SLVAFC5 March   2022 TPS629210 , TPS629210-Q1

 

  1.   Trademarks
  2. 1Inverting Buck – Boost Topology
    1. 1.1 Concept
    2. 1.2 Output Current Calculations
    3. 1.3 VIN and VOUT Range
  3. 2Digital Pin Configurations
    1. 2.1 Enable Pin
    2. 2.2 MODE/S-CONF Pin
    3. 2.3 Power Good Pin
  4. 3Design Considerations
    1. 3.1 Input Capacitor Selection
    2. 3.2 Output Inductor Selection
    3. 3.3 Stability Limits and Output Capacitor Selection
  5. 4Layout Considerations
  6. 5How to Modify a Buck to Inverting Buck-Boost?
  7. 6Typical Performance and Waveforms
  8. 7Conclusion
  9. 8References

6 Typical Performance and Waveforms

The application circuit shown in Figure 6-1 is used to generate the data for typical performance. L1 is a 2.2 µH inductor from Coilcraft, whereas a 2.2 µH XGL3530-222MEC is used. The output capacitors used 3x22 µF, 10 V, 0603, X5R ceramic capacitor. The input capacitor used 10 μF, 25V, 0603, X5R. Unless otherwise specified, VIN = 12 V and VOUT = –3.3 V, IOUT=0 A to 0.76 A, 2.5 MHz, Auto PFM/PWM, internal feedback (VSET).

GUID-20220207-SS0I-ZZV8-4PPH-ZR7BDGCSSTQV-low.png Figure 6-1 Schematic of Tested Circuit
GUID-20220207-SS0I-G1P5-SVNP-NSXX68QBRR7Q-low.png Figure 6-2 Efficiency with VOUT = –3.3 V
GUID-20220207-SS0I-S293-WJC5-KDZHSFJ63VWM-low.png Figure 6-3 Load Regulation with VOUT = –3.3 V
GUID-20220207-SS0I-GJKC-QFR6-SF3JZV96TCL6-low.png Figure 6-4 Line Regulation with VOUT = –3.3 V , IOUT = 0 A and 0.3 A
GUID-20220207-SS0I-VGFJ-6TCP-9ZWJKJ1DWTQQ-low.png Figure 6-5 Loop Response with VIN =12 V, VOUT = –3.3 V, IOUT = 0.5A
GUID-20220207-SS0I-JFGP-KM5W-MSSMBXV6NN7Z-low.png Figure 6-6 Output Voltage Ripple with VIN = 12 V, VOUT = -3.3 V, IOUT = 0 A
GUID-20220207-SS0I-LC3R-GZ5R-P4GGKCSZXD0F-low.png Figure 6-7 Output Voltage Ripple with VIN = 12 V, VOUT = -3.3 V, IOUT = 0.5 A
GUID-20220207-SS0I-RVQ6-NB1V-LZDCVCDSQ1W1-low.png Figure 6-8 Input Voltage Ripple with VIN = 12 V , VOUT = -3.3 V, IOUT = 0.5 A
GUID-20220207-SS0I-VKFW-KM5L-WM0FWF732CB0-low.png Figure 6-9 Enable Start up with VIN = 12 V, VOUT = -3.3 V, IOUT = 0.5 A
GUID-20220207-SS0I-FTVR-HJ4Z-BGD8QPZGFJBN-low.png Figure 6-10 Enable shutdown with VIN= 12 V, VOUT = -3.3 V, IOUT = 0.5 A
GUID-20220207-SS0I-4KS8-P264-2Z2L3KDL7FBK-low.png Figure 6-11 Load Transient with VIN = 12 V, VOUT = -3.3 V, IOUT = 0.1 A to 0.6 A, Slew rate 1A/μs
GUID-20220207-SS0I-B3N4-MJML-GF00CXJHKN3K-low.png Figure 6-12 Thermal Performance with VIN = 12 V, VOUT =-3.3 V, IOUT = 0.76 A, 10 mimutes soaking