STEVAL-ILL021V1 STMicroelectronics, STEVAL-ILL021V1 Datasheet - Page 35

• Manufacturer Part Number: STEVAL-ILL021V1
• Description: BOARD EVAL LCD BACKLIGHT LED7707
• Manufacturer: STMicroelectronics

Specifications of STEVAL-ILL021V1

• Design Resources: STEVAL-ILL021V1 Bill of Material STEVAL-ILL021V1 Schematic
• Current - Output / Channel: 85mA
• Outputs And Type: 6, Non-Isolated
• Voltage - Output: 36 V
• Features: Dimmable, Extra 5V Output
• Voltage - Input: 4.5 ~ 36 V
• Utilized Ic / Part: LED7707
• Description/function: LCD backlight demonstration board
• Operating Voltage: 4.5 V to 36 V
• Product: Display Modules
• Core Chip: LED7707
• No. Of Outputs: 1
• Output Voltage: 36V
• Dimming Control Type: PWM
• Mcu Supported Families: LED7707
• Lead Free Status / RoHS Status: Lead free by exemption / RoHS compliant by exemption
• For Use With/related Products: LED7707
• Other names: 497-10044

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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