LM2678 SIMPLE SWITCHER High Efficiency 3A Step-Down Voltage Regulator
LM2678 特性Features
- Efficiency up to 92%
- Simple and easy to design with (using off-the-shelf external components)
- 120 mΩ DMOS output switch
- 3.3V, 5V and 12V fixed output and adjustable (1.2V to 37V ) versions
- 50μA standby current when switched OFF
- ±2%maximum output tolerance over full line and load conditions
- Wide input voltage range: 8V to 40V
- 260 KHz fixed frequency internal oscillator
- −40 to +125°C operating junction temperature range
LM2678 概述Description
The LM2678 series of regulators are monolithic integrated circuits which provide all of the active functions for a step-down (buck) switching regulator capable of driving up to 5A loads with excellent line and load regulation characteristics. High efficiency (>90%) is obtained through the use of a low ON-resistance DMOS power switch. The series consists of fixed output voltages of 3.3V, 5V and 12V and an adjustable output version.
The SIMPLE SWITCHER concept provides for a complete design using a minimum number of external components. A high fixed frequency oscillator (260KHz) allows the use of physically smaller sized components. A family of standard inductors for use with the LM2678 are available from several manufacturers to greatly simplify the design process.
The LM2678 series also has built in thermal shutdown, current limiting and an ON/OFF control input that can power down the regulator to a low 50μA quiescent current standby condition. The output voltage is guaranteed to a ±2% tolerance. The clock frequency is controlled to within a ±11% tolerance.
LM2678 应用领域Applications
- Simple to design, high efficiency (>90%) step-down switching regulators
- Efficient system pre-regulator for linear voltage regulators
- Battery chargers
LM2678 典型性能Typical Application
| LM2678 典型性能Typical Application | LM2678 功能框图Block Diagram | LM2678 典型性能Typical Performance |
|---|
LM2678 性能参数Parametrics
| Paramaters / Values | LM2678 | LM22678 |
|---|---|---|
| Output Current | 5000 mA | 5000 mA |
| Input Min Voltage | 15, 8 Volt | 4.5 Volt |
| Input Max Voltage | 40 Volt | 42 Volt |
| Output Min | 3.3, 1.23, 12, 5 Volt | 1.285 Volt |
| Output Max | 3.3, 12, 37, 5 Volt | |
| Frequency Min | 260 kHz | |
| Frequency Max | 260 kHz | |
| Efficiency (peak) | 84, 92, 82 % | 92 % |
| On/Off Pin | Yes | Yes |
| PowerGood / Error Flag | No | No |
| SoftStart | No | No |
| Sync Pin | No | No |
| Flyback | No | No |
| RegType | Switching Regulator | Switching Regulator |
| Temperature Min | -40 deg C | -40 deg C |
| Temperature Max | 125 deg C | 125 deg C |
| Adjustable Output | Yes, No | Yes |
| Adj Switch Frequency | No | No |
| PWM Mode | Voltage with Vin Feedforward | Voltage Mode Control |
| Topology | Buck | Buck |
| Special Features | Internal Type 3 compensation, 2% output voltage accuracy, SIMPLE SWITCHER regulator | 500 kHz Switching Frequency |
| Step-Down | Yes | Yes |
| Multiple Output Capability | No | No |
| Output Power | Undefined Watt | |
| Output Voltage | 3.3, 12, Undefined, 5 Volt | |
| Output Range | 12V, 1.23V to 37V, 3.3V, 5V | |
| Switching Frequency | 260 kHz | 500 kHz |
| Regulator Family | SIMPLE SWITCHER | SIMPLE SWITCHER |
| Synchronous Rectification | No | No |
LM2678 芯片订购型号
| Part Number(s) (NSID) |
Top View | Availability | Budgetary Pricing | Pack Size |
