 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
LTC1627 Datasheet(PDF) 11 Page - Linear Technology |
|
||||||||||||||||||||||||||||||
LTC1627 Datasheet(HTML) 11 Page - Linear Technology |
|
|
11 / 16 page  11 LTC1627 Checking Transient Response The regulator loop response can be checked by looking at the load transient response. Switching regulators take several cycles to respond to a step in load current. When a load step occurs, VOUT immediately shifts by an amount equal to ( ∆ILOAD • ESR), where ESR is the effective series resistance of COUT. ∆ILOAD also begins to charge or dis- charge COUT, which generates a feedback error signal. The regulator loop then acts to return VOUT to its steady-state value. During this recovery time VOUT can be monitored for overshoot or ringing that would indicate a stability prob- lem. The internal compensation provides adequate com- pensation for most applications. But if additional compen- sation is required, the ITH pin can be used for external compensation as shown in Figure 7. A second, more severe transient is caused by switching in loads with large (>1 µF) supply bypass capacitors. The discharged bypass capacitors are effectively put in parallel with COUT, causing a rapid drop in VOUT. No regulator can deliver enough current to prevent this problem if the load switch resistance is low and it is driven quickly. The only solution is to limit the rise time of the switch drive so that APPLICATIONS INFORMATION the load rise time is limited to approximately (25 • CLOAD). Thus, a 10 µF capacitor would require a 250µs rise time, limiting the charging current to about 130mA. PC Board Layout Checklist When laying out the printed circuit board, the following checklist should be used to ensure proper operation of the LTC1627. These items are also illustrated graphically in the layout diagram of Figure 7. Check the following in your layout: 1. Are the signal and power grounds segregated? The LTC1627 signal ground consists of the resistive divider, the optional compensation network (RC and CC1), CSS and CC2. The power ground consists of the (–) plate of CIN, the (–) plate of COUT and Pin 4 of the LTC1627. The power ground traces should be kept short, direct and wide. The signal ground and power ground should converge to a common node in a star- ground configuration. 2. Does the VFB pin connect directly to the feedback resistors? The resistive divider R1/R2 must be con- nected between the (+) plate of COUT and signal ground. Figure 7. LTC1627 Layout Diagram CC2 CC1 RC OPTIONAL OPTIONAL CSS COUT CIN D1 D2 CV CB L1 R2 R1 BOLD LINES INDICATE HIGH CURRENT PATHS 1 2 3 4 8 7 6 5 SYNC/FCB VDR VIN SW ITH RUN/SS VFB GND LTC1627 VIN 1627 F07 + – VOUT + – + + |
Similar Part No. - LTC1627 |
|
Similar Description - LTC1627 |
|
|
|
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
