Electronic Components Datasheet Search |
|
NCP1117ST33T3 Datasheet(PDF) 9 Page - ON Semiconductor |
|
NCP1117ST33T3 Datasheet(HTML) 9 Page - ON Semiconductor |
9 / 16 page NCP1117, NCV1117 http://onsemi.com 9 Protection Diodes The NCP1117 family has two internal low impedance diode paths that normally do not require protection when used in the typical regulator applications. The first path connects between Vout and Vin, and it can withstand a peak surge current of about 15 A. Normal cycling of Vin cannot generate a current surge of this magnitude. Only when Vin is shorted or crowbarred to ground and Cout is greater than 50 mF, it becomes possible for device damage to occur. Under these conditions, diode D1 is required to protect the device. The second path connects between Cadj and Vout, and it can withstand a peak surge current of about 150 mA. Protection diode D2 is required if the output is shorted or crowbarred to ground and Cadj is greater than 1.0 mF. Figure 22. Protection Diode Placement 1 2 Output 3 Input NCP1117 XTA ++ Cout Cin R2 + Cadj R1 1N4001 D1 D2 1N4001 A combination of protection diodes D1 and D2 may be required in the event that Vin is shorted to ground and Cadj is greater than 50 mF. The peak current capability stated for the internal diodes are for a time of 100 ms with a junction temperature of 25 °C. These values may vary and are to be used as a general guide. Load Regulation The NCP1117 series is capable of providing excellent load regulation; but since these are three terminal devices, only partial remote load sensing is possible. There are two conditions that must be met to achieve the maximum available load regulation performance. The first is that the top side of programming resistor R1 should be connected as close to the regulator case as practicable. This will minimize the voltage drop caused by wiring resistance RW + from appearing in series with reference voltage that is across R1. The second condition is that the ground end of R2 should be connected directly to the load. This allows true Kelvin sensing where the regulator compensates for the voltage drop caused by wiring resistance RW −. Figure 23. Load Sensing 1 2 Output 3 Input NCP1117 XTA + + Cout Cin R1 Remote Load RW+ RW− R2 Thermal Considerations This series contains an internal thermal limiting circuit that is designed to protect the regulator in the event that the maximum junction temperature is exceeded. When activated, typically at 175 °C, the regulator output switches off and then back on as the die cools. As a result, if the device is continuously operated in an overheated condition, the output will appear to be oscillating. This feature provides protection from a catastrophic device failure due to accidental overheating. It is not intended to be used as a substitute for proper heatsinking. The maximum device power dissipation can be calculated by: PD + TJ(max) * TA R qJA The devices are available in surface mount SOT−223 and DPAK packages. Each package has an exposed metal tab that is specifically designed to reduce the junction to air thermal resistance, RqJA, by utilizing the printed circuit board copper as a heat dissipater. Figures 18 and 19 show typical RqJA values that can be obtained from a square pattern using economical single sided 2.0 ounce copper board material. The final product thermal limits should be tested and quantified in order to insure acceptable performance and reliability. The actual RqJA can vary considerably from the graphs shown. This will be due to any changes made in the copper aspect ratio of the final layout, adjacent heat sources, and air flow. |
Similar Part No. - NCP1117ST33T3 |
|
Similar Description - NCP1117ST33T3 |
|
|
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 |