SLVS510E July   2006  – March 2015 TPS61070 , TPS61071 , TPS61072 , TPS61073


  1. Features
  2. Applications
  3. Description
  4. Typical Application Circuit
  5. Revision History
  6. Device Comparison Table
  7. Pin Configuration and Functions
  8. Specifications
    1. 8.1 Absolute Maximum Ratings
    2. 8.2 ESD Ratings
    3. 8.3 Recommended Operating Conditions
    4. 8.4 Thermal Information
    5. 8.5 Electrical Characteristics
    6. 8.6 Typical Characteristics
      1. 8.6.1 Table of Graphs
  9. Parameter Measurement Information
  10. 10Detailed Description
    1. 10.1 Overview
    2. 10.2 Functional Block Diagram
    3. 10.3 Feature Description
      1. 10.3.1 Controller Circuit
        1. Synchronous Rectifier
        2. Device Enable
        3. Undervoltage Lockout
        4. Soft Start and Short-Circuit Protection
    4. 10.4 Device Functional Modes
      1. 10.4.1 Power-Save Mode
  11. 11Application and Implementation
    1. 11.1 Application Information
    2. 11.2 Typical Application
      1. 11.2.1 Design Requirements
      2. 11.2.2 Detailed Design Procedure
        1. Programming the Output Voltage
        2. Inductor Selection
        3. Capacitor Selection
          1. Input Capacitor
          2. Output Capacitor
        4. Small Signal Stability
      3. 11.2.3 Application Curves
    3. 11.3 System Examples
  12. 12Power Supply Recommendations
  13. 13Layout
    1. 13.1 Layout Guidelines
    2. 13.2 Layout Example
    3. 13.3 Thermal Considerations
  14. 14Device and Documentation Support
    1. 14.1 Device Support
      1. 14.1.1 Third-Party Products Disclaimer
    2. 14.2 Related Links
    3. 14.3 Trademarks
    4. 14.4 Electrostatic Discharge Caution
    5. 14.5 Glossary
  15. 15Mechanical, Packaging, and Orderable Information

Package Options

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • DDC|6
Thermal pad, mechanical data (Package|Pins)
Orderable Information

11 Application and Implementation


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.

11.1 Application Information

The TPS6107x DC-DC converters are intended for systems powered by a single-cell, up to triple-cell alkaline, NiCd, NiMH battery with a typical terminal voltage between 0.9 V and 5.5 V. They can also be used in systems powered by one-cell Li-Ion or Li-Polymer with a typical voltage between 2.5 V and 4.2 V. Additionally, any other voltage source with a typical output voltage between 0.9 V and 5.5 V can power systems where the TPS6107x is used. Due to the nature of boost converters, the output voltage regulation is only maintained when the input voltage applied is lower than the programmed output voltage.

11.2 Typical Application

TPS61070 TPS61071 TPS61072 TPS61073 ai_typ_app_lvs510.gifFigure 12. Typical Application Circuit for Adjustable Output Voltage Option

11.2.1 Design Requirements

In this example, TPS61070 is used to design a 3.3-V power supply with 75-mA output current capability. The TPS61200 can be powered by either a single-cell, two-cell, or three-cell alkaline, NiCd or NiMH, or one-cell Li-Ion or Li-Polymer battery. In this example, the input voltage range is from 0.9 V to 1.65 V for single-cell alkaline input design.

11.2.2 Detailed Design Procedure Programming the Output Voltage

The output voltage of the TPS6107x dc/dc converter can be adjusted with an external resistor divider. The typical value of the voltage at the FB pin is 500 mV. The maximum recommended value for the output voltage is 5.5 V. The current through the resistive divider should be about 100 times greater than the current into the FB pin. The typical current into the FB pin is 0.01 µA, and the voltage across R2 is typically 500 mV. Based on those two values, the recommended value for R2 should be lower than 500 kΩ, in order to set the divider current at 1 µA or higher. Because of internal compensation circuitry, the value for this resistor should be in the range of 200 kΩ. From that, the value of resistor R1, depending on the needed output voltage (VO), is calculated using Equation 1:

