voltage of STLED25
: total output current
: step-up output voltage. The boost control loop keeps it 135 mV higher than the
CIG21K4R7SCE
LQM21PN4R7
OUT
Part number
I
PEAK
in all conditions.
−
BOOST
Doc ID 022323 Rev 3
=
V
η
OUT
×
Inductance
VIN
×
[µH]
4.7
4.7
I
MIN
OUT
+
VIN
Saturation current [A]
MIN
2
×
×
V
(
OUT
V
0.6
0.6
OUT
×
fs
−
VIN
×
L
MIN
)
Size [mm]
0805
0805
STLED25
IN