Electronic Components Datasheet Search |
|
A4447SLJTR-T Datasheet(PDF) 8 Page - Allegro MicroSystems |
|
A4447SLJTR-T Datasheet(HTML) 8 Page - Allegro MicroSystems |
8 / 9 page High Voltage Step Down Regulator A4447 8 Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com R1 R2 D1 RTSET COUT CIN1 CIN2 L1 U1 VIN VOUT CBOOT CBYP GND GND GND GND Recommended PCB Layout The large star ground area on the populated side of the PCB, shown in the diagram as the GND nodes, supports high current throughput, and allows the VOUT node to be located as close as practical to the A4447 (U1). Thermal conduction from the A4447 is enhanced by direct contact of its exposed thermal pad to the smaller ground area under the A4447. This area is connected by thermal vias to the large copper ground plane on the unpopulated side of the PCB. Star Ground Exposed copper thermal ground area on the unpopulated side of the PCB In order to minimize the effects of ground bounce and offset issues, it is important to have a low impedance ground located very close to the device. This grounding scheme is known as star grounding. It is likely that a ground plane will be necessary to meet thermal requirements. The recommended land pattern illus- trates how to create a low impedance ground that will also assist with removing thermal energy from the device. The input capacitor must be placed as close as possible to the VIN terminal because during the on cycle it is responsible for supplying the current to the switcher. During the off cycle, the current path is from the negative terminal of the COUT cap, through the diode and inductor, and then to the load. As a result, COUT and the rectifier diode must share the connection at the negative terminal of the CIN capacitor in order to reduce ground bounce when the diode is conducting. The inductor should be connected as close as possible to the switching node to minimize noise. Some applications may require a shielded inductor due to EMI restrictions. This will depend on the application and parameters defined by the system that will host the regulator. The high voltage-switching node could affect RTSET. If longer off-times are used, the resistance on the RTSET pin can be quite large. When designing the layout, try to keep RTSET away from the inductor and switching node. It is also beneficial to keep the trace as short as possible to reduce the effect of noise injection. Because of this layout guideline, the TSET pin is located on the other side of the device, away from the switching node. The FB resistor network should have a lower impedance to avoid interference from the switching node. Because the impedance on the FB node can be controlled, it is not as critical to keep the network isolated. It is important to keep the ground trace short so that ground bounce cannot effect the output voltage regulation. VOUT VIN R2 R1 L1 COUT CIN1 CIN2 CBYP D1 RTSET CBOOT 1 A4447 ENB LX VBIAS VIN GND FB TSET BOOT PAD |
Similar Part No. - A4447SLJTR-T |
|
Similar Description - A4447SLJTR-T |
|
|
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 |