 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
RT9168-49CS Datasheet(PDF) 7 Page - List of Unclassifed Manufacturers |
|
||||||||||||||||||||||||||||||
RT9168-49CS Datasheet(HTML) 7 Page - List of Unclassifed Manufacturers |
|
|
7 / 13 page  RT9168/A DS9168/A-03 May 2001 www.richtek-ic.com.tw 7 Applications Guides Capacitor Selection and Regulator Stability Like any low-dropout regulator, the external capacitors used with the RT9168/A must be carefully selected for regulator stability and performance. Using a capacitor whose value is > 1 µF on the RT9168/A input and the amount of capacitance can be increased without limit. The input capacitor must be located not more than 0.5" from the input pin of the IC and returned to a clean analog ground. Any good quality ceramic or tantalum can be used for this capacitor. The capacitor with larger value and lower ESR (equivalent series resistance) provides better PSRR and line-transient response. The output capacitor must meet both requirements for minimum amount of capacitance and ESR in all LDO applications. The RT9168/A is designed specifically to work with low ESR ceramic output capacitor in space- saving and performance consideration. Using a ceramic capacitor whose value is at least 1 µF with ESR is > 5m Ω on the RT9168/A output ensures stability. The RT9168/A still works well with output capacitor of other types due to the wide stable ESR range. Fig.1 shows the curves of allowable ESR range as a function of load current for various output voltages and capacitor values. Output capacitor of larger capacitance can reduce noise and improve load-transient response, stability, and PSRR. The output capacitor should be located not more than 0.5" from the VOUT pin of the RT9168/A and returned to a clean analog ground. Note that some ceramic dielectrics exhibit large capacitance and ESR variation with temperature. It may be necessary to use 2.2 µF or more to ensure stability at temperatures below -10°C in this case. Also, tantalum capacitors, 2.2 µF or more may be needed to maintain capacitance and ESR in the stable region for strict application environment. Tantalum capacitors maybe suffer failure due to surge current when it is connected to a low-impedance source of power (like a battery or very large capacitor). If a tantalum capacitor is used at the input, it must be guaranteed to have a surge current rating sufficient for the application by the manufacture. Load-Transient Considerations The RT9168/A load-transient response graphs (see Typical Operating Characteristics) show two components of the output response: a DC shift from the output impedance due to the load current change, and the transient response. The DC shift is quite small due to the excellent load regulation of the IC. Typical output voltage transient spike for a step change in the load current from 0mA to 50mA is tens mV, depending on the ESR of the output capacitor. Increasing the output capacitor’s value and decreasing the ESR attenuates the overshoot. Shutdown Input Operation The RT9168/A is shutdown by pulling the SHDN input low, and turned on by driving the input high. If this feature is not to be used, the SHDN input should be tied to VIN to keep the regulator on at all times (the SHDN input must not be left floating). Fig. 1 COUT = 4.7 µF COUT = 1 µF Region of Stable COUT ESR vs. Load Current 0 40 80 120 160 200 Load Current (mA) 100 0.001 0.01 0.1 1 10 |
Similar Part No. - RT9168-49CS |
|
Similar Description - RT9168-49CS |
|
|
|
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
