Panasonic KX-FT21BX Service Manual page 175

Using a different winding ratio results in the voltage function given by the formula in figure (c).
As you can see, it is possible to keep V
in input voltage.
Response to Variations in Output Current
In this case, V is kept constant by controlling only T
O
variations in output current. Figure B (a) and (b) shows how T
The input current must be increased as output current increases, making T
surface area of the sawtooth waves in this figure by the time interval gives the average input current.
Principle of Constant Voltage Operation Given Variations
in the Output Current Under the RCC Method
constant by changing the ratio of T
O
without changing the ratio between T
ON
varies in response to variations in output current.
ON
I
IN
0
T T
ON OFF
(a) An input current I
IN
I
IN
0
T T
ON OFF
(b) An input current I
IN
<Figure B>
- 149 -
and T in response to variations
ON OFF
ON
longer. The value obtained by dividing the
ON
t
waveform when output current is low
t
waveform when output current is high
KX-FT21LA
and T in response to
OFF