1 3 - 3
2-2 Operations on Each Terminal of STR-M6511 and
Associated Circuits
2-2-1 V
IN
Terminal (pin 5) and Start Circuit
The start circuit detects a voltage at V
IN
terminal (pin 5) and
controls start and stop of the control IC.
The power of control IC (V
IN
terminal input) uses a circuit
shown in Fig. 13-4.
Power start:
When the V
IN
terminal voltage reaches 16V (TYP) by
charging CQ15 through starting resistors RQ02 and RQ03,
the control circuit begins operating.
The circuit current is suppressed to 100
µ
A max. (V
IN
= 14V,
TC = 25°C) until the control circuit begins operating, so
RQ02 and RQ03 can take higher resistance values.
After operation of the control circuit:
A voltage induced across subwinding N
D
of the transformer
TQ01 is detected and smoothed with DQ05 and CQ15. Thus
obtained voltage is fed to the V
IN
terminal (pin 5).
Since the voltage does not reach the specified voltage level
after operation of the control circuit, the V
IN
terminal voltage
begins to drop. But as the operation stop voltage is set to a low
voltage of 10V (TYP), the subwinding voltage reaches the
setting value before the V
IN
terminal voltage reaches the
setting value, thus, the control circuit continues the operation.
Fig. 13-6 shows a V
IN
terminal voltage waveform at starting
period.
DQ01
TQ01
CQ04
RQ02
RQ03
DQ05
CQ15
N
D
GND
VIN
1
5
3
N
P
QQ01
STR-M6511
From AC input
filter circuit
Fig. 13-3
Start circuit
V
IN
10V
(TYP)
16V
(TYP)
Aux power voltage
Control circuit operation start
Fig. 13-5
V
IN
terminal voltage waveform at
starting period
QQ03
QQ02
200
Ω
O.S.C
R2
6
C1
C2
R3
Amp teminal
RQ14
From Regulator
circuit
Fig. 13-6
Fig. 13-4
V
IN
terminal voltage and circuit
current I
IN
I
IN
14mA
(TYP)
100µA
(TYP)
10V
(TYP)
14V 16V
(TYP)
V
IN
