 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
SP6652 Datasheet(PDF) 6 Page - Sipex Corporation |
|
||||||||||||||||||||||||||||||
SP6652 Datasheet(HTML) 6 Page - Sipex Corporation |
|
|
6 / 16 page  6 May25-07 RevH SP6652 1A, High Efficiency, Current Mode PWM Buck Regulator © 2007 Sipex Corporation when the output voltage is low. The inductor current tends to rise until the energy loss from the discharge resistances are equal to the energy gained during the charge phase. For this reason, the clock frequency is cut in half when the feedback pin is below 0.3V, ef- fectively reducing the minimum duty cycle in half.Above V(FB) = 0.3V the clock frequency is normal (see Typical Operating Character- istics: Inductor Current vs. VOUT) Voltage Loop and Compensation in PWM Mode The voltage loop section of the circuit con- sists of the error amplifier and the translator circuits (see functional diagram). The input of the voltage loop is the 0.8V reference volt- age minus the divided down output voltage at the feedback pin. The output of the error amplifier is translated from a ground referred signal (the COMP node) to a power input voltage referred signal. The output of the voltage loop is fed to the positive terminal of the Current Loop comparator, and repre- sents the peak inductor current necessary to close the loop. The total power supply loop is compensated with a series RC network connected from the COMP pin to ground. Compensation is simple due to current-mode control. The modulator has two dominant poles: one at a low frequency, and one above the crossover frequency of the loop, as seen in the graph below, Linearized Modulator Frequency Response vs. Inductor Value. The low frequency pole for L1= 5µH is 4kHz, the second pole is 500kHz, and the gain-bandwidth is 20kHz. The total loop crossoverfrequencyischosentobe200kHz, which is 1/6th of the clock frequency. This sets the second modulator pole at 2.5 times the crossover frequency. Therefore the gain of the error amplifier can be 200kHz/20kHz = 10 at the first modulator pole of 4kHz. The error amp transconductance is 1mA/V, so this sets the RZ resistor value in the com- pensation network at 10/1mA/V = 10kΩ. The zero frequency is placed at the first pole to provide at total system response of -20dB/decade (the zero from the error amp cancels the first modulator pole, leaving the L1VAL 2u 3u 4u 5u 6u 7u 8u 9u 10u Mod_pole1 Mod_pole2 Gbw_modfb 0 4K 8K 12K 16K 20K 1 0 0.4M 0.8M 1.2M 1.6M 2.0M 2 0 10K 20K 30K 40K 50K 3 >> 1 2 3 Conditions: VIN=5V, VOUT=3.3V, fCLK=1.4MHz, COUT=10µF, and MCV=132mV/µs. The inductor is varied from 2µH to 10µH Linearized Modulator Frequency Response vs. Inductor DetaileD Description |
Similar Part No. - SP6652 |
|
Similar Description - SP6652 |
|
|
|
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 |
English ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
