SNVAA61 February   2023 LM5168 , LM5168-Q1 , LM5169 , LM5169-Q1

 

  1.   Inverting Buck-Boost Application for LM5168
  2.   Trademarks
  3. 1Inverting Buck-Boost Topology
    1. 1.1 Concept
    2. 1.2 Output Current Calculations
    3. 1.3 Voltage Range of Inverting Buck-Boost Configuration
  4. 2Design Considerations
    1. 2.1 Bypass Capacitor and Optional Schottky Diode
  5. 3External Components
    1. 3.1 Capacitor Selection
    2. 3.2 Inductor Selection
  6. 4Digital Pin Configurations
    1. 4.1 Optional Enable (EN) Level Shifter
    2. 4.2 Power-Good (PG) Pin
  7. 5Typical Performance
    1. 5.1 VOUT = -12 V Typical Performance
    2. 5.2 VOUT = -24 V Typical Performance
    3. 5.3 VOUT = -48 V Typical Performance
  8. 6Conclusion
  9. 7References

5.1 VOUT = -12 V Typical Performance

Figure 5-1 Schematic
VOUT = -12 V FSW = 500 kHz (AUTO)
Figure 5-3 Efficiency vs. Load Current
GUID-20230201-SS0I-XFFK-SHZP-N2RMBML6WLKS-low.png
VOUT = -12 V ILOAD = 138 mA
Figure 5-5 Startup at VIN = 12 V
GUID-20230201-SS0I-ZFWD-D6ST-QTC8HPGPJTG4-low.png
VOUT = -12 V ILOAD = 138 mA
Figure 5-7 Startup at VIN = 24 V
GUID-20230126-SS0I-MZKH-M58N-D1860FHZ6WGT-low.png
VOUT = -12 V ILOAD = 0 mA to 138 mA
Figure 5-9 Full Load Transient at VIN = 12 V
GUID-20230126-SS0I-K6RT-V0W5-D4RHWHQBBS19-low.png
VOUT = -12 V ILOAD = 0 mA to 189 mA
Figure 5-11 Full Load Transient at VIN = 24 V
GUID-20230201-SS0I-5N2T-BHTR-TWRPMKD1L14B-low.png
VOUT = -12 V ILOAD = 0 A
Figure 5-13 No Load Output Ripple at VIN = 12 V
GUID-20230201-SS0I-XRV0-XVK5-RLMJWXLLBFB4-low.png
VOUT = -12 V ILOAD = 0 A
Figure 5-15 No Load Output Ripple at VIN = 24 V
Figure 5-2 Bill of Materials
VOUT = -12 V FSW = 500 kHz (AUTO)
Figure 5-4 Load Regulation vs. Load Current
GUID-20230201-SS0I-NNQM-SJPC-0XNCMTXXDVDL-low.png
VOUT = -12 V ILOAD = 138 mA
Figure 5-6 Shutdown at VIN = 12 V
GUID-20230201-SS0I-LT7C-G48J-999JFR60VGJR-low.png
VOUT = -12 V ILOAD = 138 mA
Figure 5-8 Shutdown at VIN = 24 V
GUID-20230126-SS0I-JJH1-VGVZ-HVCWS5ZMSHGL-low.png
VOUT = -12 V ILOAD = 50 mA to 138 mA
Figure 5-10 Load Transient at VIN = 12 V
GUID-20230126-SS0I-4ZX2-FH0X-VNXJ1D47FWJC-low.png
VOUT = -12 V ILOAD = 50 mA to 189 mA
Figure 5-12 Load Transient at VIN = 24 V
GUID-20230201-SS0I-9GX5-RCMT-JKQMMXR9VFVG-low.png
VOUT = -12 V ILOAD = 138 mA
Figure 5-14 Full Load Output Ripple at VIN = 12 V
GUID-20230201-SS0I-CFHJ-MMZP-S9J1KK9M0SL2-low.png
VOUT = -12 V ILOAD = 189 mA
Figure 5-16 Full Load Output Ripple at VIN = 24 V