SLVS038I January   1989  – July 2016 TL2842 , TL2843 , TL2844 , TL2845 , TL3842 , TL3843 , TL3844 , TL3845

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 Pulse-by-Pulse Current Limiting
      2. 7.3.2 Error Amplifier With Low Output Resistance
      3. 7.3.3 High-Current Totem-Pole Output
    4. 7.4 Device Functional Modes
      1. 7.4.1 Shutdown Technique
      2. 7.4.2 Slope Compensation
  8. 8 Application and Implementation
    1. 8.1 Typical Application
      1. 8.1.1 Design Requirements
      2. 8.1.2 Detailed Design Procedure
        1. 8.1.2.1 Current-Sense Circuit
        2. 8.1.2.2 Error-Amplifier Configuration
        3. 8.1.2.3 Oscillator Section
      3. 8.1.3 Application Curve
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Feedback Traces
      2. 10.1.2 Input/Output Capacitors
      3. 10.1.3 Compensation Components
      4. 10.1.4 Traces and Ground Planes
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Receiving Notification of Documentation Updates
    2. 11.2 Related Links
    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

封装选项

请参考 PDF 数据表获取器件具体的封装图。

机械数据 (封装 | 引脚)
  • D|8
  • D|14
  • P|8
散热焊盘机械数据 (封装 | 引脚)
订购信息

8 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality.

8.1 Typical Application

The following application is an open-loop laboratory test fixture. This circuit demonstrates the setup and use of the TL284x and TL384x devices and their internal circuitry.

In the open-loop laboratory test fixture (see Figure 13), high peak currents associated with loads necessitate careful grounding techniques. Timing and bypass capacitors should be connected close to the GND terminal in a single-point ground. The transistor and 5-kΩ potentiometer sample the oscillator waveform and apply an adjustable ramp to the ISENSE terminal.

TL2842 TL2843 TL2844 TL2845 TL3842 TL3843 TL3844 TL3845 openloop_slvs038.gif Figure 13. Open-Loop Laboratory Test Fixture

8.1.1 Design Requirements

The design techniques in the following sections may be used for power supply PWM applications which fall within the following requirements.

  • 500-kHz or lower operation
  • 30-V or less output voltage
  • 200-mA or less output current

8.1.2 Detailed Design Procedure

8.1.2.1 Current-Sense Circuit

TL2842 TL2843 TL2844 TL2845 TL3842 TL3843 TL3844 TL3845 app2_slvs038.gif
A. Peak current (IS) is determined by the formula: TL2842 TL2843 TL2844 TL2845 TL3842 TL3843 TL3844 TL3845 note_eqn1_slvs038.gif A small RC filter formed by resistor Rf and capacitor Cf may be required to suppress switch transients.
Figure 14. Current-Sense Circuit Schematic

8.1.2.2 Error-Amplifier Configuration

TL2842 TL2843 TL2844 TL2845 TL3842 TL3843 TL3844 TL3845 app1_slvs038.gif
A. Error amplifier can source or sink up to 0.5 mA.
Figure 15. Error-Amplifier Configuration Schematic

8.1.2.3 Oscillator Section

TL2842 TL2843 TL2844 TL2845 TL3842 TL3843 TL3844 TL3845 app3_slvs038.gif
A. For RT > 5 kΩ: TL2842 TL2843 TL2844 TL2845 TL3842 TL3843 TL3844 TL3845 note_eqn2_slvs038.gif
Figure 16. Oscillator Section Schematic

8.1.3 Application Curve

The application curve shows oscillator characteristics for chosen capacitor and resistor values.

TL2842 TL2843 TL2844 TL2845 TL3842 TL3843 TL3844 TL3845 D009_SLVS038.gif Figure 17. Supply Current vs Supply Voltage