LM3485 Hysteretic PFET Buck Controller
LM3485 特性Features
- Easy to use control methodology
- No control loop compensation required
- 4.5V to 35V wide input range
- 1.242V to VIN adjustable output range
- High Efficiency 93%
- ±1.3% (±2% over temp) internal reference
- 100% duty cycle
- Maximum operating frequency > 1MHz
- Current limit protection
- MSOP-8
LM3485 概述Description
The LM3485 is a high efficiency PFET switching regulator controller that can be used to quickly and easily develop a small, low cost, switching buck regulator for a wide range of applications. The hysteretic control architecture provides for simple design without any control loop stability concerns using a wide variety of external components. The PFET architecture also allows for low component count as well as ultra-low dropout, 100% duty cycle operation. Another benefit is high efficiency operation at light loads without an increase in output ripple.
Current limit protection is provided by measuring the voltage across the PFET’s RDS(ON), thus eliminating the need for a sense resistor. The cycle-by-cycle current limit can be adjusted with a single resistor, ensuring safe operation over a range of output currents.
LM3485 应用Applications
- Set-Top Box
- DSL/Cable Modem
- PC/IA
- Auto PC
- TFT Monitor
- Battery Powered Portable Applications
- Distributed Power Systems
- Always On Power
LM3485 典型性能Typical Application |
LM3485 功能框图Block Diagram |
LM3485 典型性能Typical Performance |
|---|
LM3485 性能参数Parametrics
| Paramaters / Values | LM3485 | LM1770 | LM1771 | LM25085 | LM3475 | LM3477 | LM3489 |
|---|---|---|---|---|---|---|---|
| Output Current | 4000 mA | 4000 mA | 6000 mA | 5000 mA | 6000 mA | 4000 mA | |
| Input Min Voltage | 4.5 Volt | 2.8 Volt | 2.8 Volt | 4.5 Volt | 2.7 Volt | 2.95 Volt | 4.5 Volt |
| Input Max Voltage | 35 Volt | 5.5 Volt | 5.5 Volt | 42 Volt | 10 Volt | 35 Volt | 35 Volt |
| Output Range | 1.242V to Vin | 0.8V to 4.5V | 0.8V to 4.5V | 1.25V to VIN | 0.8V to Vin | 1.265V min | 1.239V min. |
| Frequency Min | 0 kHz | 300 kHz | 300 kHz | 0 kHz | 500 kHz | 0 kHz | |
| Frequency Max | 1400 kHz | 1000 kHz | 1000 kHz | 1000 kHz | 1400 kHz | 500 kHz | 1400 kHz |
| Feedback Voltage | 1.27 Volt | 0.8 Volt | 0.8 Volt | 1.25 Volt | 0.8 Volt | 1.265 Volt | 1.239 Volt |
| Feedback Tolerance | 2 % | 2 % | 2 % | 2 % | 1.5 % | 1.5 % | 2 % |
| Efficiency (peak) | 93 % | 95 % | 95 % | 95 % | 90 % | ||
| Adj Switch Frequency | Yes | No | No | Yes | No | No | Yes |
| Adjustable Output | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
| Synchronous Rectification | No | Yes | Yes | No | No | No | |
| On/Off Pin | No | No | Yes | Yes | Yes | Yes | Yes |
| PowerGood / Error Flag | No | No | No | No | No | No | No |
| SoftStart | No | Yes | Yes | Yes | Yes | Yes | No |
| Sync Pin | No | No | No | No | No | No | No |
| Inverting | No | Yes | No | Yes | No | Yes | No |
| Flyback | No | No | No | No | No | No | No |
| Lossless Current Sense | Yes | No | No | No | Yes | No | Yes |
| RegType | Switching Controller | Switching Controller | Switching Controller | Switching Controller | Switching Controller | Switching Controller | Switching Controller |
| Temperature Min | -40 deg C | -40 deg C | -40 deg C | -40 deg C | -40 deg C | -40 deg C | -40 deg C |
| Temperature Max | 125 deg C | 125 deg C | 125 deg C | 125 deg C | 125 deg C | 125 deg C | 125 deg C |
| Channels | 1 Channels | 1 Channels | 1 Channels | 1 Channels | 1 Channels | 1 Channels | |
| Special Features | No compensation required; Current limit; PFET controller | No compensation required | Precision enable for sequencing multiple rails | Near constant switching frequency, PFET for 100% duty cycle | Fast transient response; High efficiency; Wide Vin range; 100% duty cycle capable | Hysteretic threshold at 36% of programmed current limit; Vout OVP | No compensation required; Current limit; PFET controller; Enable; Power-saving shutdown mode |
| Topology | Buck | Buck | Buck | Buck | Buck | Buck | Buck |
| PWM Mode | Hysteretic | Constant on-time | Constant on-time | Constant On-Time (COT) | Hysteretic | Current | Hysteretic |
| Step-Down | Yes | No | Yes | Yes | Yes | Yes | Yes |
| Step-Up | 1, No | No | No | No | No | No | |
| Output Min | 1.242 Volt | 0.8 Volt | 0.8 Volt | 1.25 Volt | 0.8 Volt | 1.265 Volt | 1.239 Volt |
| AEC Q-100 Automotive Grade | 1 | 1 | 1 | ||||
| Automotive | Yes | No | Yes |
LM3485 芯片订购型号
| Part Number(s) (NSID) |
Top View | Availability | Budgetary Pricing | Pack Size |
|---|---|---|---|---|
| LM3485MM/NOPB LM3485MM |
 MINI SOIC |
Full production Lead Time: 6 weeks |
$0.55 each at 1K+ pcs | reel of 1000  |
| LM3485MMX/NOPB LM3485MMX |
MINI SOIC |
Full production Lead Time: 8 weeks |
$0.55 each at 1K+ pcs | reel of 3500 |
LM3485 开发工具LM3485EVAL
| Part Number(s) (NSID) | Description | Availability | Budgetary Pricing | Pack Size |
|---|---|---|---|---|
| LM3485EVAL | Hysteretic PFET Buck Controller | Full production Lead Free (RoHS) |
$30.00 each | 1 |
LM3485 标准体系参考Reliability Metrics
| Part Number | Process | EFR Reject | EFR Sample Size | PPM | LTA Rejects | LTA Device Hours | FITS | MTTF (Hours) |
|---|---|---|---|---|---|---|---|---|
| LM3485MM | ABCD150 | 0 | 34175 | 0 | 0 | 4234000 | 1 | 1201409060 |
| LM3485MMX | ABCD150 | 0 | 34175 | 0 | 0 | 4234000 | 1 | 1201409060 |
LM3485 应用技术支持与电子电路设计开发资源下载 Documents
- LM3485 数据手册DataSheet下载. pdf
- LM3485 开发工具LM3485EVAL
- LM3485 封装形式尺寸图
- AN-1227: Application Note 1227 LM3485 Evaluation Board
- AN-1392: Application Note 1392 LM3485 LED Demo Board
- AN-1204: Application Note 1204 LM3478/LM3488 Evaluation Board
- AN-1756: Application Note 1756 LM3481 Evaluation Board
- AN-1471: Application Note 1471 LM3489 Demonstration Board
- LM3485 绿色环保信息