Epson S5U1C17801T1100 Network Router User Manual


 
15 LED/LCD BACKLIGHT CONTROL CIRCUIT WITH MFT0
S5U1C17801T1100 HARDWARE MANUAL
EPSON
37
(SOFTWARE EVALUATION TOOL FOR S1C17801)
15 LED/LCD Backlight Control Circuit
with MFT0
The SVT17801 is equipped with a LED that can be controlled by MFT0. The following diagram shows how the
EEPROM is connected to the SVT17801.
DIC-152-6P
1
1
5
3
5
3
2
6
4
2
4
G V
V
DD
J12 11pin
(LCD backlight)
V
DD
JP3
JP3
MFT0
U20
TS5A3166
R90
470
LED3
LT
W-170TK
C65
0.1µF
LCD_BL_ON
LCD_BL_PWM
D201_PWM
S1C17801
Fig. 15.1 Connection Circuit between MFT0 and LED/LCD Backlight
Pre-stage switching IC (TS5A3166) is switched by changing phase in MFT0 H/L areas, and brightness of the LED
can be changed visually by turning ON and OFF the backlight of LED and LCD panel repeatedly in accordance
with the MFT0 phase.
MFT0 is an I/O port with 12 mA of drive current. A circuit shown in the figure 15.1.has a pre-stage switch IC,
which however can be replaced simply by a 470
Ω resistor for direct drive. (The drive current in this case is ap-
proximately 7 mA.)