Electronic Components Datasheet Search |
|
FA5314PS Datasheet(PDF) 10 Page - Fuji Electric |
|
FA5314PS Datasheet(HTML) 10 Page - Fuji Electric |
10 / 17 page 10 FA531X series (2) Startup circuit connected to rectified line This method is not suitable for FA531X, especially concerned with re-startup operation just after power-off or startup which AC input voltage goes up slowly. Fig. 21 shows a startup circuit that a startup resistor RA is connected to rectified line directly. The period from power-on to startup is determined by RA, RB and CA. RA, RB and CA must be designed to satisfy the following equations. dVcc/dt(V/s)= (1/CA)•{( VIN –Vccon )/RA– Vccon/RB–Iccst } > 1.8/(Cs( µF))..........................................(8) RA(k Ω) < ( VIN– 9.2(V) )/{ 0.4(mA) + ( 9.2(V)/RB(kΩ) ) }....(9) VIN : 2 • (AC input effective voltage) After power-off, once VCC falls down below OFF threshold voltage, VCC rises up again and re-startup occurs while the capacitor C1 is discharged until approximately zero because VCC voltage rises up by the current flowing RA. This operation is repeated several times. After the repeated operation, IC stops in the condition that VCC voltage is equal to Vccon (=ON threshold) because capacitor C1 is discharged gradually and the decreased VCC inclination is out of the condition required by equation (4). After that, re- startup by power-on can not be guaranteed even when equation (8) is satisfied. The image of that the startup is impossible is shown in Fig. 22. It is necessary to startup IC that supply current Icc(startup) to VCC is over 4mA in the condition of Tj < 100 °C during Vcc is kept at Vccon( 16V, balance state at Vccon after the repeated operation. Icc(start-up) > 4mA at Vcc=Vccon, Tj<100 °C, after power-off This balance state that startup is impossible tends to occur at higher temperature. If power-on is done when Vcc is not kept at Vccon (for example:power-off is done and after enough time that C1 is discharged until Vcc can not be pulled up to Vccon), the IC can startup in the condition given by equation(8). In some cases, such as when the load current of power supply is changed rapidly, you may want to prolong the hold time of the power supply output by means of maintaining Vcc over the off threshold. For this purpose, connect diode D4 and electrolytic capacitor C4 as shown in Fig. 23. This prolongs the hold time of the power supply voltage Vcc regardless of the period from power- on to startup. Fig. 21 Startup circuit example(2) Fig. 22 A image of waveform when re-startup is impossible Fig. 23 Startup circuit example(3) Startup is impossible Power ON Power OFF Vccon Vccoff Startup is impossible (dVcc/dt <1.8/Cs just before Vcc reaches Vccon). Icc>4mA is necessary for startup at Tj <100 °C and dVcc/dt=0. |
Similar Part No. - FA5314PS |
|
Similar Description - FA5314PS |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.COM |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | 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 |