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SMSC AN 10.8 Rev. 12-16-03 APPLICATION NOTE Application Note 10.8 USB97C223 and USB97C243 Capacitor Selection for Internal Regulator Output Pins
USB97C223 and USB97C243 Capacitor Selection for Internal Regulator Output Pins SMSC AN 10.8 Page 2 Rev. 12-16-03 APPLICATION NOTE
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Hauppauge, NY 11788 (631) 435-6000 FAX (631) 273-3123 Copyright © SMSC 2004. All rights reserved. Circuit diagrams and other information rela ting to SMSC products are included as a m eans of illustrating typical applications. Consequently, complete information sufficient for construction purposes is not necessarily given. Although the information has been checked and is believed to be accurate, no responsibility is assumed for inaccuracies. SMSC reserves the right to make changes to specifications and product descriptions at any time without notice. Contact your local SMSC sales office to obtain the latest specifications before placing your product order. The provision of this information does not convey to the purchaser of the described semiconductor devic es any licenses under any patent ri ghts or other intellectual property rights of SMSC or others. All sales are expressly conditional on your agreement to the terms and conditions of the most recently dated version of SMSC's standard Terms of Sale Agreement dated before the date of your order (t he "Terms of Sale Agreement"). The product may contain design def ects or errors known as anomalies which may caus e the product's functions to deviate from publis hed specifications. Anomaly sheets are availab le upon request. SMSC products are not designed, intended, authorized or warranted for use in any life support or other application where produc t failure could cause or contribute to personal injury or severe property damage. Any and all such uses without prior written approval of an Officer of SMSC and further testing and/or modification will be fully at t he risk of the customer. Copies of this do cument or other SMSC literature, as wel l as the Terms of Sale Agreement, may be obtained by visiting SMSC’s website at http://www .smsc.com. SMSC is a registered trademark of Standard Micros ystems Corporation (“SMSC”). Product names and company names are the trademarks of their respective holders. SMSC DISCLAIMS AND EXCLUDES ANY AND ALL WARRANTIES, INCLUDING WITHOUT LIMITATION ANY AND ALL IMPLIED WARRANTIES OF MERCHANTABILITY, FITN ESS FOR A PARTICULAR PURPOSE, TITLE, AND AGAINST INFRINGEMENT AND THE LIKE, AND ANY AND ALL WARRANTIES ARISING FROM ANY COURSE OF DEALING OR USAGE OF TRADE. IN NO EVENT SHALL SMSC BE LIABLE FOR AN Y DIRECT, INCIDENTAL, INDIRECT, SPECIAL, PUNITIVE, OR CONSEQUENTIAL DAMAGES; OR FOR LOST DATA, PROFITS, SAVINGS OR REVENUES OF ANY KIND; REGARDLESS OF TH E FORM OF ACTION, WHETHER BASED ON CONTRACT; TORT; NEGLIGENCE OF SMSC OR OTHERS; STRICT LI ABILITY; BREACH OF WARRANTY; OR OTHERWISE; WHETHER OR NOT ANY REMEDY OF BUYER IS HELD TO HAVE FAILED OF ITS ESSENTIAL PURPOSE, AND WHET HER OR NOT SMSC HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
USB97C223 and USB97C243 Capacitor Selection for Internal Regulator Output Pins SMSC AN 10.8 Page 3 Rev. 12-16-03 APPLICATION NOTE Overview The USB97C223 and USB97C243 have two internal 1.8V regulators used to provide the digital and analog 1.8V supplies. The output pins of the regulator have very sp ecific capacitor requirements that are described below. It is important that the customer designs their product with the specifications set forth in this document. Requirements Table 1 lists the capacitor requirements on the regulator output pins. Table 1 – Regulator Output Pins USB97C223 PIN NUMBER PIN NAME PIN DESCRIPTION CAPACITOR REQUIREMENT
98 VDDP Analog Regulator
10uF +/- 20 % with < 0.65 Ohm ESR
91 VDDCORE Digital Regulator
10uF +/- 20 % with < 0.65 Ohm ESR USB97C243
50 VDDP Analog Regulator
10uF +/- 20 % with < 0.65 Ohm ESR
43 VDDCORE (closest
to VREG) Digital Regulator Output 10uF +/- 20 % with < 0.65 Ohm ESR Figure 1 and Figure 2 show an example of the degradat ion in performance of the USB97C223 and USB97C243 as the ESR of the capacitor on the output of the regulators is increased to 0.65 Ohm. Figure 1 - 10uF Capacitor with 0.1 Ohm ESR Figure 2 - 10uF Capacitor with 0.65 Ohm ESR
USB97C223 and USB97C243 Capacitor Selection for Internal Regulator Output Pins SMSC AN 10.8 Page 4 Rev. 12-16-03 APPLICATION NOTE SMSC recommends the use of ceramic 10uF capacitors to meet the low ESR requ irements of the regulator output pins of the USB97C223. Ceramic capacitors typically have an ESR of < 0.1 Ohm. Recommended Capacitors, or equivalent: Kemet C0805C106K9PACTU (0805 Package) Kemet C1206C106K9PACTU (1206 Package) Panasonic ECJ-2FF0J106Z (0805 Package) Panasonic ECJ-2FF1A106Z (0805 Package) Tantalum capacitors that have low ESR specifications can also be used, but typically have an ESR closer to 0.5 Ohm.