13-3
2-2 Operations on Each Terminal of STR-M6511 and
Associated Circuits
2-2-1 VIN Terminal (pin 5) and Start Circuit
The start circuit detects a voltage at VIN terminal (pin 5) and
controls start and stop of the control IC.
The power of control IC (VIN terminal input) uses a circuit
shown in Fig. 13-4.
Power start:
When the VIN 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 100µA max. (VIN = 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 ND of the transformer
TQ01 is detected and smoothed with DQ05 and CQ15. Thus
obtained voltage is fed to the VIN terminal (pin 5).
Since the voltage does not reach the specified voltage level
after operation of the control circuit, the VIN 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 VIN terminal voltage reaches the
setting value, thus, the control circuit continues the operation.
Fig. 13-6 shows a VIN 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
To Next Page
Loading...
