SNOS510Q November   1999  – October 2016 LP2985LV-N

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 Multiple Voltage Options
      2. 7.3.2 Output Voltage Accuracy
      3. 7.3.3 Ultra-Low-Dropout Voltage
      4. 7.3.4 Low Ground Current
      5. 7.3.5 Sleep Mode
      6. 7.3.6 Internal Protection Circuitry
        1. 7.3.6.1 Short Circuit Protection (Current Limit)
        2. 7.3.6.2 Thermal Protection
      7. 7.3.7 Enhanced Stability
      8. 7.3.8 Low Noise
    4. 7.4 Device Functional Modes
      1. 7.4.1 Operation with VOUT(TARGET) + 0.6 V ≥ VIN > 16 V
      2. 7.4.2 Operation With ON/OFF Control
  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
          1. 8.2.2.1.1 Input Capacitor
          2. 8.2.2.1.2 Output Capacitor
          3. 8.2.2.1.3 Noise Bypass Capacitor
        2. 8.2.2.2 Capacitor Characteristics
          1. 8.2.2.2.1 Tantalum
        3. 8.2.2.3 On/OFF Input Operation
        4. 8.2.2.4 Reverse Input-Output Voltage
        5. 8.2.2.5 Power Dissipation
        6. 8.2.2.6 Estimating Junction Temperature
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
    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. 11.1.2 Receiving Notification of Documentation Updates
    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

7 Detailed Description

7.1 Overview

The LP2985LV-N family of fixed-output, ultra-low-dropout and low-noise regulators offers exceptional, cost-effective performance for battery-powered applications. Available in output voltages from 1.5 V to 2 V, the family has an output voltage tolerance of 1% for the A version (1.5% for the non-A version) and is capable of delivering 150-mA continuous load current. Standard regulator features, such as overcurrent and overtemperature protection, are also included.

Using an optimized vertically integrated PNP (VIP) process, the LP2985LV-N contains several features to facilitate battery-powered designs:

  • Multiple voltage options
  • Low dropout voltage, typical dropout of 280 mV at 150-mA load current and 120 mV at 50-mA load current.
  • Low quiescent current and low ground current, typically 825-μA at 150-mA load, and 75 μA at 1-mA load.
  • A shutdown feature is available, allowing the regulator to consume only 0.01 µA typically when the ON/OFF pin is pulled low.
  • Overtemperature protection and overcurrent protection circuitry is designed to safeguard the device during unexpected conditions
  • Enhanced stability: The LP2985LV-N is stable with output capacitor ESR as low as 5 mΩ, which allows the use of ceramic capacitors on the output.
  • Low noise: A BYPASS pin allows for low-noise operation, with a typical output noise of 30 µVRMS, with the use of a 10-nF bypass capacitor.

7.2 Functional Block Diagram

LP2985LV-N fbd_snos150.png

7.3 Feature Description

7.3.1 Multiple Voltage Options

In order to meet different application requirement, the LP2985LV-N family provide multiple fixed output options from 1.5 V to 2 V. Contact your regional TI sales team for custom voltage options.

7.3.2 Output Voltage Accuracy

Output voltage accuracy specifies minimum and maximum output voltage error, relative to the expected nominal output voltage stated as a percent. This accuracy error includes the errors introduced by the internal reference and the load and line regulation across the full range of rated load and line operating conditions over temperature, unless otherwise specified by the Electrical Characteristics. Output voltage accuracy also accounts for all variations between manufacturing lots.

7.3.3 Ultra-Low-Dropout Voltage

Generally speaking, the dropout voltage often refers to the voltage difference between the input and output voltage (VDO = VIN – VOUT), where the current pass transistor loses its voltage-controlled current capability and the collector (VOUT) to emitter (VIN) voltage becomes constant for a given current and is characterized by the classic VCE(SAT) of the PNP transistor. VDO indirectly specifies a minimum input voltage above the nominal programmed output voltage at which the output voltage is expected to remain within its accuracy boundary. If the input falls below this VDO limit (VIN < VOUT + VDO), then active regulation of the output voltage is no longer possible, and the output voltage decreases as the input voltage falls.

7.3.4 Low Ground Current

The LP2985LV-N device uses a vertical PNP process which allows for quiescent currents that are considerably lower than those associated with traditional lateral PNP regulators, typically 825 μA at 150-mA load.

7.3.5 Sleep Mode

When the ON/OFF pin is pulled to a low level the LP2985LV-N enters sleep mode, and less than 2-μA quiescent current is consumed. This function is designed for the application which needs a sleep mode to effectively enhance battery life cycle.

7.3.6 Internal Protection Circuitry

7.3.6.1 Short Circuit Protection (Current Limit)

The internal current limit circuit is used to protect the LDO against high-load current faults or shorting events. The LDO is not designed to operate in a steady-state current limit. During a current-limit event, the LDO sources constant current. Therefore, the output voltage falls when load impedance decreases. Note also that if a current limit occurs and the resulting output voltage is low, excessive power may be dissipated across the LDO, resulting in a thermal shutdown of the output.

A foldback feature limits the short-circuit current to protect the regulator from damage under all load conditions. If VOUT is forced below 0 V before EN goes high and the load current required exceeds the foldback current limit, the device may not start up correctly.

7.3.6.2 Thermal Protection

The LP2985LV-N contains a thermal shutdown protection circuit to turn off the output current when excessive heat is dissipated in the LDO. The thermal time-constant of the semiconductor die is fairly short, and thus the output cycles on and off at a high rate when thermal shutdown is reached until the power dissipation is reduced.

The internal protection circuitry of the LP2985LV-N is designed to protect against thermal overload conditions. The circuitry is not intended to replace proper heat sinking. Continuously running the device into thermal shutdown degrades its reliability.

7.3.7 Enhanced Stability

The LP2985LV-N is designed specifically to work with ceramic output capacitors, utilizing circuitry which allows the regulator to be stable across the entire range of output current with an output capacitor whose ESR is as low as 5 mΩ. For output capacitor requirement, refer to Output Capacitor.

7.3.8 Low Noise

The LP2985LV-N includes a low-noise reference ensuring minimal noise during operation because the internal reference is normally the dominant term in noise analysis. Further noise reduction can be achieved by adding an external bypass bapacitor between the BYPASS pin and the GND pin.

7.4 Device Functional Modes

7.4.1 Operation with VOUT(TARGET) + 0.6 V ≥ VIN > 16 V

The device operate if the input voltage is equal to, or exceeds VOUT(TARGET) + 0.6 V. At input voltages below the minimum VIN requirement, the devices do not operate correctly and output voltage may not reach target value.

7.4.2 Operation With ON/OFF Control

If the voltage on the ON/OFF pin is less than 0.15 V, the device is disabled, and in this state shutdown current does not exceed 2 μA. Raising ON/OFF above 1.6 V initiates the start-up sequence of the device.