SNVS671F February   2011  – May 2019 LM21212-1

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified Application Circuit
  4. 4 Revision History
  5. 5 Description
  6. 6 Pin Configuration and Functions
    1.     Pin Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Typical Performance Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Frequency Synchronization
      2. 8.3.2 Precision Enable
      3. 8.3.3 UVLO
      4. 8.3.4 Current Limit
      5. 8.3.5 Short-Circuit Protection
      6. 8.3.6 Thermal Protection
      7. 8.3.7 Power-Good Flag
      8. 8.3.8 Light Load Operation
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Detailed Design Procedure
        1. 9.2.1.1 Custom Design With WEBENCH® Tools
        2. 9.2.1.2 Output Voltage
        3. 9.2.1.3 Precision Enable
        4. 9.2.1.4 Soft Start
        5. 9.2.1.5 Inductor Selection
        6. 9.2.1.6 Output Capacitor Selection
        7. 9.2.1.7 Input Capacitor Selection
        8. 9.2.1.8 Control Loop Compensation
      2. 9.2.2 Application Curves
  10. 10Layout
    1. 10.1 Pcb Layout Considerations
    2. 10.2 Thermal Considerations
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
      2. 11.1.2 Development Support
        1. 11.1.2.1 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

封装选项

机械数据 (封装 | 引脚)
散热焊盘机械数据 (封装 | 引脚)

6 Pin Configuration and Functions

PWP Package
20-Pin HTSSOP
Top View
LM21212-1 30119902.gif

Pin Functions

PIN DESCRIPTION
NO. NAME
1 SYNC Frequency synchronization input pin. Applying a clock signal to this pin will force the device to switch at the clock frequency. If left unconnected, the frequency will default to 1 MHz.
2 SS/TRK Soft-start control pin. An internal 2-µA current source charges an external capacitor connected between this pin and AGND to set the output voltage ramp rate during startup. This pin can also be used to configure the tracking feature.
3 EN Active high enable input for the device. If not used, the EN pin can be left open, which goes high due to an internal current source.
4 AVIN Analog input voltage supply that generates the internal bias. It is recommended to connect PVIN to AVIN through a low pass RC filter to minimize the influence of input rail ripple and noise on the analog control circuitry.
5,6,7 PVIN Input voltage to the power switches inside the device. These pins should be connected together at the device. Place a low ESR input capacitance as close as possible to these pins.
8,9,10 PGND Power ground pins for the internal power switches.
11-16 SW Switch node pins. These pins should be tied together locally and connected to the filter inductor.
17 PGOOD Open-drain power good indicator.
18 COMP Compensation pin is connected to the output of the voltage loop error amplifier.
19 FB Feedback pin is connected to the inverting input of the voltage loop error amplifier.
20 AGND Quiet analog ground for the internal reference and bias circuitry.
EP Exposed Pad Exposed metal pad on the underside of the package with an electrical and thermal connection to PGND. TI recommends connecting this pad to the PC board ground plane in order to improve thermal dissipation.