ncp5890 ON Semiconductor, ncp5890 Datasheet - Page 12

• Manufacturer Part Number: ncp5890
• Description: Light Management Ic Dedicated For Lcd Backlighting And Multi-led Fun Light Applications
• Manufacturer: ON Semiconductor

Keyboard Dimming
dynamic independent control of three sets of LED. Each PWM is associated with a register, the IC port being used to update
the pulse modulation as requested by the application.
PWM0[7..0] PWM0 Modulation
Bits [B7:B5] : RFU, Bits [B4:B0] : PWM0 setup
PWM1[7..0] : PWM1 Modulation
Bits [B7:B5] : RFU, Bits [B4:B0] : PWM1 setup
PWM2[7..0] : PWM2 Modulation
Bits [B7:B5] : RFU, Bits [B4:B0] : PWM2 setup
Backlight Dimming
internal register ILEDREG[7:0] is set up by the content of the SDA byte send by the external MCU. For typical application,
the 100 mA reference current forced by the external resistor yields a 25 mA maximum in the output LED. The waveforms
given illustrate a normal programming sequence.
ILEDREG[0..7]
[B7:B6] = RFU
[B4..B0] = Output LED mA/step current. The content of these bits is latched to the current reference on the 8
The keyboard shares the same I−LED peak current with the backlight, but the built−in PWM structure makes possible a
The built−in I2C interface provides a simple way to accurately control the output peak current flowing in the LED. The
RESET
RESET
RESET
RESET
Figure 10. Typical Gradual Dimming UPWARD
step
%
%
%
B7
B7
B7
B7
0
0
0
0
0
0
0
0
B6
B6
B6
B6
0
0
0
0
0
0
0
0
B5
B5
B5
B5
0
0
0
0
0
0
0
0
http://onsemi.com
ILED16
B4
B4
B4
B4
50
50
50
12
0
0
0
0
Figure 11. Typical Gradual Dimming DOWNWARD
ILED8
B3
B3
B3
B3
25
25
25
0
0
0
0
ILED4
12.5
12.5
12.5
B2
B2
B2
B2
0
0
0
0
ILED2
6.25
6.25
6.25
B1
B1
B1
B1
0
0
0
0
th
SCL clock pulse.
ILED1
3.125
3.125
3.125
B0
B0
B0
B0
0
0
0
0