SNVS087AE October   2000  – May 2015 LP3985

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  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 Performance Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 No-Load Stability
      2. 7.3.2 On/Off Input Operation
      3. 7.3.3 Fast On-Time
    4. 7.4 Device Functional Modes
      1. 7.4.1 Operation with VOUT(TARGET) + 0.3 V ≤ VIN ≤ 6 V
      2. 7.4.2 Operation Using the EN Pin
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 External Capacitors
        2. 8.2.2.2 Input Capacitor
        3. 8.2.2.3 Output Capacitor
        4. 8.2.2.4 Capacitor Characteristics
        5. 8.2.2.5 Noise Bypass Capacitor
        6. 8.2.2.6 Thermal Considerations
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Examples
    3. 10.3 DSBGA Mounting
    4. 10.4 DSBGA Light Sensitivity
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Trademarks
    3. 11.3 Electrostatic Discharge Caution
    4. 11.4 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

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1 Features

  • Input Voltage: 2.5 V to 6 V
  • 100-mV Maximum Dropout with 150-mA Load
  • 150-mA Verified Output
  • 50-dB PSRR at 1 kHz at VIN = VOUT + 0.2 V
  • ≤ 1.5-μA Quiescent Current when Shut Down
  • Fast Turn-On time: 200 μs (typ.)
  • 30-μVRMS Output Noise (typical) over 10 Hz to 100 kHz
  • −40°C to 125°C Junction Temperature Range for Operation
  • 2.5-V, 2.6-V, 2.7-V, 2.8-V, 2.85-V, 2.9-V, 3-V, 3.1-V, 3.2-V, 3.3-V, 4.7-V, 4.75-V, 4.8-V and 5-V Outputs Standard
  • Logic Controlled Enable
  • Stable with Ceramic and High-Quality Tantalum Capacitors
  • Fast Turnon
  • Thermal Shutdown and Short-Circuit Current Limit

2 Applications

  • CDMA Cellular Handsets
  • Wideband CDMA Cellular Handsets
  • GSM Cellular Handsets
  • Portable Information Appliances

Simplified Schematic

LP3985 10136402.gif

3 Description

The LP3985 is designed for portable and wireless applications with demanding performance and space requirements. LP3985 performance is optimized for battery-powered systems to deliver ultra low noise, extremely low dropout voltage, and low quiescent current. Regulator ground current increases only slightly in dropout, further prolonging the battery life.

The LP3985 is stable with a small 1-µF ±30% ceramic or high-quality tantalum output capacitor. The DSBGA requires the smallest possible PC board area - the total application circuit area can be less than 2 mm x 2.5 mm, a fraction of a 1206 case size.

An optional external bypass capacitor reduces the output noise without slowing down the load transient response. Fast startup time is achieved by utilizing an internal power-on circuit that actively pre-charges the bypass capacitor.

Power supply rejection is better than 50 dB at low frequencies and starts to roll off at 1 kHz. High power supply rejection is maintained down to low input voltage levels common to battery operated circuits.

The device is ideal for mobile phone and similar battery-powered wireless applications. It provides up to 150 mA, from a 2.5-V to 6-V input. The LP3985 consumes less than 1.5 µA in disable mode and has fast turn-on time less than 200 µs.

The LP3985 is available with fixed output voltages from 2.5 V to 5 V. Contact Texas Instruments Sales for specific voltage option needs.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE
LP3985 DSBGA (5) 1.502 mm x 1.045 mm (MAX)
SOT-23 (5) 2.90 mm x 1.60 mm (NOM)
  1. For all available packages, see the Package Option Addendum at the end of the datasheet.