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TDA16846-2 データシート(PDF) 10 Page - Infineon Technologies AG |
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TDA16846-2 データシート(HTML) 10 Page - Infineon Technologies AG |
10 / 29 page TDA 16846/16846-2 TDA 16847/16847-2 Version 2.0 10 31 Jul 2003 Fold Back Point Correction PVC (Pin 11) V 11 is derived from a voltage divider connected to the rectified mains and reduces the limit of the possible current maximum in the power transistor if the mains voltage increases. I.e. this limit is independent of the mains (only active in free running mode). The maximum current ( I Mprimary) depending on the voltage V11 at Pin 11 is : Off-Time Circuit OTC (Pin 1) Figure 6 shows the Off-Time Circuit which determines the load dependent frequency curve. When the driver switches off (Figure 7) the capacitor C 1 is charged first by current I 1L (approx. 0.5 mA, for extended ringing suppression time). As soon as the voltage at pin 3 reaches the level V 3L (2.5 V), the charging current is switched to the higher value I 1H (approx. 1 mA, for normal ringing suppression time). This current flows until the capacitor’s voltage reaches 3.5 V. The charge time TC1 is : For proper operation of the special internal anti- jitter circuit, TC1 (rising time for I 1H only) should have the same value as the resonance time “tR” of the power circuit (Figure 7). After charging C 1 up to 3.5 V the current source is disconnected and C1 is discharged by resistor R 1. The voltage V1 at Pin 1 is applied to the Off-Time Comparator (OFTC). The other input of OFTC is the control voltage. The value of the control voltage at the input of OFTC is limited to a minimum of 2 V (for stable frequency at very light load). The On- Time Flip Flop (ONTF) is set, if the output of OFTC is high 1) and the voltage V 3 at Pin 3 falls below 25 mV (zero crossing signal is high). This ensures switching on of the power transistor at minimum voltage. If no zero crossing signal is coming into pin 3, the power transistor is switched on after an additional delay until V 1 falls below 1.5 V (see Figure 6, OFTCD). As long as V 1 is higher than the limited control voltage, ONTF is disabled to suppress wrong zero crossings of V 3, due to parasitic oscillations from the transformer after switch-off. The discharge time of C 1 is a function of the control voltage. 1) i.e. V 1 is less than the limited control voltage. . Control Voltage Output Power Off-time TD1 1.5 - 2 V Low Constant (TD1 MAX.), const. frequency stand by 2 - 3.5 V Medium Decreasing 3.5 - 5 V High Free running, switch-on at first minimum IMprimary 4V V 11 3 ⁄ – () R 2 C 2 × × Lprimary ------------------------------------------------------------ = TC1 C1 1,5 V × 1mA ------------------------- ≈ |
同様の部品番号 - TDA16846-2 |
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同様の説明 - TDA16846-2 |
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