Electronic Components Datasheet Search |
|
TPS40140RHHR Datasheet(PDF) 41 Page - Texas Instruments |
|
|
TPS40140RHHR Datasheet(HTML) 41 Page - Texas Instruments |
41 / 68 page ( ) ( ) ( ) IN RIPPLE CinESR CIN OUT RIPPLE IN OUT V V ESR 1 I I V V 2 ´ = + ´ - ( ) ( ) OUT IN OUT OUT IN(min) 2 sw IN RIPPLE CIN I V V V C V f V ´ - ´ = ´ ´ æ ö ç ÷ è ø RIPPLE RIPPLE(TotOUT) RIPPLE(TotOUT) RIPPLE(COUT) OUT SW Co RIPPLE RIPPLE I V - V - V 8×C × f ESR = = I I 2 TRAN(MAX) OUT OUT OVER I L C (MIN) 2 V V ´ = ´ ´ ( ) 2 TRAN(MAX) OUT IN(min) OUT UNDER I L C (MIN) 2 V V V ´ = ´ - ´ V - V V 1 IN(max) OUT OUT L = × × I V f RIPPLE IN(max) SW TPS40140 www.ti.com SLUS660I – SEPTEMBER 2005 – REVISED JANUARY 2015 9.2.1.2 Detailed Design Procedure 9.2.1.2.1 Step 1: Inductor Selection The inductor is determined by the desired ripple current. The required inductor is calculated by: (21) Typically the peak-to-peak inductor current, IRIPPLE is selected to be around 20% of the rated output current. In this design, IRIPPLE is targeted at 15% of IOUT1. The calculated inductor is 0.89 μH and in practical a 1-μH, 32-A, 1.7 m Ω inductor IHLP-5050FD from Vishay is selected. So, the inductor ripple current is 2.66 A. 9.2.1.2.2 Step 2: Output Capacitor Selection The output capacitor is typically selected by the output load transient response requirement. Equation 22 estimates the minimum capacitor to reach the undervoltage requirement with load step up. Equation 23 estimates the minimum capacitor for overvoltage requirement with load step down. When VIN(min) < 2 ×VOUT, the minimum output capacitance can be calculated using Equation 22. Otherwise, Equation 23 is used. (22) when VIN(min) < 2 × VOUT (23) when VIN(min) > 2×VOUT In this design, VIN(min) is much larger than 2 × VOUT, so Equation 23 is used to determine the minimum capacitance. Based on a 10-A load transient with a maximum of 80-mV deviation, a minimum 417- μF output capacitor is required. In the design, four 220- μF, 4-V, SP capacitor are selected to meet this requirement. Each capacitor has an ESR of 5 m Ω. Another criterion for capacitor selection is the output ripple voltage. The output ripple is determined mainly by the capacitance and the ESR. (24) With 880- μF output capacitance, the ripple voltage at the capacitor is calculated to be 0.76 mV. In the specification, the output ripple voltage should be less than 30 mV, so based on Equation 24, the required maximum ESR is 11 m Ω. The selected capacitors can meet this requirement. 9.2.1.2.3 Step 3: Input Capacitor Selection The input voltage ripple depends on the input capacitance and the ESR. The minimum capacitor and the maximum ESR can be estimated by: (25) (26) For this design, assume VRIPPLE(CIN) is 100 mV and VRIPPLE(CinESR) is 50 mV, so the calculated minimum capacitance is 43.6 μF and the maximum ESR is 2.7 mΩ. Choosing four 22-μF, 16-V, 2-mΩ ESR ceramic capacitors meets this requirement. Copyright © 2005–2015, Texas Instruments Incorporated Submit Documentation Feedback 41 Product Folder Links: TPS40140 |
Similar Part No. - TPS40140RHHR |
|
Similar Description - TPS40140RHHR |
|
|
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 |