SNVA432D March   2010  – January 2022 LM21305

 

  1.   Trademarks
  2. 1 LM21305 Overview
  3. 2 Typical Application Circuit
  4. 3 Evaluation Board Schematic
  5. 4 Evaluation Board Bill of Materials (BOM)
  6. 5 Connection Descriptions
  7. 6 Jumper Settings
  8. 7 Other Design Examples
  9. 8 Typical Performance Characteristics
  10. 9 Component Selection
    1. 9.1 Input Capacitors
    2. 9.2 AVIN Filter
    3. 9.3 Switching Frequency Selection
    4. 9.4 Inductor
    5. 9.5 Output Capacitor
    6. 9.6 Compensation Circuit
  11. 10PCB Layout
  12. 11Revision History

6 Jumper Settings

Terminal SilkscreenDescription
JP1Sets the AVIN of the LM21305. Pins 2 and 3 connected gives AVIN = PVIN. Pins 1 and 2 connected gives AVIN = AVIN_EXT.
Default: Pins 2 and 3 connected.
J1Enables the on-board LED, LD1. When J1 is ON, LD1 will be ON if PGOOD is high. When J1 is OFF, power used to drive LD1 is saved.
Default: ON
J2Synchronizing clock input. When J2 is ON, C1 is connected to ground and switching frequency is set by the on-board resistor R4. When J2 is OFF, the switch node waveform will be synchronized to the clock source connected to J2.
Default: ON
J3Only should be connected when AVIN = 5 V. When AVIN is below 5 V, and especially below 3.3 V, connecting J3 can result in better efficiency.
Default: OFF
Caution: if AVIN > 5.5 V, connecting J3 can damage the device.