 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
SPX2945T3-3.3 Datasheet(PDF) 4 Page - Sipex Corporation |
|
||||||||||||||||||||||||||||||
SPX2945T3-3.3 Datasheet(HTML) 4 Page - Sipex Corporation |
|
|
4 / 11 page  4 Rev. B Date:01/20/04 SPX2945 400mA Low Dropout Voltage Regulator with Shutdown ©Copyright 2004 Sipex Corporation SPX2945 - 5.0V BLOCK DIAGRAM FEEDBACK INPUT OUTPUT UNREGULATED DC SHUTDOWN GROUND ERROR ______ 5V TAP SENSE 5V at 400mA MAX TO CMOS OR TTL REFERENCE ERROR DETECTION COMPARATOR ERROR AMPLIFIER 1.23V FROM CMOS OR TTL + + + + + + 60 mV 3 7 8 1 2 6 5 4 . 60kΩ 330kΩ 180kΩ . . 1µF _ _ External Capacitors The stability of the SPX2945 requires a 2.2 µF or greater capacitor between output and ground. Oscillation could occur without this capacitor. Most types of tantalum or aluminum electrolytic works fine here. For operations of below -25 °C solid tantalum is recommended since the many aluminum types have electrolytes that freeze at about -30 °C. The ESR of about 5Ω or less and resonant frequency above 500kHz are the most important parameters in the value of the capaci- tor. The capacitor value can be increased with- out limit. At lower values of output current, less output capacitance is required for stability. For the currents below 10mA the value of the capacitor can be reduced to 0.5 µF and 0.15µF for 1mA. More output capacitance needed for the 8-pin version at voltages below 5V since it runs the error amplifier at lower gain. At worst case 4.7 µF or greater must be used for the condition of 250mA load at 1.23V output. The SPX2945, unlike other low dropout regu- lators will remain stable and in regulation with no load in addition to the internal voltage di- vider. This feature is especially important in applications like CMOS RAM keep-alive. If there is more than 10 inches of wire between the input and the AC filter capacitor, or if a battery is used as the input, then a 0.1 µF tanta- lum or aluminum electrolytic capacitor should be placed from the input to the ground. Instability can occur if there is stray capaci- tance to the SPX2945 feedback terminal (pin 7). This could cause more problems when using a higher value of external resistors to set the output voltage. This problem can be fixed by adding a 100pF capacitor between output and feedback and increasing the output capacitor to at least 3.3 µF. APPLICATION INFORMATION |
Similar Part No. - SPX2945T3-3.3 |
|
Similar Description - SPX2945T3-3.3 |
|
|
|
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
