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Figure 19 shows KEYB_DRV output connectivity:
3.9.2.2
BL_SINK
The c18 BL_SINK output is an open drain current sink. Therefore, the LEDs' anode must be tied to VCC and the cathode to the
c18 BL_SINK pin. The programmable current sink operates between 0 mA and 40 mA in 16 steps through the SBI register
DRV_LCDSEL. The default current is set to 0 mA. These programmable currents are used to control the brightness of the LCD
backlight.
Like the keyboard backlight driver, when the sink current is programmed for 0 mA (default), the open drain output is at a high
impedance state.
This feature is available only on c18 models using a 70-pin interface connector.
An external driver should be implemented if higher drive currents are required.
Note
This driver is hardware supported.
Figure 20 shows BL_SINK output connectivity:
98-08901C63-A
c18
Figure 19. KEYB_DRV Output Connectivity
c18
Figure 20. BL_SINK Output Connectivity
Vcc
Pin #70
KEYB_DRV
Vcc
Pin #27
BL_SINK
Hardware Description
35
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