 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
NCP1450ASN27T1 Datasheet(PDF) 18 Page - ON Semiconductor |
|
|
|||||||||||||||||||||||||||||
NCP1450ASN27T1 Datasheet(HTML) 18 Page - ON Semiconductor |
|
|
18 / 22 page  NCP1450A http://onsemi.com 18 APPLICATION CIRCUIT INFORMATION Step−up Converter Design Equations The NCP1450A PWM step−up DC−DC controller is designed to operate in continuous conduction mode and can be defined by the following equations. External components values can be calculated from these equations, however, the optimized value should obtained through experimental results. Calculation Equation D v VOUT ) VD * VIN VOUT ) VD * VS IL IO (1 * D) L (VOUT ) VD * VIN)(1 * D)2 f IO DIR IPK IL (1 ) DIR 2 ) DQ (IL * IO)(1 * D) f VPP [ D Q COUT ) (IL * IO) ESR NOTES: D − On−time duty cycle IL − Average inductor current IPK − Peak inductor current DIR − Delta inductor current to average inductor current ratio IO − Desired dc output current VIN − Nominal operating dc input voltage VOUT − Desired dc output voltage VD − Diode forward voltage VS − Saturation voltage of the external transistor switch DQ − Charge stores in the COUT during charging up ESR − Equivalent series resistance of the output capacitor Design Example It is supposed that a step−up DC−DC controller with 3.3 V output delivering a maximum 1000 mA output current with 100 mV output ripple voltage powering from a 2.4 V input is to be designed. Design parameters: VIN = 2.4 V VOUT = 3.3 V IO = 1.0 A Vpp = 100 mV f = 180 kHZ DIR = 0.2 (typical for small output ripple voltage) Assume the diode forward voltage and the transistor saturation voltage are both 0.3 V. Determine the maximum steady state duty cycle at VIN = 2.4 V: D + 3.3 V ) 0.3V * 2.4V 3.3 V ) 0.3V * 0.3V + 0.364 Calculate the maximum inductance value which can generate the desired current output and the preferred delta inductor current to average inductor current ratio: L v (3.3 V ) 0.3V * 2.4V)(1 * 0.364)2 180000 Hz 1A 0.2 + 13.5mH Determine the average inductor current and peak inductor current: IL + 1 1 * 0.364 + 1.57 A IPK + 1.57A (1 ) 0.2 2 ) + 1.73A Therefore, a 12 mH inductor with saturation current larger than 1.73 A can be selected as the initial trial. Calculate the delta charge stored in the output capacitor during the charging up period in each switching cycle: DQ + (1.57A * 1A)(1 * 0.364) 18000Hz + 2.01mC Determine the output capacitance value for the desired output ripple voltage: Assume the ESR of the output capacitor is 0.15 W, COUT u 2.01 mC 100mV * (1.57A * 1A) 0.15 W + 138.6 mF Therefore, a Tantalum capacitor with value of 150 mF to 220 mF and ESR of 0.15 W can be used as the output capacitor. However, according to experimental result, 220 mF output capacitor gives better overall operational stability and smaller ripple voltage. External Component Selection Inductor Selection The NCP1450A is designed to work well with a 6.8 to 12 mH inductors in most applications 10 mH is a sufficiently low value to allow the use of a small surface mount coil, but large enough to maintain low ripple. Lower inductance values supply higher output current, but also increase the ripple and reduce efficiency. Higher inductor values reduce ripple and improve efficiency, but also limit output current. The inductor should have small DCR, usually less than 1 W, to minimize loss. It is necessary to choose an inductor with a saturation current greater than the peak current which the inductor will encounter in the application. |
Similar Part No. - NCP1450ASN27T1 |
|
Similar Description - NCP1450ASN27T1 |
|
|
|
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
