LED7707TR STMicroelectronics, LED7707TR Datasheet - Page 34
![IC LED DRIVR WHT BCKLT 24-VFQFPN](/photos/7/37/73763/led7707tr_sml.jpg)
LED7707TR
Manufacturer Part Number
LED7707TR
Description
IC LED DRIVR WHT BCKLT 24-VFQFPN
Manufacturer
STMicroelectronics
Type
Backlight, White LEDr
Datasheet
1.LED7707TR.pdf
(47 pages)
Specifications of LED7707TR
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
Operating Temperature
0°C ~ 85°C
Current - Output / Channel
85mA
Internal Switch(s)
Yes
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
Minimum Operating Temperature
- 40 C
For Use With
497-10044 - BOARD EVAL LCD BACKLIGHT LED7707
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Efficiency
-
Lead Free Status / Rohs Status
Details
Other names
497-8492-2
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Company:
Part Number:
LED7707TR
Manufacturer:
ST
Quantity:
12 000
Company:
Part Number:
LED7707TR
Manufacturer:
STMicroelectronics
Quantity:
10 000
Application information
6.4.5
34/47
T
Equation 35
defining D
Equation 36
The worst case for the output voltage ripple is when input voltage is lower (V
A simple way to select the C
In order to affect as less as possible the current generators, it would be better to fix the
maximum ripple lower than the typical voltage across the generators.
For example considering ΔV
leading generator), the required capacitance is:
Equation 37
A margin from the calculated value should be taken into account because of the
capacitance drop due to the applied voltage when MLCCs are used.
One 10 µF MLCC (or two 4.7 µF MLCCs) can be a good choice for this application.
In case a dimming duty cycle different from 100% is used, a further contribution to the
capacitor discharge (during the off time of the dimming cycle) should be considered.
Input capacitor choice
The input capacitor of a boost converter is less critical than the output capacitor, due to the
fact that the inductor is in series with the input, and hence, the input current waveform is
continuous.
A low ESR capacitor is always recommended.
A capacitor of 10 µF is tentatively a good choice for most of the applications.
OFF
can be calculated as:
2
as:
D
T
2
OFF
=
=
C
2
OUT
OUT
R
T
OUT
⋅
SW
F
0
SW
⋅
lower than 70 mV (i.e. the 10 % of the voltage across the
value is fixing a maximum voltage ripple.
(
⋅
M
>
D
⋅
L
(
−
2
I
, L
⋅
1
=
peak
M
)
2
⎧
⎨
⎩
Δ ⋅
618
569
=
−
⎧
⎨
⎩
V
I
. 0
. 0
OUT
OUT
2 .
7 .
408
376
ns
ns
,
max
)
⋅
T
@
@
OFF
@
@
V
=
V
V
V
IN
IN
. 6
IN
IN
,
,
max
min
,
,
33
max
min
μ
=
=
=
F
=
10
13
10
13
8 .
2 .
8 .
2 .
V
V
V
V
IN,min
= 10.8 V).
LED7707