SNVSAF7B August   2016  – February 2017 LM27762

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 Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Undervoltage Lockout
      2. 7.3.2 Input Current Limit
      3. 7.3.3 PFM Operation
      4. 7.3.4 Output Discharge
      5. 7.3.5 Power Good Output (PGOOD)
      6. 7.3.6 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Shutdown Mode
      2. 7.4.2 Enable Mode
  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 Custom Design With WEBENCH® Tools
        2. 8.2.2.2 Positive Low-Dropout Linear Regulator and OUT+ Voltage Setting
        3. 8.2.2.3 Charge-Pump Voltage Inverter
        4. 8.2.2.4 Negative Low-Dropout Linear Regulator and OUT- Voltage Setting
        5. 8.2.2.5 External Capacitor Selection
          1. 8.2.2.5.1 Charge-Pump Output Capacitor
          2. 8.2.2.5.2 Input Capacitor
          3. 8.2.2.5.3 Flying Capacitor
          4. 8.2.2.5.4 LDO Output Capacitor
        6. 8.2.2.6 Power Dissipation
      3. 8.2.3 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 Development Support
        1. 11.1.1.1 Custom Design With WEBENCH® Tools
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Community Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

1 Features

  • Generates Low-Noise Adjustable Positive Supply Voltage Between 1.5 V and 5 V and Negative Supply Voltage Between –1.5 V and –5 V
  • Input Voltage Range 2.7 V to 5.5 V
  • ±250-mA Output Current
  • Inverting Charge Pump Followed by Negative LDO
  • 2-MHz Low-Noise Fixed-Frequency Operation
  • 2.5-Ω Inverter Output Impedance, VIN = 5 V
  • Negative LDO Dropout Voltage 30 mV at 100 mA, VOUT = –5 V
  • Positive LDO with 45-mV Dropout Voltage at 100 mA, VOUT = 5 V
  • 390-µA Quiescent Current (Typical)
  • Shutdown Quiescent Current to 0.5 µA (Typical)
  • Current Limit and Thermal Protection
  • Power Good Pin (Active Low)
  • Create a Custom Design Using the LM27762 With the WEBENCH® Power Designer

2 Applications

  • Hi-Fi Audio Headphone Amplifiers
  • Operational Amplifier Power Biasing
  • Powering Data Converters
  • Wireless Communication Systems
  • Interface Power Supplies
  • Handheld Instrumentation

3 Description

The LM27762 delivers very low-noise positive and negative outputs that are adjustable between ±1.5 V and ±5 V. Input-voltage range is from 2.7 V to 5.5 V, and output current goes up to ±250 mA. With an operating current of only 390 µA and 0.5-µA typical shutdown current, the LM27762 provides ideal performance for power amplifier and DAC bias and other high-current, low-noise negative voltage needs. The device provides a small solution size with few external components.

Negative voltage is generated by a regulated inverting charge pump followed by a low-noise negative LDO. The inverting charge pump of the LM27762 device operates at 2-MHz (typical) switching frequency to reduce output resistance and voltage ripple. Positive voltage is generated from the input by a low-noise positive LDO.

Positive and negative outputs of LM27762 have dedicated enable inputs. These outputs support independent timing for the positive and negative rails for specific system power-sequence needs. Enable inputs can be also shorted together and connected to the input voltage. The LM27762 has an optional Power Good feature.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (NOM)
LM27762 WSON (12) 2.00 mm × 3.00 mm
  1. For all available packages, see the orderable addendum at the end of the data sheet.

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Simplified Schematic

LM27762 simp_schem_snvsaf7.gif