SNVS250F November   2004  – February 2016 LM3670

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Connection Diagram
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Circuit Operation
      2. 7.3.2 Soft Start
      3. 7.3.3 LDO - Low Dropout Operation
    4. 7.4 Device Functional Modes
      1. 7.4.1 PWM Operation
        1. 7.4.1.1 Internal Synchronous Rectification
        2. 7.4.1.2 Current Limiting
      2. 7.4.2 PFM Operation
      3. 7.4.3 Shutdown
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Typical Application: Fixed Output
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Inductor Selection
            1. 8.2.1.2.1.1 Method 1
            2. 8.2.1.2.1.2 Method 2
          2. 8.2.1.2.2 Input Capacitor Selection
          3. 8.2.1.2.3 Output Capacitor Selection
        3. 8.2.1.3 Application Curves
      2. 8.2.2 Typical Application: Adjustable Output
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
          1. 8.2.2.2.1 Output Voltage Selection for Adjustable LM3670
        3. 8.2.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
    2. 11.2 Community Resources
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

1 Features

  • Input Voltage Range: 2.5 V to 5.5 V
  • Adjustable Output Voltages (VOUT): 0.7 V to 2.5 V
  • Fixed Output Voltages: 1.2 V, 1.5 V, 1.6 V, 1.8 V, 1.875 V, 3.3V
  • 15-µA Typical Quiescent Current
  • 350-mA Maximum Load Capability
  • 1-MHz PWM Fixed Switching Frequency (Typical)
  • Automatic PFM and PWM Mode Switching
  • Low Dropout Operation – 100% Duty Cycle Mode
  • Internal Synchronous Rectification for High Efficiency
  • Internal Soft Start
  • 0.1-µA Typical Shutdown Current
  • Current Overload Protection
  • Operates from a Single Li-Ion Cell or Three-Cell NiMH/NiCd Batteries
  • Only Three Tiny Surface-Mount External Components Required (One Inductor, Two Ceramic Capacitors)

2 Applications

  • Mobile Phones and Handheld Devices
  • PDAs
  • Palm-Top PCs
  • Portable Instruments
  • Battery-Powered Devices

3 Description

The LM3670 step-down DC-DC converter is optimized for powering ultralow voltage circuits from a single Li-Ion cell or three-cell NiMH/NiCd batteries. It provides up to 350-mA load current, over an input voltage range from 2.5 V to 5.5 V. There are several different fixed voltage output options available as well as an adjustable output voltage version.

The device offers superior features and performance for mobile phones and similar portable applications with complex power management systems. Automatic intelligent switching between pulse width modulation (PWM) low-noise and pulse frequency modulation (PFM) low-current mode offers improved system control. During full-power operation, a fixed-frequency 1-MHz (typical) PWM mode drives loads from approximately 70 mA to 350 mA maximum, with up to 95% efficiency. Hysteretic PFM mode extends the battery life through reduction of the quiescent current to 15 µA (typical) during light current loads and system standby. Internal synchronous rectification provides high efficiency (90% to 95% typical at loads between 1 mA and 100 mA). In shutdown mode (enable (EN) pin pulled low) the device turns off and reduces battery consumption to 0.1 µA (typical).

The LM3670 is available in a 5-pin SOT-23 package. A high switching frequency (1 MHz typical) allows use of tiny surface-mount components. Only three external surface-mount components, an inductor and two ceramic capacitors, are required.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (NOM)
LM3670 SOT-23 (5) 2.90 mm × 1.60 mm
  1. For all available packages, see the orderable addendum at the end of the data sheet.

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Typical Application: Fixed Output

LM3670 20075801.gif

Typical Application: Adjustable Output Voltage

LM3670 typapp_ADJ.gif