Datasheet

LED7707 Application information
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Equation 22
where n
ROWs
is the number of active rows, ΔV
f,LEDs
is the spread of the LEDs forward
voltage and n
LEDs
is the number of LEDs per row.
d) LDO losses, due to the dissipation of the 5 V linear regulator:
Equation 23
The LED7707 is housed in a 24 leads 4x4-VFQFPN package with exposed pad that allows
good thermal performance. However it is also important to design properly the
demonstration board layout in order to assure correct heat dissipation.
Figure 20 shows a picture of the LED7707 application demonstration board taken using an
infrared camera. The chip temperature, in those application conditions, is kept below 50 °C.
Figure 20. Demonstration board thermographic analysis
(
)
(
)
DIMLEDsLEDs,fIFBROWsROWGEN
DnVV1nIP
⋅
⋅
Δ
+
⋅
−
⋅
=
(
)
LDOLDOINLDO,D
IVVP
⋅
−
=

64°C 50°C
V
IN
= 12V
I
ROW
= 60mA
V
OUT
= 30V
F
SW
= 660kHz
D
DIM
= 100%
T
amb
= 25°C
64°C 50°C
V
IN
= 12V
I
ROW
= 60mA
V
OUT
= 30V
F
SW
= 660kHz
D
DIM
= 100%
T
amb
= 25°C