Electronic Components Datasheet Search |
|
ADP3611JRMZ-REEL Datasheet(PDF) 10 Page - ON Semiconductor |
|
ADP3611JRMZ-REEL Datasheet(HTML) 10 Page - ON Semiconductor |
10 / 13 page ADP3611 http://onsemi.com 10 polarity reversal of the inductor current to maximize light load conversion efficiency. DRVLSD can also be pulled low for reverse voltage protection purposes. When DRVLSD is low, the low-side driver stays low. When DRVLSD is high, the low-side driver is enabled and controlled by the driver signals, as previously described. Low−Side Driver Timeout In normal operation, the DRVH signal tracks the IN signal and turns off the Q1 high-side switch with a few 10 ns delay (tpdlDRVH) following the falling edge of the input signal. When Q1 is turned off, DRVL is allowed to go high, Q2 turns on, and the SW node voltage collapses to zero. But in a fault condition such as a high-side Q1 switch drain-source short circuit, the SW node cannot fall to zero, even when DRVH goes low. The ADP3611 has a timer circuit to address this scenario. Every time the IN goes low, a DRVL on-time delay timer is triggered. If the SW node voltage does not trigger a low-side turn-on, the DRVL on-time delay circuit does it instead, when it times out with tSW(TO) delay. If Q1 is still turned on, that is, its drain is shorted to the source, Q2 turns on and creates a direct short circuit across the VDCIN voltage rail. The crowbar action causes the fuse in the VDCIN current path to open. The opening of the fuse saves the load (CPU) from potential damage that the high-side switch short circuit could have caused. Crowbar Function In addition to the internal low-side drive time-out circuit, the ADP3611 includes a CROWBAR input pin to provide a means for additional overvoltage protection. When CROWBAR goes high, the ADP3611 turns off DRVH and turns on DRVL. The crowbar logic overrides the overlap protection circuit, the shutdown logic, the DRVLSD logic, and the UVLO protection on DRVL. Thus, the crowbar function maximizes the overvoltage protection coverage in the application. The CROWBAR can be either driven by the CLAMP pin of buck controllers, such as the ADP3207A, or ADP3210, or controlled by an independent overvoltage monitoring circuit. Table 5. ADP3611 Truth Table CROWBAR UVLO SD DRVLSD IN DRVH DRVL L L H H H H L L L H H L L H L L H L H H L L L H L L L L L L L * * L L L H * * * L L H L * * * L H H H * * * L H * = Don’t Care APPLICATION INFORMATION Supply Capacitor Selection For the supply input (VCC) of the ADP3611, a local bypass capacitor is recommended to reduce the noise and to supply some of the peak currents drawn. Use a 10 mF or 4.7 mF multilayer ceramic (MLC) capacitor. MLC capacitors provide the best combination of low ESR and small size, and can be obtained from the following vendors. Table 6. Vendor Part Number Web Address Murata GRM235Y5V106Z16 www.murata.com Taiyo−Yuden EMK325F106ZF www.t−yuden.com Tokin C23Y5V1C106ZP www.tokin.com Keep the ceramic capacitor as close as possible to the ADP3611. Bootstrap Circuit The bootstrap circuit uses a charge storage capacitor (CBST) and a synchronous MOSFET rectifier (D1), as shown in Figure 18. Selection of these components can be done after the high-side MOSFET has been chosen. The bootstrap capacitor must have a voltage rating that is able to handle at least 5 V more than the maximum supply voltage. The capacitance is determined by CBST + QHSGATE DVBST (eq. 1) where: QHSGATE is the total gate charge of the high-side MOSFET. DVBST is the voltage droop allowed on the high-side MOSFET drive. For example, two NTMFS4821N MOSFETs in parallel have a total gate charge of about 20 nC. For an allowed droop of 100 mV, the required bootstrap capacitance is 200 nF. A good quality ceramic capacitor should be used, and derating for the significant capacitance drop of MLCs at high temperature must be applied. In this example, selection of 470 nF or even 1 mF would be recommended. Normally a Schottky diode is recommended for the bootstrap diode due to its low forward drop, which maximizes the drive available for the high-side MOSFET. Using a synchronous MOSFET rectifier instead of a Schottky diode has the advantage of an even lower forward voltage drop. A lower forward voltage drop gives a larger drive voltage for the high-side MOSFET and a lower conduction loss for the high-side MOSFET. The bootstrap diode must also be able to handle at least 5 V more than the maximum battery voltage. The average forward current can be estimated by IF(AVG) + QHSGATE fMAX (eq. 2) where fMAX is the maximum switching frequency of the controller. |
Similar Part No. - ADP3611JRMZ-REEL |
|
Similar Description - ADP3611JRMZ-REEL |
|
|
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 |