|---|---|---|---|---|
| LM2678S-12/NOPB LM2678S-12 |
 TO-263 |
Full production Lead Time: 16 weeks |
$3.25 each at 1K+ pcs | rail of 45  |
| LM2678S-3.3/NOPB LM2678S-3.3 |
TO-263 |
Full production Lead Time: 16 weeks |
$3.25 each at 1K+ pcs | rail of 45 |
| LM2678S-5.0/NOPB LM2678S-5.0 |
TO-263 |
Full production Lead Time: 22 weeks |
$3.25 each at 1K+ pcs | rail of 45 |
| LM2678S-ADJ/NOPB LM2678S-ADJ |
TO-263 |
Full production Lead Time: 14 weeks |
$3.25 each at 1K+ pcs | rail of 45 |
| LM2678SD-12/NOPB LM2678SD-12 |
 LLP |
Full production Lead Time: 6 weeks |
$3.25 each at 1K+ pcs | reel of 250  |
| LM2678SD-3.3/NOPB LM2678SD-3.3 |
LLP |
Full production Lead Time: 12 weeks |
$3.25 each at 1K+ pcs | reel of 250 |
| LM2678SD-5.0/NOPB LM2678SD-5.0 |
LLP |
Full production Lead Time: 6 weeks |
$3.25 each at 1K+ pcs | reel of 250 |
| LM2678SD-ADJ/NOPB LM2678SD-ADJ setTimeout('show |
LLP |
Full production Lead Time: 16 weeks |
$3.25 each at 1K+ pcs | reel of 250 |
| LM2678SDX-12 | LLP |
Full production Lead Time: 16 weeks |
$3.25 each at 1K+ pcs | reel of 2500 |
| LM2678SDX-3.3 | LLP |
Full production Lead Time: 16 weeks |
$3.25 each at 1K+ pcs | reel of 2500 |
| LM2678SDX-5.0/NOPB LM2678SDX-5.0 |
LLP |
Full production Lead Time: 6 weeks |
$3.25 each at 1K+ pcs | reel of 2500 |
| LM2678SDX-ADJ/NOPB LM2678SDX-ADJ |
LLP |
Full production Lead Time: 6 weeks |
$3.25 each at 1K+ pcs | reel of 2500 |
| LM2678SX-12/NOPB | TO-263 |
Full production Lead Time: 10 weeks |
$3.25 each at 1K+ pcs | reel of 500 |
| LM2678SX-3.3/NOPB LM2678SX-3.3 |
TO-263 |
Full production Lead Time: 10 weeks |
$3.25 each at 1K+ pcs | reel of 500 |
| LM2678SX-5.0/NOPB LM2678SX-5.0 |
TO-263 |
Full production Lead Time: 6 weeks |
$3.25 each at 1K+ pcs | reel of 500 |
| LM2678SX-ADJ/NOPB LM2678SX-ADJ |
TO-263 |
Full production Lead Time: 10 weeks |
$3.25 each at 1K+ pcs | reel of 500 |
| LM2678T-12/NOPB LM2678T-12 |
 TO-220 |
Full production Lead Time: 6 weeks |
$3.25 each at 1K+ pcs | rail of 45 |
| LM2678T-3.3/NOPB LM2678T-3.3 |
TO-220 |
Full production Lead Time: 8 weeks |
$3.25 each at 1K+ pcs | rail of 45 |
| LM2678T-5.0/NOPB LM2678T-5.0 |
TO-220 |
Full production Lead Time: 16 weeks |
$3.25 each at 1K+ pcs | rail of 45 |
| LM2678T-ADJ/NOPB LM2678T-ADJ |
TO-220 |
Full production Lead Time: 16 weeks |
$3.25 each at 1K+ pcs | rail of 45 |
LM2678 停产Obsolete Versions
| Part Number(s) | Obsolete Part | Alternate Part or Supplier | Last Time Buy Date |
|---|---|---|---|
| LM2678LD-12 | NONE | NONE | 30-Jan-04 |
| LM2678LD-3.3 | NONE | NONE | 30-Jan-04 |
| LM2678LD-5.0 | NONE | NONE | 30-Jan-04 |
| LM2678LD-ADJ | NONE | NONE | 30-Jan-04 |
| LM2678LDX-12 | NONE | NONE | 30-Jan-04 |
| LM2678LDX-3.3 | NONE | NONE | 30-Jan-04 |
| LM2678LDX-5.0 | NONE | NONE | 30-Jan-04 |
| LM2678LDX-ADJ | NONE | NONE | 30-Jan-04 |
LM2678 应用技术支持与电子电路设计开发资源下载 Documents
- LM2678 数据手册DataSheet下载. pdf
- LM2678 封装形式尺寸图
- AN-1061: Application Note 1061 Power Conversion in Line-Powered Equipment
- AN-1135: Application Note 1135 LM267X 3A, 5A Evaluation Boards
- AN-1157: Application Note 1157 Positive to Negative Buck‐Boost Converter Using LM267X SIMPLE SWITCHER® Regulators
- AN-1120: Application Note 1120 LM2678-5.0EVAL 1 Amp Step-Down High-Efficiency SIMPLE SWITCHER Evaluation Board
- AN-1229: Application Note 1229 SIMPLE SWITCHER PCB Layout Guidelines