NCP5010 Datasheet, PDF (15/18 Pages) ON Semiconductor – 500 mW Boost Converter for White LEDs

NCP5010
Analog Dimming Control
When the NCP5010 is in steady state the output voltage
is controlled in order to have 500 mV to the feedback input
(FB pin). The principle of this schematic is bias by a
resistive network R2/R3 the feedback voltage. If not any
signal is put from outside to R2 there is no voltage drop
across R3 and I_OUT = V_FB/R4. When the voltage put to R2
is increasing the loop balance output voltage to get always
500 mV to FB pin. Thereby voltage across R4 decreases
like this the current in the string of LEDs.
V_Bat
2.7 to 5.5 V
C1
4.7 mF 0603
X5R 6.3 V
L1
22 mH
LED
C2
1 mF 0805
X5R 25 V
ENABLE
A2 _{CTRL VOUT} C1
PWM SIGNAL
NCP5010
R1 10 k
C3
470 nF
R3
18 k
R2
100 k
LED
R4
24
Average Network
Select
DC VOLTAGE
L1: TDK VLF4012AT−220MR51
C1: TDK C1608X5R0J475MT
C2: TDK C2012X5R1E105MT
C3: Standard Capacitor
Figure 33. Dimming Control Using a Filtered PWM Signal or a DC Voltage
DC/DC Boost Application
The NCP5010 can be used as DC/DC Boost converter to
deliver constant voltage to powering load like OLED or
LCD biasing. An external resistive network is connected to
sense the output voltage and close the loop.
ǒ Ǔ Vout + 0.5
R1 ) R2
R1
V_Bat
2.7 to 5.5 V
C1
4.7 mF 0603
X5R 6.3 V
L1
22 mH
ENABLE
A2 _CTRL
V_OUT
C1
R
290 k
15 V / 35 mA
C2
2.2 mF 0805
X5R 25 V
NCP5010
L1: TDK VLF4012AT−220MR51
R
C1: TDK C1608X5R0J475MT
10 k
C2: TDK C2012X5R1E225MT
Figure 34. OLED or LCD Bias Supply
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