Electronic Components Datasheet Search |
|
LP2985-20YZQR Datasheet(PDF) 10 Page - Texas Instruments |
|
LP2985-20YZQR Datasheet(HTML) 10 Page - Texas Instruments |
10 / 15 page LP2985LV 150mA LOW NOISE, LOW DROPOUT REGULATOR WITH SHUTDOWN FOR OUTPUT VOLTAGES <2.3 V SLVS552 − OCTOBER 2004 10 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 APPLICATION INFORMATION output capacitor (COUT) (continued) It is critical that both the minimum capacitance and ESR requirement be met over the entire operating temperature range. Depending on the type of capacitors used, both these parameters can vary significantly with temperature (see Capacitor Characteristics section). noise bypass capacitor (CBYPASS) The LP2985LV allows for low noise performance with the use of a bypass capacitor that is connected to the internal band-gap reference via the BYPASS pin. This high-impedance band-gap circuitry is biased in the microampere range and, thus, cannot be loaded significantly, else its output − and correspondingly the output of the regulator − will change. Thus, for best output accuracy, dc leakage current through CBYPASS should be minimized as much as possible and should never exceed 100 nA. A 10-nF capacitor is recommended for CBYPASS; ceramic and film capacitors are well suited for this purpose. capacitor characteristics ceramic Ceramic capacitors are ideal choices for use on the output of the LP2985LV for several reasons. For capacitances in the range of 2.2 µF to 4.7 µF, ceramic capacitors have the lowest cost and the lowest ESR, making them choice candidates for filtering high-frequency noise. For instance, a typical 2.2- µF ceramic capacitor has an ESR in the range of 10 m Ω to 20mΩ and satisfies minimum ESR requirements of the regulator. Ceramic capacitors have one glaring disadvantage that must be taken into account − a poor temperature coefficient, where the capacitance can vary significantly with temperature. For instance, a large-value ceramic capacitor ( ≥2.2 µF) can lose more than half of its capacitance as temperature rises from 25°C to 85°C. Thus, a 2.2 µF at 25°C will drop well below the minimum COUT required for stability as ambient temperature rises. For this reason, select an output capacitor that maintains the minimum 2.2 µF required for stability over the entire operating temperature range. Note that there are some ceramic capacitors that can maintain a ±15% capacitance tolerance over temperature. tantalum Tantalum capacitors can be used at the output of the LP2985LV, but there are significant disadvantages that could prohibit their use. • In the 1-µF to 4.7-µF range, tantalum capacitors are more expensive than ceramics of the equivalent capacitance and voltage ratings. • Tantalum capacitors have higher ESRs than their equivalent-sized ceramic counterparts. Thus, to meet the ESR requirements, a higher-capacitance tantalum may be required, at the expense of larger size and higher cost. • The ESR of a tantalum capacitor increases as temperature drops, as much as double from 25°C to −40 °C. Thus, ESR margins must be maintained over the temperature range in order to prevent regulator instability. |
Similar Part No. - LP2985-20YZQR |
|
Similar Description - LP2985-20YZQR |
|
|
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 |