SLOA284A january   2020  – may 2023 AFE5832 , AFE5832LP , ISO7741 , ISOW7841 , LM25037 , LM25180 , LM5180 , LM5181 , LM5181-Q1 , TX7316 , TX7332

 

  1.   1
  2.   Designing Bipolar High Voltage SEPIC Supply for Ultrasound Smart Probe
  3.   Trademarks
  4. 1Introduction
    1. 1.1 Key Design Challenges
    2. 1.2 Potential Topologies for Generating High Voltage Supply
  5. 2Design of high voltage circuit using SEPIC topology
    1. 2.1 TI HV Supply Architecture Using SEPIC Topology
  6. 3Test Results
    1. 3.1 Efficiency and Load Regulation
    2. 3.2 Output Ripple Measurement
    3. 3.3 Load Transient Test
    4. 3.4 Noise Measurement
    5. 3.5 Thermal Performance
  7. 4Possible Variants of the Design
    1. 4.1 Option 1: Programmable Output Voltage
    2. 4.2 Option 2: Support Input From 1S Li-Ion Battery
    3. 4.3 Option 3: Output Voltage Up to ±100 V
  8. 5Layout Guidelines
  9. 6Clock Synchronization
  10. 7Summary
  11. 8References
  12. 9Revision History

4.2 Option 2: Support Input From 1S Li-Ion Battery

1S Li-Ion battery has a typical operating voltage range of 3.0 V to 4.2 V. To generate an output voltage of +/- 80V, the existing SEPIC needs a PWM controller that can achieve high duty cycle > 95%. At these very high duty cycle there are practical limitations such as: parasitics which affect the turn-on and turn-off time of the MOSFET, lower available time for energy transfer from primary to secondary side which limit the achievable maximum output voltage. Hence an intermediate boost stage is required to be added, as shown in Figure 4-3.

GUID-67735107-9F06-42E8-AC19-A836E99EBC12-low.gifFigure 4-3 Case of 1S Battery