NCP5623B Datasheet, PDF (10/11 Pages) ON Semiconductor – Triple Output I2C Controlled RGB LED Driver

NCP5623B
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PWM OPERATION
The built−in PWM are fully independent and can be
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programmed to any value during the normal operation of the
NCP5623B chip. The PWM operate with five bits, yielding
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a 32 steps range to cover the full modulation (0 to 100%) of
the associated LED:
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− PWM = $00 ³ the associated LED is fully OFF,
whatever be the programmed ILED value
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− PWM > $00 but < $1F ³ the brightness of the
associated LED is set depending upon the PWM
5
modulation value
− PWM = $1F ³ the associated LED is fully ON, the
0
0
5
10
15
20
25
30
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current being the one defined by the ILED value.
Each PWM is programmable, via the I2C port as depicted,
Step
at any time under any sequence arrangement as requested by
Figure 4. Output Current Programmed
the end system’s designer. The PWM does not change the
Value ( ILED = F(Step) )
ILED value, but merely modulate the ON/OFF ratio of the
associated LED. Each step of the PWM represent 100/32 =
3.125% of the full range, the clock being 2.1 kHz (typical).
100
90
Vf = 2.85 V
80
Vf = 3.8 V
70
60
50
40
2.5
3.0
3.5
4.0
4.5
V_BAT (V)
Figure 5. NCP5623B Typical Efficiency as a Function of the Vf
NOTE: Efficiency is measured with the three PWM equal to 100%
+Vcc
MCU
I2C Port
GND
+Vbat
1 mF/6.3 V
C1
GND
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SDA
7
SCL
9
6
GND R1 ₈
62 k
GND
C3
220 nF
1
12
C1P
Vbat
C1N
Vout
SDA
LED3
SCL
LED2
AGND
LED1
IREF
GND
NCP5623B
U1
C2
1 mF/10 V
10
GND
3
D3
4
D2
5
2
D1
GND
Figure 6. Basic RGB Application
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