LED7707 STMicroelectronics, LED7707 Datasheet - Page 37

• Manufacturer Part Number: LED7707
• Description: LED Drivers 6-ROW 85mA LED DRIV BOOST REG LCD PANEL
• Manufacturer: STMicroelectronics

Specifications of LED7707

• High Level Output Current: 85 mA
• Operating Supply Voltage: 4.5 V to 36 V
• Maximum Supply Current: 1 mA
• Maximum Power Dissipation: 2.3 W
• Maximum Operating Temperature: + 150 C
• Mounting Style: SMD/SMT
• Package / Case: VFQFPN-24
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

LED7707
Note:
In order to estimate also the efficiency, other contributions to the power dissipation must be
added to P
Equation 47
where V
Equation 48
where DCR = 80 mΩ (typical DCR of the recommended inductors).
Therefore the total dissipated power is:
Equation 49
Considering the input power as the result of input voltage multiplied by the input current, the
estimated efficiency is:
Equation 50
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
P
tot
=
IN
+
V
⋅
−
I
, F
P
2
Ind
P
P
Diode
DISS
DISS
,
IN
RMS
,
Diode
,
⋅
TOT
I
≅
IN
DCR
⋅
+
D
=
P
2
. 0
DISS
=
⋅
862
I
2
IN
133
,
Ind
=
mW
63
=
. 1
mW
316
Application information
W
37/47