 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
TOP257PN Datasheet(PDF) 27 Page - Power Integrations, Inc. |
|
||||||||||||||||||||||||||||||
TOP257PN Datasheet(HTML) 27 Page - Power Integrations, Inc. |
|
|
27 / 49 page  Rev. F 01/09 27 TOP252-262 www.powerint.com Figure 45b. TOPSwitch-HX Full Range EMI Scan (132 kHz With Jitter) With Identical Circuitry and Conditions. -20 -10 0 -10 20 30 40 50 60 70 80 0.15 1 10 30 Frequency (MHz) EN55022B (QP) EN55022B (AV) EN55022B (QP) EN55022B (AV) -20 -10 0 -10 20 30 40 50 60 70 80 0.15 1 10 30 Frequency (MHz) TOPSwitch-HX (with jitter) Figure 45a. Fixed Frequency Operation Without Jitter. Standby Consumption Frequency reduction can significantly reduce power loss at light or no load, especially when a Zener clamp is used. For very low secondary power consumption, use a TL431 regulator for feedback control. A typical TOPSwitch-HX circuit automatically enters MCM mode at no load and the low frequency mode at light load, which results in extremely low losses under no-load or standby conditions. High Power Designs The TOPSwitch-HX family contains parts that can deliver up to 333 W. High power designs need special considerations. Guidance for high power designs can be found in the Design Guide for TOPSwitch-HX (AN-43). TOPSwitch-HX Layout Considerations The TOPSwitch-HX has multiple pins and may operate at high power levels. The following guidelines should be carefully followed. Primary Side Connections Use a single point (Kelvin) connection at the negative terminal of the input filter capacitor for the TOPSwitch-HX SOURCE pin and bias winding return. This improves surge capabilities by returning surge currents from the bias winding directly to the input filter capacitor. The CONTROL pin bypass capacitor should be located as close as possible to the SOURCE and CONTROL pins, and its SOURCE connection trace should not be shared by the main MOSFET switching currents. All SOURCE pin referenced components connected to the MULTI- FUNCTION (M-pin), VOLTAGE MONITOR (V-pin) or EXTERNAL CURRENT LIMIT (X-pin) pins should also be located closely between their respective pin and SOURCE. Once again, the SOURCE connection trace of these components should not be shared by the main MOSFET switching currents. It is very critical that SOURCE pin switching currents are returned to the input capacitor negative terminal through a separate trace that is not shared by the components connected to CONTROL, MULTI-FUNCTION, VOLTAGE MONITOR or EXTERNAL CURRENT LIMIT pins. This is because the SOURCE pin is also the controller ground reference pin. Any traces to the M, V or X pins should be kept as short as possible and away from the DRAIN trace to prevent noise coupling. VOLTAGE MONITOR resistors (R1 and R2 in Figures 46, 47, 48, R3 and R4 in Figure 49, and R14 in Figure 50) should be located close to the M or V pin to minimize the trace length on the M or V pin side. Resistors connected to the M, V or X pin should be connected as close to the bulk cap positive terminal as possible while routing these connections away from the power switching circuitry. In addition to the 47 μF CONTROL pin capacitor, a high frequency bypass capacitor in parallel may be used for better noise immunity. The feedback optocoupler output should also be located close to the CONTROL and SOURCE pins of TOPSwitch-HX. Y-Capacitor The Y-capacitor should be connected close to the secondary output return pin(s) and the positive primary DC input pin of the transformer. Heat Sinking The tab of the Y package (TO-220C) and E package (eSIP-7C) and L package (eSIP-7F) are internally electrically tied to the SOURCE pin. To avoid circulating currents, a heat sink attached to the tab should not be electrically tied to any primary ground/source nodes on the PC board. When using a P (DIP-8), G (SMD-8) or M (DIP-10) package, a copper area underneath the package connected to the SOURCE pins will act as an effective heat sink. On double sided boards, topside and bottom side areas connected with vias can be used to increase the effective heat sinking area. In addition, sufficient copper area should be provided at the anode and cathode leads of the output diode(s) for heat sinking. In Figures 46 to 50 a narrow trace is shown between the output rectifier and output filter capacitor. This trace acts as a thermal relief between the rectifier and filter capacitor to prevent excessive heating of the capacitor. |
Similar Part No. - TOP257PN |
|
Similar Description - TOP257PN |
|
|
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
