stld41pur STMicroelectronics, stld41pur Datasheet - Page 10

• Manufacturer Part Number: stld41pur
• Description: White Led Driver For Mid-size Lcd Display Backlight
• Manufacturer: STMicroelectronics

Selection of external components
7.4
7.5
10/19
For optimal performance of the STLD41 device, is recommended to use an inductor value of
47 µH or higher with low serial resistance and relevant saturation current calculated from the
equation above.
R
R
If using a typical setting of I
must be rated for a power dissipation of 1.3 x 0.122 W = 0.02 W.
PCB layout
Because the STLD41 is a powerful switched device, the PCB must be designed in line with
rules for designing switched supplies. It is recommended to use a two-layer PCB. The power
wirings must be as short as possible and wide. Place all external components close to the
STLD41 device. High-energy switched loops should be as small as possible to reduce EMI.
Most LEDs need cooling, which can be attained utilizing a defined copper area on the PCB.
Use the reference guide for each LED to design the heatsink. Place the R
close as possible to pin 2 and ground of the system. The ground of the system is
represented by the size of the area created by the connections GND-PGDN-GND
GND
PCB must be focused on the minimum area of the application ground; the smaller the
ground area of the DC-DC converter
issues. It is recommended to place the copper plate connected through the vias to the
exposed pad to the bottom layer to create the heatsink of the device.
a. The application ground area is represented by the area which is created by the ground pins of the C
SENSE
SENSE
and ground of the DEVICE and GND connection of the load.
COUT
= V
. When a change of PCB layer is needed, use sufficient vias. During routing, the
value
REF1
/ I
LED
LED
Doc ID 022283 Rev 2
= 120 mA, V
(a)
, the better the stability and there will be fewer noise
REF1
= 160 mV, and R
SENSE
= 1.3 Ω, the resistor
SENSE
resistor as
CIN
STLD41
IN
-
, C
OUT
,