SLVS033G February   1990  – July 2015 LT1054


  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Pin Configuration and Functions
  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. Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Reference and Error Amplifier for Regulation
      2. 7.3.2 External Oscillator Synchronization
      3. 7.3.3 Output Current and Voltage Loss
      4. 7.3.4 Reference Voltage
    4. 7.4 Device Functional Modes
      1. 7.4.1 Main Operation
      2. 7.4.2 Shutdown
  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. Output Voltage Programming
        2. Capacitor Selection
        3. Output Ripple
        4. Power Dissipation
      3. 8.2.3 Application Curve
    3. 8.3 System Examples
  9. Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Community Resources
    2. 11.2 Trademarks
    3. 11.3 Electrostatic Discharge Caution
    4. 11.4 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • P|8
  • DW|16
Thermal pad, mechanical data (Package|Pins)
Orderable Information

9 Power Supply Recommendations

The LT1054 alternately charges CIN to the input voltage when CIN is switched in parallel with the input supply and then transfers charge to COUT when CIN is switched in parallel with COUT. Switching occurs at the oscillator frequency. During the time that CIN is charging, the peak supply current will be approximately equal to 2.2 times the output current. During the time that CIN is delivering charge to COUT the supply current drops to approximately 0.2 times the output current. An input supply bypass capacitor will supply part of the peak input current drawn by the LT1054 and average out the current drawn from the supply. A minimum input supply bypass capacitor of 2µF, preferably tantalum or some other low ESR type is recommended. A larger capacitor may be desirable in some cases, for example, when the actual input supply is connected to the LT1054 through long leads, or when the pulse current drawn by the LT1054 might affect other circuitry through supply coupling.

In addition to being the output terminal, VOUT is tied to the substrate of the device. Special care must be taken in LT1054 circuits to avoid making VOUT positive with respect to any of the other terminals. For circuits with the output load connected from VCC to VOUT or from some external positive supply voltage to VOUT, an external transistor must be added (see Figure 30). This transistor prevents VOUT from being pulled above GND during startup. Any small general-purpose transistor such as a 2N2222 or a 2N2219 device can be used. Resistor R1 should be chosen to provide enough base drive to the external transistor so that it is saturated under nominal output voltage and maximum output current conditions.

Equation 11. LT1054 Eq11_R1-F4_SLVS033.gif
LT1054 crcuit_w_load_cnxt_vcc_vout_slvs033.gifFigure 30. Circuit With Load Connected from VCC to VOUT