Electronic Components Datasheet Search |
|
TOP234P Datasheet(PDF) 9 Page - Power Analog Micoelectronics |
|
TOP234P Datasheet(HTML) 9 Page - Power Analog Micoelectronics |
9 / 36 page TOP232-234 B 7/01 9 for line sensing by connecting a resistor from this pin to the rectified DC high voltage bus to implement OV, UV and DC MAX reduction with line voltage functions. In this mode, the value of the resistor determines the line OV/UV thresholds, and the DC MAX is reduced linearly with rectified DC high voltage starting from just above the UV threshold. In high efficiency applications this pin can be used in the external current limit mode instead, to reduce the current limit externally to a value close to the operating peak current, by connecting the pin to the SOURCE pin through a resistor. The same pin can also be used as a remote on/off and a synchronization input in both modes. Please refer to Table 2 for possible combinations of the functions with example circuits shown in Figure 13 through Figure 23. A description of specific functions in terms of the MULTI- FUNCTION pin I/V characteristic is shown in Figure 8. The horizontal axis represents MULTI-FUNCTION pin current with positive polarity indicating currents flowing into the pin. The meaning of the vertical axes varies with functions. For those that control the on/off states of the output such as UV, OV and remote ON/OFF, the vertical axis represents the enable/ disable states of the output. UV triggers at I UV (+50 µA typical) and OV triggers at I OV (+225 µA typical). Between +50 µA and +225 µA, the output is enabled. For external current limit and line feed forward with DC MAX reduction, the vertical axis represents the magnitude of the I LIMIT and DCMAX. Line feed forward with DC MAX reduction lowers maximum duty cycle from 78% at I M(DC) (+90 µA typical) to 38% at IOV (+225 µA). External current limit is available only with negative MULTI-FUNCTION pin current. Please see graphs in the typical performance characteristics section for the current limit programming range and the selection of appropriate resistor value. FREQUENCY (F) Pin Operation The FREQUENCY pin is a digital input pin available in TO-220 package only. Shorting the FREQUENCY pin to SOURCE pin selects the nominal switching frequency of 132 kHz (Figure 10) which is suited for most applications. For other cases that may benefit from lower switching frequency such as noise sensitive video applications, a 66 kHz switching frequency (half frequency) can be selected by shorting the FREQUENCY pin to the CONTROL pin (Figure 11). In addition, an example circuit shown in Figure 12 may be used to lower the switching frequency from 132 kHz in normal operation to 66 kHz in standby mode for very low standby power consumption. MULTI-FUNCTION (M) Pin Operation When current is fed into the MULTI-FUNCTION pin, it works as a voltage source of approximately 2.6 V up to a maximum current of +400 µA (typical). At +400 µA, this pin turns into a constant current sink. When current is drawn out of the MULTI-FUNCTION pin, it works as a voltage source of approximately 1.32 V up to a maximum current of –240 µA (typical). At –240 µA, it turns into a constant current source. Refer to Figure 9. There are a total of five functions available through the use of the MULTI-FUNCTION pin: OV, UV, line feed forward with DC MAX reduction, external current limit and remote ON/OFF. A short circuit between the MULTI-FUNCTION pin and SOURCE pin disables all five functions and forces TOPSwitch-FX to operate in a simple three terminal mode like TOPSwitch-II. The MULTI-FUNCTION pin is typically used ✔ ✔✔ ✔ ✔✔ ✔ ✔✔ ✔ ✔✔ ✔ ✔ ✔ ✔✔✔ ✔ Table 2. Typical MULTI-FUNCTION Pin Configurations. MULTI-FUNCTION PIN TABLE* 13 14 15 16 17 18 19 20 21 22 23 *This table is only a partial list of many MULTI-FUNCTION pin configurations that are possible. Using FREQUENCY and MULTI- FUNCTION Pins Figure Number Three Terminal Operation Under-Voltage Overvoltage Line Feed Forward (DC MAX) Line Feed Forward (I LIMIT) External Current Limit Remote ON/OFF |
Similar Part No. - TOP234P |
|
Similar Description - TOP234P |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.NET |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |