Supervision Circuit For Thermal Head Temperature - Panasonic KX-F900 Service Manual

r KX-F900 ]
3-4. SUPERVISION CIRCUIT FOR THERMAL HEAD TEMPERATURE
(1) Function
Thermal head temperature is disposed to convert voltage to digital data by using A!D converter of IC1. The CPU decides
the strobe width of the thermal head according to this value. Therefore, this circuit can keep the thermal head at an even
temperature in order to stabilize the printing density and prevent the head from being overheated.
Circuit Diagram
TH-
HEAD
r ......
t C37
R47 _ __y¢l-__
R48
R49
/
28
i
_, 27
\ 26
\ 25
\ 22
\ 24
\ 23
49
C39
38
STB1
STB2
STB3
STB4
THDAT
THCLK
THLAT
ADSEL1
AIN2
IC1
Timing Chart
I
Effective signal
©
1.5V
ref LEVEL CLAMP
IC1 internal bias
CLAMP
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N i
:;Ol
t"_l
C:l
m ,
OI
"Ol
I1"11
21
Ol
135-