LED7706 STMicroelectronics, LED7706 Datasheet - Page 36

• Manufacturer Part Number: LED7706
• Description: IC LED DRIVR WHT BCKLT 24-VFQFPN
• Manufacturer: STMicroelectronics
• Type: Backlight, White LEDr

Specifications of LED7706

• Topology: PWM, Step-Up (Boost)
• Number Of Outputs: 6
• Internal Driver: Yes
• Type - Primary: Backlight
• Type - Secondary: White LED
• Frequency: 250kHz ~ 1MHz
• Voltage - Supply: 4.5 V ~ 36 V
• Voltage - Output: 36V
• Mounting Type: Surface Mount
• Package / Case: 24-VFQFN, 24-VFQFPN
• Current - Output / Channel: 30mA
• Internal Switch(s): Yes
• Operating Supply Voltage: 4.5 V to 36 V
• Maximum Supply Current: 1 mA
• Maximum Power Dissipation: 2300 mW
• Maximum Operating Temperature: + 150 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• For Use With: 497-10043 - BOARD EVAL LCD BACKLIGHT LED7706497-8360 - BOARD EVAL FOR LED7707497-6445 - EVALUATION BOARD FOR LED7706
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Operating Temperature: -
• Efficiency: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Application information
Note:
36/46
In order to estimate also the efficiency, other contributions to the power dissipation must be
added to P
Equation 48
where V
Equation 49
where DCR = 80 mΩ (typical DCR of the recommended inductors).
Therefore the total dissipated power is:
Equation 50
Considering the input power as the result of input voltage multiplied by the input current, the
estimated efficiency is:
Equation 51
It is important to remind that the previous calculations consider the worst case, especially for
the power dissipated on the current generators.
Statistical analysis (confirmed by bench measurements) shows that the series connection of
more LEDs on each channel leads to compensation effects.
The hypothesis 3 above mentioned is thus rather unlikely.
Therefore P
F, Diode
D, tot
GEN
= 0.4 V
(which represents only the power dissipated by the device), that is:
is significantly lower and the overall efficiency is typically around 90 %.
P
DISS
P
DISS
,
TOTAL
P
DISS
,
Ind
=
,
=
Diode
η
P
DCR
, D
=
tot
P
=
IN
+
⋅
V
I
P
−
Ind
, F
2
DISS
P
Diode
P
,
RMS
DISS
IN
,
Diode
⋅
,
TOT
≅
I
IN
DCR
⋅
+
D
=
P
2
DISS
. 0
⋅
=
I
845
IN
2
34
,
Ind
=
5 .
11
=
mW
559
2 .
mW
1 .
mW
LED7706