Electronic Components Datasheet Search |
|
LM2681M6X Datasheet(PDF) 6 Page - National Semiconductor (TI) |
|
|
LM2681M6X Datasheet(HTML) 6 Page - National Semiconductor (TI) |
6 / 8 page Application Information (Continued) Capacitor Selection As discussed in the Positive Voltage Doubler section, the output resistance and ripple voltage are dependent on the capacitance and ESR values of the external capacitors. The output voltage drop is the load current times the output resis- tance, and the power efficiency is Where I Q(V+) is the quiescent power loss of the IC device, and I L 2R out is the conversion loss associated with the switch on-resistance, the two external capacitors and their ESRs. The selection of capacitors is based on the specifications of the dropout voltage (which equals I out Rout), the output volt- age ripple, and the converter efficiency. Low ESR capacitors (Table 1) are recommended to maximize efficiency, reduce the output voltage drop and voltage ripple. Low ESR Capacitor Manufacturers Manufacturer Phone Capacitor Type Nichicon Corp. (708)-843-7500 PL & PF series, through-hole aluminum electrolytic AVX Corp. (803)-448-9411 TPS series, surface-mount tantalum Sprague (207)-324-4140 593D, 594D, 595D series, surface-mount tantalum Sanyo (619)-661-6835 OS-CON series, through-hole aluminum electrolytic Murata (800)-831-9172 Ceramic chip capacitors Taiyo Yuden (800)-348-2496 Ceramic chip capacitors Tokin (408)-432-8020 Ceramic chip capacitors Other Applications Paralleling Devices Any number of LM2681s can be paralleled to reduce the out- put resistance. Each device must have its own pumping ca- pacitor C 1, while only one output capacitor Cout is needed as shown in Figure 3. The composite output resistance is: Cascading Devices Cascading the LM2681s is an easy way to produce a greater voltage (A two-stage cascade circuit is shown in Figure 4). The effective output resistance is equal to the weighted sum of each individual device: R out = 1.5Rout_1 +Rout_2 Note that, the increasing of the number of cascading stages is pracitically limited since it significantly reduces the effi- ciency, increases the output resistnace and output voltage ripple. DS100965-19 FIGURE 3. Lowering Output Resistance by Paralleling Devices www.national.com 6 |
Similar Part No. - LM2681M6X |
|
Similar Description - LM2681M6X |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.NET |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | 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 |