Equation 1. TPS61070 TPS61071 TPS61072 TPS61073 q_r3_lvs510.gif

For example, if an output voltage of 3.3 V is needed, a 1 MΩ resistor should be chosen for R1. If for any reason the value chosen for R2 is significantly lower than 200 kΩ, additional capacitance in parallel to R1 is recommended, if the device shows instable regulation of the output voltage. The required capacitance value is calculated using Equation 2:

Equation 2. TPS61070 TPS61071 TPS61072 TPS61073 q_cparr3_lvs510.gif Inductor Selection

A boost converter normally requires two main passive components for storing energy during the conversion. A boost inductor and a storage capacitor at the output are required. To select the boost inductor, it is recommended to keep the possible peak inductor current below the current limit threshold of the power switch in the chosen configuration. For example, the current limit threshold of the TPS6107x's switch is 600 mA. The highest peak current through the inductor and the switch depends on the output load, the input (VBAT), and the output voltage (VOUT). Estimation of the maximum average inductor current is done using Equation 3:

Equation 3. TPS61070 TPS61071 TPS61072 TPS61073 q_il_lvs510.gif

For example, for an output current of 75 mA at 3.3 V, at least 340 mA of average current flows through the inductor at a minimum input voltage of 0.9 V.

The second parameter for choosing the inductor is the desired current ripple in the inductor. Normally, it is advisable to work with a ripple of less than 20% of the average inductor current. A smaller ripple reduces the magnetic hysteresis losses in the inductor, as well as output voltage ripple and EMI. But in the same way, regulation time rises at load changes. In addition, a larger inductor increases the total system costs. With these parameters, it is possible to calculate the value for the inductor by using Equation 4:

Equation 4. TPS61070 TPS61071 TPS61072 TPS61073 q_l_lvs510.gif

Parameter f is the switching frequency and ΔIL is the ripple current in the inductor, i.e., 40% ΔIL. In this example, the desired inductor has the value of 4 µH. With this calculated value and the calculated currents, it is possible to choose a suitable inductor. In typical applications, a 4.7-µH inductance is recommended. The device has been optimized to operate with inductance values between 2.2 µH and 10 µH. Nevertheless, operation with higher inductance values may be possible in some applications. Detailed stability analysis is then recommended. Care must be taken because load transients and losses in the circuit can lead to higher currents as estimated in Equation 4. Also, the losses in the inductor caused by magnetic hysteresis losses and copper losses are a major parameter for total circuit efficiency.

The following inductor series from different suppliers have been used with the TPS6107x converters:

Table 1. List of Inductors

Wurth Elektronik 744031xxx
EPCOS B82462-G4
Cooper Electronics Technologies SD18
Taiyo Yuden CB2016B xxx
CB2518B xxx Capacitor Selection Input Capacitor

At least a 10 µF input capacitor is recommended to improve transient behavior of the regulator and EMI behavior of the total power supply circuit. A ceramic capacitor or a tantalum capacitor with a 100-nF ceramic capacitor in parallel, placed close to the IC, is recommended. Output Capacitor

The major parameter necessary to define the output capacitor is the maximum allowed output voltage ripple of the converter. This ripple is determined by two parameters of the capacitor, the capacitance and the ESR. It is possible to calculate the minimum capacitance needed for the defined ripple, supposing that the ESR is zero, by using Equation 5:

Equation 5. TPS61070 TPS61071 TPS61072 TPS61073 q_cmin_lvs510.gif

Parameter f is the switching frequency and ΔV is the maximum allowed ripple.

With a chosen ripple voltage of 10 mV, a minimum capacitance of 4.5 µF is needed. In this value range, ceramic capacitors are a good choice. The ESR and the additional ripple created are negligible. It is calculated using Equation 6:

Equation 6. TPS61070 TPS61071 TPS61072 TPS61073 q_vesr_lvs510.gif

The total ripple is the sum of the ripple caused by the capacitance and the ripple caused by the ESR of the capacitor. Additional ripple is caused by load transients. This means that the output capacitor has to completely supply the load during the charging phase of the inductor. The value of the output capacitance depends on the speed of the load transients and the load current during the load change. With the calculated minimum value of 4.5 µF and load transient considerations, the recommended output capacitance value is in a 10 µF range.

