XC9116B02ADL TOREX [Torex Semiconductor], XC9116B02ADL Datasheet - Page 8

• Manufacturer Part Number: XC9116B02ADL
• Description: Step-Up DC/DC Converter-Backlight LED Driver
• Manufacturer: TOREX [Torex Semiconductor]

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■APPLICATION INFORMATION (Continued)
<Prevent Emission Caused by White LEDs Leakage>
<Dimming Control (Continued)>
3. Using DC Voltage
XC9116
When the input voltage (V
happens, please connect a transistor to between the LED and the FB pin. By driving the CE signal in-phase and cutting
the pass to current, the minimum illumination can be prevented.
If in an application it is necessary to control the LED current by a variable DC voltage, illumination control of LED is
achieved by connecting R1 and R2 and applying a direct-current voltage to R2, as shown below.
When R1>>R
I
V
LED
Ex.1) When R1 = 10k
Ex.2) When R1 = 10k
REF
= 0.2V (TYP.)
In the range of 0.2V to 2.2V DC, I
(LED current) varies between 20mA to 0mA.
= (V
C1 = 0.1µF, RLED = 10Ω, the average LED current will
be 10mA by inputting a PWM signal of CE ‘H’ level:
2.2V, CE ’L’ level: 0V, duty cycle: 50%, oscillation
frequency: 100Hz.
control by applying the PWM signal to the CE pin, the
average LED current increases proportionally with the
positive duty cycle of the PWM signal.
REF
LED
- R1 / R2 (V
, I
LED
Series
VIN
(3.2V~6.0V)
which flows into LEDs can be calculated by the following equation;
3.6V
Ω
Ω
, R2 = 100k
, R2 = 100k
IN
4.7uF
CIN
DC
) is high, minimum illumination may occur to the CE pin even in the disable state. If this
As well as the way of dimming
- V
REF
Ω
Ω
)) / R
, R
, R3 = 10k
LED
LED
LED
= 10
CE
VIN
Ω
VLF3010A
Ω
,
L:22uH
,
GND
Lx
FB
XB0ASB03A1B
Figure : Circuit inputting a PWM signal to the FB pin
RLED
SD
10Ω
PWM
VDC
XP151A21A2
C1
R3
Figure : Circuit using DC voltage
20mA
R2
R2
XC9116
XC9116
FB
FB
0.22uF
(base)
CL
ZD
(
ZD
(
ILED
ILED
)
)
R1
R1
RLED
RLED