SLVSCK8A November   2014  – December 2014 TPS63024 , TPS630241 , TPS630242

PRODUCTION DATA.  

  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Pin Configuration and Functions
  6. Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Timing Requirements
    7. 6.7 Typical Characteristics
  7. Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Undervoltage Lockout (UVLO)
      2. 7.3.2 Output Discharge Function
      3. 7.3.3 Thermal Shutdown
      4. 7.3.4 Softstart
      5. 7.3.5 Short Circuit Protection
    4. 7.4 Device Functional Modes
      1. 7.4.1 Control Loop Description
      2. 7.4.2 Power Save Mode Operation
      3. 7.4.3 Current Limit
      4. 7.4.4 Supply and Ground
      5. 7.4.5 Device Enable
  8. Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Output Filter Design
        2. 8.2.2.2 Inductor Selection
        3. 8.2.2.3 Capacitor Selection
          1. 8.2.2.3.1 Input Capacitor
          2. 8.2.2.3.2 Output Capacitor
        4. 8.2.2.4 Setting The Output Voltage
      3. 8.2.3 Application Curves
  9. Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Related Links
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information
  13. 13Mechanical, Packaging, and Orderable Information

Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality.

Application Information

The TPS63024x are high efficiency, low quiescent current buck-boost converters suitable for application where the input voltage is higher, lower or equal to the output. Output currents can go as high as 1.5A in boost mode and as high as 3A in buck mode. The maximum average current in the switches is limited to a typical value of 3A.

Typical Application

TPS63024 TPS630241 TPS630242 schematic11.gif Figure 7. 3.3-V Adjustable Version

Design Requirements

The design guideline provides a component selection to operate the device within the recommended operating conditions.

Table 1 shows the list of components for the Application Characteristic Curves.

Table 1. Components for Application Characteristic Curves(1)

REFERENCE DESCRIPTION MANUFACTURER
TPS63024 Texas Instruments
L1 1 μH, 8.75A, 13mΩ, SMD XAL4020-102MEB, Coilcraft
C1 10 μF 6.3V, 0603, X5R ceramic Standard
C2,C3 22 μF 6.3V, 0603, X5R ceramic Standard
R1 560kΩ Standard
R2 180kΩ Standard

Detailed Design Procedure

The first step is the selection of the output filter components. To simplify this process Table 2 outline possible inductor and capacitor value combinations.

Output Filter Design

Table 2. Matrix of Output Capacitor and Inductor Combinations

NOMINAL INDUCTOR
VALUE [µH](1)
NOMINAL OUTPUT CAPACITOR VALUE [µF](2)
44 47 66 88 100
0.680 + + +
1.0 +(3) + + + +
1.5 + + +
Inductor tolerance and current de-rating is anticipated. The effective inductance can vary by 20% and –30%.
Capacitance tolerance and bias voltage de-rating is anticipated. The effective capacitance can vary by 20% and –50%.
Typical application. Other check mark indicates recommended filter combinations

Inductor Selection

The inductor selection is affected by several parameter like inductor ripple current, output voltage ripple, transition point into Power Save Mode, and efficiency. See Table 3 for typical inductors.

Table 3. List of Recommended Inductors(1)

INDUCTOR VALUE COMPONENT SUPPLIER SIZE (LxWxH mm) Isat/DCR
1 µH Coilcraft XAL4020-102ME 4 X 4 X 2.10 4.5A/10mΩ
1 µH Toko, DFE322512C 3.2 X 2.5 X 1.2 4.7A/34mΩ
1 µH TDK, SPM4012 4.4 X 4.1 X 1.2 4.1A/38mΩ
1 µH Wuerth, 74438334010 3 X 3 X 1.2 6.6A/42.10mΩ
0.6 µH Coilcraft XFL4012-601ME 4 X 4 X 1.2 5A/17.40mΩ
0.68µH Wuerth,744383340068 3 X 3 X 1.2 7.7A/36mΩ

For high efficiencies, the inductor should have a low dc resistance to minimize conduction losses. Especially at high-switching frequencies, the core material has a high impact on efficiency. When using small chip inductors, the efficiency is reduced mainly due to higher inductor core losses. This needs to be considered when selecting the appropriate inductor. The inductor value determines the inductor ripple current. The larger the inductor value, the smaller the inductor ripple current and the lower the conduction losses of the converter. Conversely, larger inductor values cause a slower load transient response. To avoid saturation of the inductor, the peak current for the inductor in steady state operation is calculated using Equation 6. Only the equation which defines the switch current in boost mode is shown, because this provides the highest value of current and represents the critical current value for selecting the right inductor.

Equation 5. TPS63024 TPS630241 TPS630242 q1_boost_lvsa92.gif
Equation 6. TPS63024 TPS630241 TPS630242 peak_current_boost_lvsa92.gif

where

  • D =Duty Cycle in Boost mod
  • ƒ = Converter switching frequency (typical 2.5MHz)
  • L = Inductor value
  • η = Estimated converter efficiency (use the number from the efficiency curves or 0.90 as an assumption)
  • Note: The calculation must be done for the minimum input voltage which is possible to have in boost mode

Calculating the maximum inductor current using the actual operating conditions gives the minimum saturation current of the inductor needed. It's recommended to choose an inductor with a saturation current 20% higher than the value calculated using Equation 6. Possible inductors are listed in Table 3.

Capacitor Selection

Input Capacitor

At least a 10μF input capacitor is recommended to improve line transient behavior of the regulator and EMI behavior of the total power supply circuit. An X5R or X7R ceramic capacitor placed as close as possible to the VIN and PGND pins of the IC is recommended. This capacitance can be increased without limit. If the input supply is located more than a few inches from the TPS63024x converter additional bulk capacitance may be required in addition to the ceramic bypass capacitors. An electrolytic or tantalum capacitor with a value of 47 μF is a typical choice.

