U2010B-MFP Datasheet, PDF (5/18 Pages) ATMEL Corporation – Phase-control IC with Current Feedback and Overload Protection

U2010B
Current Synchronization
Current synchronization fulfils two functions:
– Monitoring the current flow after triggering.
In case the triac extinguishes again or does not switch on, automatic
triggering is activated until the triggering is successful.
– Avoiding triggering due to an inductive load.
In the case of inductive load operation, the current synchronization ensures
that in the new half wave, no pulse will be enabled as long as there is a
current available from the previous half wave, which flows from the opposite
polarity to the actual supply voltage.
Th current synchronization as described above is a special feature of the U2010B. The
device evaluates the voltage at the pulse output between gate and reference electrode
of the triac. As a result, no separate current synchronization input with specified series
resistance is necessary.
Voltage Synchronization
with Mains Voltage
Compensation
The voltage detector synchronizes the reference ramp with the mains supply voltage. At
the same time, the mains-dependent input current at pin 15 is shaped and rectified inter-
nally. This current activates the automatic retriggering and at the same time is available
at pin 5. By suitable dimensioning, it is possible to obtain the specified compensation
effect. Automatic retriggering and mains voltage compensation are not activated until
½V_{15 - 10}½ increases to 8 V. The resistance R_sync. defines the width of the zero voltage
cross over pulse, synchronization current, and hence the mains supply voltage compen-
sation current.
Figure 4. Suppression of Mains Voltage Compensation and Retrigger Automatic
Mains
R₂
2x
C6V2
15
U2010B
10
Load-current
Compensation
If the mains voltage compensation and the automatic retriggering are not required, both
functions can be suppressed by limiting ½V_{15 - 10}½ £ 7 V, see Figure 4.
The circuit continuously measures the load current as a voltage drop at resistance R₆.
The evaluation and use of both half waves results in a quick reaction to load-current
change. Due to the voltage at resistance R₆, there is a difference between both input
currents at pins 1 and 2. This difference controls the internal current source, whose pos-
itive 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 com-
pensation, see Figure 2 on page 2.
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4766A–INDCO–01/04