 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
LM2696MXA Datasheet(PDF) 10 Page - National Semiconductor (TI) |
|
|
||||||||||||||||||||||||||||||
LM2696MXA Datasheet(HTML) 10 Page - National Semiconductor (TI) |
|
|
10 / 19 page  Application Information (Continued) It can be seen that the average output voltage is higher than the gained up reference by exactly half the output voltage ripple. The output voltage may then be appended according to the voltage ripple. The appended V OUT term may be expressed using the relationship: One should note that for high output voltages (>5V), a load of approximately 15 mA may be required for the output voltage to reach the desired value. INPUT CAPACITOR Because PV IN is the power rail from which the output voltage is derived, the input capacitor is typically selected according to the load current. In general, package size and ESR de- termine the current capacity of a capacitor. If these criteria are met, there should be enough capacitance to prevent impedance interactions with the source. In general, it is recommended to use a low ESR, high capacitance electro- lytic and ceramic capacitor in parallel. Using two capacitors in parallel ensures adequate capacitance and low ESR over the operating range. The Sanyo MV-WX series electrolytic capacitors and a ceramic capacitor with X5R or X7R dielec- tric are an excellent combination. To calculate the input capacitor RMS, one may use the following relationship: that can be approximated by, Typical values are 470 µF for the electrolytic capacitor and 0.1 µF for the ceramic capacitor. AV IN CAPACITOR AV IN is the analog bias rail of the device. It should be bypassed externally with a small (1 µF) ceramic capacitor to prevent unwanted noise from entering the device. In a shut- down state the current needed by AV IN will drop to approxi- mately 12 µA, providing a low power sleep state. In most cases of operation, AV IN is connected to PVIN; however, it is possible to have split rail operation where AV IN is at a higher voltage than PV IN.AVIN should never be lower than PV IN. Splitting the rails allows the power conversion to occur from a lower rail than the AV IN operating range. SOFT-START CAPACITOR The SS capacitor is used to slowly ramp the reference from 0V to its final value of 1.25V (during shutdown this pin will be discharged to 0V). This controlled startup ability eliminates large in-rush currents in an attempt to charge up the output capacitor. By changing the value of this capacitor, the dura- tion of the startup may be changed accordingly. The startup time may be calculated using the following relationship: Where I SS is the soft-start pin source current (1 µA typical) that may be found in the electrical characteristics table. While the C SS capacitor can be sized to meet the startup requirements, there are limitations to its size. If the capacitor is too small, the soft-start will have little effect as the refer- ence voltage is rising faster than the output capacitor can be charged causing the part to go into current limit. Therefore a minimum soft-start time should be taken into account. This can be determined by: 20153431 FIGURE 2. Average and Ripple Output Voltages www.national.com 10 |
Similar Part No. - LM2696MXA |
|
Similar Description - LM2696MXA |
|
|
|
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 |
English ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
