LM2737 Reference Design - Synchronous Buck Controller, High Current Output: 10-13.2V Input; 2.5V @ 5A Output

  Design Specifications

Inputs Outputs #1
VinMin=4.5 Vout1=1
VinMax=5.5 Iout1=20
   Design Resources

LM2737 Reference Design

  Additional Resources


LM2737 Product Folder
   Bill Of Materials

Part Manufacturer Part# Attributes
C10 TDK C3216X5R0J106M 10u F
C11 TDK C3216X5R0J106M 10u F
C13 Sanyo 6MV2200WG 2200u F
C14 Sanyo 6MV2200WG 2200u F
C17 Sanyo 6MV2200WG 2200u F
C18 Sanyo 6MV2200WG 2200u F, 0.066 Ohms
C19 Sanyo 6MV2200WG 2200u F, 0.066 Ohms
C2 Vishay VJ0805Y104KXXAT 0.1u F
C20 Sanyo 6MV2200WG 2200u F
C22 Sanyo 6MV2200WG 2200u F
C23 Sanyo 6MV2200WG 2200u F
C3 Vishay VJ0805Y562KXXAT 5.6n F
C4 Vishay VJ0805A680KXXAT 68p F
C5 Vishay VJ0805Y273KXXAT 27n F
C6 Vishay VJ0805Y104KXXAT 0.1u F
C8 Vishay C2012X5R1C105K 1u F
C9 TDK C3216X5R0J106M 10u F
D1 ONSEMI MBR0520LT1 0.385 V
L1 Coilcraft SER1590-681 0.68u H, 0.001 Ohms
L2 Coilcraft DO1813P-561HC 0.56u H, 0.01 Ohms
M1 Siliconix SI4866DY
M2 Siliconix SI4866DY
M3 Siliconix SI4866DY
M4 Siliconix SI4866DY
R1 Vishay CRCW080510R0JRT6 10 Ohms
R11 Vishay CRCW08051002FRT6 10k Ohms
R3 Vishay CRCW08052611FRT6 2.61k Ohms
R4 Vishay CRCW08058252FRT6 82.5k Ohms
R5 Vishay CRCW08057151FRT6 7.15k Ohms
R6 Vishay CRCW08051001FRT6 1k Ohms
Rf1 Vishay CRCW08051001FRT6 1k Ohms
Rf3 Vishay CRCW08051501FRT6 1.5k Ohms
U1 National Semiconductor LM2737

  Design Description

The design uses a LM2737 synchronous controller utilizing external high side and low side N-channel MOSFETs. 200kHz switching frequency has been chosen to maximize efficiency. In such high current applications careful PC board layout is critical to achieve low switching losses and clean, stable operation. The switching power stage requires particular attention. Few points to note for this design are:

1) Decoupling capacitors are close to IC pins as possible. Keep separate power ground plane.

2) Input and output capacitors are connected to the power ground plane; all other capacitors are connected to the signal ground plane.

3) High current paths are very short.

4) Multiple MOSFETs have been used to reduce the conduction and switching losses

5) Feedback connections are short and direct.

6) High-side MOSFETs are as close as possible to the controller



  Schematic

Example Schematic Showing Connection for all Components.


  Layout


NSC0163-PCB