Care must be taken on capacitance loss caused by derating due to the applied dc voltage and the frequency characteristic of the capacitor. For example, larger form factor capacitors (in 1206 size) have their self resonant frequencies in the same frequency range as the TPS6107x operating frequency. So the effective capacitance of the capacitors used may be significantly lower. Therefore, the recommendation is to use smaller capacitors in parallel instead of one larger capacitor. Small Signal Stability

To analyze small signal stability in more detail, the small signal transfer function of the error amplifier and the regulator, which is given in Equation 7, can be used:

Equation 7. TPS61070 TPS61071 TPS61072 TPS61073 q_areg_lvs510.gif

11.2.3 Application Curves

Output voltage in continuous mode (TPS61071) Figure 13
Output voltage in continuous mode (TPS61071) Figure 14
Output voltage in power-save mode (TPS61070) Figure 15
Output voltage in power-save mode (TPS61070) Figure 16
Load transient response (TPS61071) Figure 17
Load transient response (TPS61071) Figure 18
Line transient response (TPS61071) Figure 19
Line transient response (TPS61071) Figure 20
Start-up after enable (TPS61070) Figure 21
Start-up after enable (TPS61070) Figure 22
Start-up after enable (TPS61071) Figure 23
Start-up after enable (TPS61071) Figure 24
TPS61070 TPS61071 TPS61072 TPS61073 vo_33_cont_lvs510.gifFigure 13. TPS61071 Output Voltage in Continuous Mode
TPS61070 TPS61071 TPS61072 TPS61073 vo_33v_psm_lvs510.gifFigure 15. TPS61070 Output Voltage in Power-Save Mode
TPS61070 TPS61071 TPS61072 TPS61073 load33v_plot_lvs510.gifFigure 17. TPS61071 Load Transient Response
TPS61070 TPS61071 TPS61072 TPS61073 line33v_plot_lvs510.gifFigure 19. TPS61071 Line Transient Response
TPS61070 TPS61071 TPS61072 TPS61073 start33v_70_lvs510.gifFigure 21. TPS61070 Start-Up After Enable
TPS61070 TPS61071 TPS61072 TPS61073 strup_33v_71_lvs510.gifFigure 23. TPS61071 Start-Up After Enable
TPS61070 TPS61071 TPS61072 TPS61073 vo_50_cont_lvs510.gifFigure 14. TPS61071 Output Voltage In Continuous Mode
TPS61070 TPS61071 TPS61072 TPS61073 vo_50v_psm_lvs510.gifFigure 16. TPS61070 Output Voltage in Power-Save Mode
TPS61070 TPS61071 TPS61072 TPS61073 load50v_plot_lvs510.gifFigure 18. TPS61071 Load Transient Response
TPS61070 TPS61071 TPS61072 TPS61073 line50v_plot_lvs510.gifFigure 20. TPS61071 Line Transient Response
TPS61070 TPS61071 TPS61072 TPS61073 start50v_70_lvs510.gifFigure 22. TPS61070 Start-Up After Enable
TPS61070 TPS61071 TPS61072 TPS61073 strup_50v_71_lvs510.gifFigure 24. TPS61071 Start-Up After Enable

11.3 System Examples

TPS61070 TPS61071 TPS61072 TPS61073 ai_alka_cell_lvs510.gifFigure 25. Power Supply Solution for Maximum Output Power Operating from a Single or
Dual Alkaline Cell
TPS61070 TPS61071 TPS61072 TPS61073 ai_sts_size_lvs501.gifFigure 26. Power Supply Solution Having Small Total Solution Size
TPS61070 TPS61071 TPS61072 TPS61073 ai_white_led_lvs510.gifFigure 27. Power Supply Solution for Powering White LEDs in Lighting Applications
TPS61070 TPS61071 TPS61072 TPS61073 pwr_sup_pout_lvs510.gifFigure 28. Power Supply Solution With Auxiliary Positive Output Voltage
TPS61070 TPS61071 TPS61072 TPS61073 pwr_spl_nout_lvs510.gifFigure 29. Power Supply Solution With Auxiliary Negative Output Voltage