Electronic Components Datasheet Search |
|
ADP3031ARM Datasheet(PDF) 6 Page - Analog Devices |
|
ADP3031ARM Datasheet(HTML) 6 Page - Analog Devices |
6 / 8 page ADP3031 REV. PrB –6– PRELIMINARY TECHNICAL DATA Capacitor Selection The ADP3031 requires an input capacitor to reduce the switching ripple and noise on the IN pin. The value of the input capacitor will be dependent on the application. For most applications, a minimum of 10 µF is required. For applications that are running close to current limit or that have large transient loads, input capacitors in the range of 22 µF to 47 µF are required. The selection of the output capacitor is also dependent on the application. Given the allowable output ripple voltage, ∆V OUT, the criteria for selecting the output capacitor can be calculated using the following equations: () OUT IN OUT OUT sOUT OUT VV CI fV V 8 − ≥× ×× ∆ (4) () OUT OUT C L V ESR IPEAK ∆ ≤ (5) When selecting an output capacitor, make sure that the ripple current rating is sufficient to cover the rms switching current of the ADP3031. The ripple current in the output capacitor is given by the following: () OUT IN RMS OUT OUT IN VV IC I V − = (6) Multi-layer ceramic capacitors are a good choice, as they have low ESR, high ripple current rating and a very small package size. Tantalum or OS-CON capacitors can be used, however they have a larger package size and have higher ESR. Table 2 shows a list of several capacitor manufactur- ers. Consult the manufacturer for more information. Table 2. Capacitor Manufacturers Vendor Phone # Web Address AVX 408-573-4150 www.avxcorp.com Murata 714-852-2001 www.murata.com Sanyo 408-749-9714 www.sanyovideo.com Taiyo-Yuden 408-573-4150 www.t-yuden.com Diode Selection In specifying a diode, consideration must be given to speed, the forward current, the forward voltage drop, reverse leakage current, and the breakdown voltage. The output diode should be rated to handle the maximum output current. If the output can be subjected to accidental short circuits then the diode must be rated to handle currents up to the current limit of the ADP3031. The breakdown rating of the diode must exceed the output voltage. A high-speed diode with low forward drop, and low leakage will help improve the efficiency of the converter by lowering the losses of the diode. Schottky diodes are recommended. Loop Compensation Like most current programmed PWM converters, the ADP3031 needs compensation to maintain stability over the operating conditions of the particular application. For operation at duty cycles above 50%, the choice of inductor is critical in maintaining stability. If the slope of the inductor current is too small or too large, the circuit will be unstable. See Inductor Selection for more information on choosing the proper inductor. The ADP3031 provides a pin (COMP) for compensating the voltage feedback loop. This is done by connecting a series RC network from the COMP pin to GND. See Figure 2. For most applications, the compensation resistor, R C, should be in the range of 30 kΩ < RC < 300 kΩ and the compensation capacitor, C C , in the range of 100 pF < C C < 4 nF. REF COMP FB C2 CC RC gm ERROR AMP Figure 2. Compensation Components Shutdown The ADP3031 shuts down to reduce the supply current to 1 µA maximum when the shutdown pin is pulled low. In this mode, the internal reference, error amplifier, comparator, biasing circuitry, and the internal MOSFET switch are turned off. Note that the output is still connected to the input via the inductor and Schottky diode when in shut- down. Layout Procedure In order to get high efficiency, good regulation and stability, a good printed circuit board layout is required. It is strongly recommended that the evaluation board layout be followed as closely as possible. Use the following general guidelines when designing printed circuit boards (refer to Figure 1): 1. Keep C IN close to the IN pin of the ADP3031. 2. Keep the high current path from C IN, through L1, to the SW pin and PGND pin as short as possible. 3. Similarly, keep the high current path from C IN, through L1, D1, and C OUT as short as possible. 4. High current traces should be kept as short and as wide as possible. 5. Place the compensation components as close to the COMP pin as possible. 6. Place the feedback resistors as close to the FB pin as possible to prevent noise pickup. 7. Avoid routing noise sensitive traces near the high current traces and components. |
Similar Part No. - ADP3031ARM |
|
Similar Description - ADP3031ARM |
|
|
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 |