LED7707TR STMicroelectronics, LED7707TR Datasheet - Page 35

• Manufacturer Part Number: LED7707TR
• Description: IC LED DRIVR WHT BCKLT 24-VFQFPN
• Manufacturer: STMicroelectronics
• Type: Backlight, White LEDr

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

LED7707
6.4.6
6.4.7
6.4.8
Over-voltage protection divider setting
The over-voltage protection (OVP) divider provides a partition of the output voltage to the
OVSEL pin. The OVP divider setting not only fixes the OVP threshold, but also the open-
channel detection threshold.
The proper OVP divider setting can be calculated by the equation (3):
Equation 38
where V
the maximum V
Equation 39
R
the resistor divider. For example, setting R
standard commercial value is R
Compensation network
For the compensation network, the suggestions provided in
In this condition, tentatively the following value of R3 and C8 (see
good choice for the loop stability:
R3 = 2.4 kΩ
C8 = 4.7 nF
Boost current limit
The boost current limit is set to protect the internal power switch against excessive current.
The slope compensation may reduce the programmed current limit. Hence, to take into
account this effect, as a rule of thumb, the current limit can be set as twice as much the
maximum inductor peak current (see
I
Therefore, using equation (7) and choosing I
Equation 40
BOOST, PEAK
1
can be chosen is in the order of hundreds of kilo-ohms to reduce the leakage current in
OUT, MAX
> 3.83 A
F
is the maximum output voltage considering the worst case (all LEDs with
= V
F,max
V
OUT
= 3.7 V on the same row):
R
,
OVP
2
R
2
=
BILIM
= 22 kΩ.
=
R
nLED
1
⋅
Section 6.4.4
=
V
I
OUT
BOOST
⋅
1
V
,
MAX
= 510 kΩ leads to R
K
, F
BOOST, PEAK
max
B
,
PEAK
. 1
+
145
+
4
):
V
700
=
V
−
300
. 1
mV
145
= 4 A, R
k
Ω
=
Section 6.1
V
26
6 .
2
V
BILIM
= 21.89 kΩ. The closest
Figure 24
Application information
will be:
are always valid.
) are usually a
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