Output Capacitor

For the output capacitor, use of a small ceramic capacitors placed as close as possible to the VOUT and PGND pins of the IC is recommended. The recommended nominal output capacitance value is 20 µF with a variance as outlined in Table 2.

There is also no upper limit for the output capacitance value. Larger capacitors causes lower output voltage ripple as well as lower output voltage drop during load transients.

Setting The Output Voltage

When the adjustable output voltage version TPS63024x is used, the output voltage is set by an external resistor divider. The resistor divider must be connected between VOUT, FB and GND. When the output voltage is regulated properly, the typical value of the voltage at the FB pin is 800mV. The current through the resistive divider should be about 10 times greater than the current into the FB pin. The typical current into the FB pin is 0.1μA, and the voltage across the resistor between FB and GND, R2, is typically 800 mV. Based on these two values, the recommended value for R2 should be lower than 180kΩ, in order to set the divider current at 4μA or higher. It is recommended to keep the value for this resistor in the range of 180kΩ. From that, the value of the resistor connected between VOUT and FB, R1, depending on the needed output voltage (VOUT), can be calculated using Equation 7:

Equation 7. TPS63024 TPS630241 TPS630242 qr1r2_lvs916.gif

Application Curves

TPS63024 TPS630241 TPS630242 MaxCurrent3_SLVSCK8.gif
VOUT = 3.3 V
Figure 8. Minimum Average Input Current vs Input Voltage
TPS63024 TPS630241 TPS630242 Figure3rev1_SLVSCK8.gif
PFM/PWM = High
Figure 10. Efficiency vs Output Current
TPS63024 TPS630241 TPS630242 Figure2rev1_SLVSCK8.gif
PFM/PWM = Low
Figure 9. Efficiency vs Output Current
TPS63024 TPS630241 TPS630242 Figure4rev1_SLVSCK8.gif
PFM/PWM = Low
Figure 11. Efficiency vs Output Current
TPS63024 TPS630241 TPS630242 Figure6rev2_SLVSCK8.gif
PFM/PWM = Low VOUT = 3.3 V
Figure 13. Efficiency vs Input Voltage
TPS63024 TPS630241 TPS630242 Figure5rev1_SLVSCK8.gif
PFM/PWM = High
Figure 12. Efficiency vs Output Current
TPS63024 TPS630241 TPS630242 Figure7rev1_SLVSCK8.gif
PFM/PWM = High VOUT = 3.3 V
Figure 14. Efficiency vs Input Voltage
TPS63024 TPS630241 TPS630242 Figure8rev1_SLVSCK8.gif
PFM/PWM = Low VOUT = 2.9 V
Figure 15. Efficiency vs Input Voltage
TPS63024 TPS630241 TPS630242 Figure19rev24_SLVSCK8.gif
PFM/PWM = Low
Figure 17. Output Voltage vs Output Current
TPS63024 TPS630241 TPS630242 Figure14_SLVSCK8.gif
VIN = 3.3 V IOUT = 290 mA
Figure 19. Output Voltage Ripple in Buck-Boost Mode
and PFM to PWM Transition
TPS63024 TPS630241 TPS630242 Figure9rev1_SLVSCK8.gif
PFM/PWM = High VOUT = 2.9 V
Figure 16. Efficiency vs Input Voltage
TPS63024 TPS630241 TPS630242 Figure20rev4_SLVSCK8.gif
PFM/PWM = High
Figure 18. Output Voltage vs Output Current
TPS63024 TPS630241 TPS630242 Figure15_SLVSCK8.gif
VIN = 2.8 V IOUT = 16 mA
Figure 20. Output Voltage Ripple in Boost Mode and PFM Operation
TPS63024 TPS630241 TPS630242 Figure16_SLVSCK8.gif
VIN = 4.2 V IOUT = 16 mA
Figure 21. Output Voltage Ripple in Buck Mode
and PFM Operation
TPS63024 TPS630241 TPS630242 Figure18rev1_SLVSCK8.gif
VIN = 4.5 V IOUT = 1 A
Figure 23. Switching Waveforms in Buck Mode
and PWM Operation
TPS63024 TPS630241 TPS630242 Figure20rev1_SLVSCK8.gif
VIN = 2.8 V IOUT = 0 A to 1.5 A
Figure 25. Load Transient Response Boost Mode
TPS63024 TPS630241 TPS630242 Figure22_SLVSCK8.gif
VIN = from 3.5 V to 3.6 V IOUT = 1.5 A
Figure 27. Line Transient Response
TPS63024 TPS630241 TPS630242 Figure24_SLVSCK8.gif
VIN = 4.5 V IOUT = 0 A
Figure 29. Start Up After Enable
TPS63024 TPS630241 TPS630242 Figure17_SLVSCK8.gif
VIN = 2.5 V IOUT = 1 A
Figure 22. Switching Waveforms in Boost Mode
and PWM Operation
TPS63024 TPS630241 TPS630242 Figure19_SLVSCK8.gif
VIN = 3.3 V IOUT = 1 A
Figure 24. Switching Waveforms in Buck-Boost Mode
and PWM Operation
TPS63024 TPS630241 TPS630242 Figure21_SLVSCK8.gif
VIN = 4.2 V IOUT = 0 A to 1.5 A
Figure 26. Load Transient Response Buck Mode
TPS63024 TPS630241 TPS630242 Figure23_SLVSCK8.gif
VIN = 2.5 V IOUT = 0 A
Figure 28. Start Up After Enable