Datasheet U2010B (Atmel) - 6

link to page 2 link to page 12 link to page 13
3.7 Load-current Compensation
The circuit continuously measures the load current as a voltage drop at resistance R . The eval- 6 uation and use of both half waves results in a quick reaction to load-current change. Due to the voltage at resistance R , there is a difference between both input currents at pins 1 and 2. This 6 difference controls the internal current source, whose positive current values are available at pins 5 and 6. The output current generated at pin 5 contains the difference from the load-current detection and from the mains voltage compensation, see Figure 1-2 on page 2. The efficient impedance of the set-point network generates a voltage at pin 4. A current, flowing out of pin 5 through R , modulates this voltage. An increase of mains voltage causes the 10 increase of control angle α, an increase of load current results in a decrease in the control angle. This avoids a decrease in revolution by increasing the load as well as an increase of revolution by the increment of the mains supply voltage.
3.8 Load-current Limitation
The total output load current is available at pin 6. It results in a voltage drop across R . When 11 the potential of the load current reaches about 70% of the threshold value (V ), i.e., about T70 4.35V at pin 6, it switches the high-load comparator and opens the switch between pins 11 and 12. By using an LED between these pins (11 and 12), a high-load indication can be realized. If the potential at pin 6 increases to about 6.2V (= V ), it switches the overload comparator. T100 The result is programmable at pin 9 (operation mode).
3.8.1 Mode Selection
a) α (V = 0) max 9 In this mode of operation, pin 13 switches to –V (pin 11) and pin 6 to GND S (pin 10) after V has reached the threshold V . A soft-start capacitor is then 6 T100 shorted and the control angle is switched to α . This position is maintained max until the supply voltage is switched off. The motor can be started again with the soft-start function when the power is switched on again. As the overload condition switches pin 13 to pin 11, it is possible to use a smaller control angle, α , by max connecting a further resistance between pins 13 and 14. b) Auto start (pin 9 – open), see Figure 7-8 on page 12 The circuit behaves as described above, with the exception that pin 6 is not connected to GND. If the value of V6 decreases to 25% of the threshold value (V ), the circuit becomes active again with soft start. T25 c) I (V = V ), see Figure 7-10 on page 13 max 9 8 When V has reached the maximum overload threshold value (i.e., V = V ), 6 6 T100 pin 13 is switched to pin 8 (V ) through the resistance R (= 2kΩ) without the Ref soft-start capacitor discharging at pin7. With this mode of operation, direct load-current control (I ) is possible. max
6 Atmel U2010B
4766D–INDCO–03/11 Document Outline Features Applications 1. Description 2. Pin Configuration 3. General Description 3.1 Mains Supply 3.2 Voltage Monitoring 3.3 Phase Control 3.4 Automatic Retriggering 3.5 Current Synchronization 3.6 Voltage Synchronization with Mains Voltage Compensation 3.7 Load-current Compensation 3.8 Load-current Limitation 3.8.1 Mode Selection 4. Absolute Maximum Ratings 5. Thermal Resistance 6. Electrical Characteristics 7. Diagrams 8. Ordering Information 9. Package Information 10. Revision History