Electronic Components Datasheet Search |
|
MP8718 Datasheet(PDF) 14 Page - Monolithic Power Systems |
|
MP8718 Datasheet(HTML) 14 Page - Monolithic Power Systems |
14 / 17 page MP8718 – SYNCHRONOUS STEP-DOWN CONVERTER WITH INTERNAL MOSFETS MP8718 Rev. 0.9 www.MonolithicPower.com 14 2/9/2010 MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2010 MPS. All Rights Reserved. Selecting the Output Capacitor The output capacitor (C2) is required to maintain the DC output voltage. Ceramic, tantalum, or low ESR electrolytic capacitors are recommended. Low ESR capacitors are preferred to keep the output voltage ripple low. The output voltage ripple can be estimated by: ⎟⎟ ⎠ ⎞ ⎜⎜ ⎝ ⎛ × × + × ⎟⎟ ⎠ ⎞ ⎜⎜ ⎝ ⎛ − × × = ∆ 2 C f 8 1 R V V 1 L f V V S ESR IN OUT S OUT OUT Where L is the inductor value and RESR is the equivalent series resistance (ESR) value of the output capacitor. In the case of ceramic capacitors, the impedance at the switching frequency is dominated by the capacitance. The output voltage ripple is mainly caused by the capacitance. For simplification, the output voltage ripple can be estimated by: ⎟⎟ ⎠ ⎞ ⎜⎜ ⎝ ⎛ − × × × × = IN OUT 2 S OUT OUT V V 1 2 C L f 8 V ∆V In the case of tantalum or electrolytic capacitors, the ESR dominates the impedance at the switching frequency. For simplification, the output ripple can be approximated to: ESR IN OUT S OUT OUT R V V 1 L f V ∆V × ⎟⎟ ⎠ ⎞ ⎜⎜ ⎝ ⎛ − × × = The characteristics of the output capacitor also affect the stability of the regulation system. The MP8718 can be optimized for a wide range of capacitance and ESR values. PCB Layout PCB layout is very important to achieve stable operation. Please follow these guidelines and take Figure 4 for references. 1) Keep the connection of input ground and GND pin as short and wide as possible. 2) Keep the connection of input capacitor and IN pin as short and wide as possible. 3) Ensure all feedback connections are short and direct. Place the feedback resistors and compensation components as close to the chip as possible. 4) Route SW away from sensitive analog areas such as FB. 5) Connect IN, SW, and especially GND respectively to a large copper area to cool the chip to improve thermal performance and long-term reliability. 6) Adding RC snubber circuit from IN pin to SW pin can reduce SW spikes. Top Layer Bottom Layer Figure 4—PCB Layout |
Similar Part No. - MP8718 |
|
Similar Description - MP8718 |
|
|
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 |