 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
SP7651 Datasheet(PDF) 6 Page - Sipex Corporation |
|
|
|||||||||||||||||||||||||||||
SP7651 Datasheet(HTML) 6 Page - Sipex Corporation |
|
|
6 / 15 page  6 Rev J: 3/4/07 SP765 Wide Input Voltage Range 3A, 900kHz, Buck Regulator © Copyright 2007 Sipex Corporation THEORY OF OPERATION current- limited (+/-50µA) transconduc- tance, there are many ways to compensate the voltage loop or to control the COMP pin externally. Ifasimple,singlepole,singlezero response is desired, then compensation can be as simple as an RC circuit to Ground. If a more complex compensation is required, then the amplifier has enough bandwidth (45° at 4 MHz) and enough gain (60dB) to run Type III compensation schemes with ad- equate gain and phase margins at crossover frequencies greater than 50kHz. The common mode output of the error am- plifier is 0.9V to 2.2V. Therefore, the PWM voltageramphasbeensetbetween.Vand 2.2Vto ensure proper0% to 100% dutycycle capability. The voltage loop also includes two other very important features. One is asynchronous startup mode. Basically, the synchronous rectifier cannot turn on unless the high side NFET has attempted to turn on or the SS pin has exceeded .7V. This featurepreventsthecontrollerfrom“dragging down” the output voltage during startup or in fault modes. The second feature is a 100% dutycycletimeoutthatensuressynchronized refreshing of the BST capacitor at very high duty ratios. In the event that the high side NFET is on for 20 continuous clock cycles, a reset is given to the PWM flip-flop half way through the 21st cycle. This forces GL to rise for the cycle, in turn refreshing the BST capacitor. Power MOSFETs TheSP765containsapairofintegratedlow resistance N MOSFETs designed to drive up to 3A of output current. Maximum output currentcouldbelimitedbythermallimitations of a particular application. The SP765 incorporates a built-in over-temperature protection to prevent internal overheating. GH Voltage GL Voltage V(V IN) 0V -0V -V(Diode) V V(V IN)+V(V CC ) BST Voltage V(V CC ) TIME SWN Voltage VBST VSWN V(V CC) The SP765 can be set to different output voltages. The relationship in the following formula is based on a voltage divider from the output to the feedback pin VFB, which is set to an internal reference voltage of 0.80V. Standard 1% metal film resistors of surface mount size 0603 are recommended. Vout = 0.80V ( R / R2 + ) => Where R1 = 68.1KΩ and for Vout = 0.80V setting, simply remove R2 from the board. Furthermore, one could select the value of the R and R2 combination to meet the exact output voltage setting by restricting R1 resistance range such that 50KΩ < R1 < 100KΩ for overall system loop stability. Setting Output Voltages R [(Vout /0.80V) -] R2= |
|
|
Link URL |
| Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Contact us | Privacy Policy | Link to Datasheet | 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 |
English ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
