SLUS534G September   2002  – March 2015 TPS61030 , TPS61031 , TPS61032

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Simplified Schematic
  5. 5 Revision History
  6. 6 Device Comparison Table
  7. 7 Pin Configuration and Functions
  8. 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
  9. 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
      2. 10.3.2 Synchronous Rectifier
    4. 10.4 Device Functional Modes
      1. 10.4.1 Device Enable
        1. 10.4.1.1 Undervoltage Lockout
      2. 10.4.2 Softstart
      3. 10.4.3 Power Save Mode And Synchronization
      4. 10.4.4 Low Battery Detector Circuit—LBI/LBO
      5. 10.4.5 Low-EMI Switch
  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. 11.2.2.1 Programming The Output Voltage
        2. 11.2.2.2 Programming The LBI/LBO Threshold Voltage
        3. 11.2.2.3 Inductor Selection
        4. 11.2.2.4 Capacitor Selection
          1. 11.2.2.4.1 Input Capacitor
          2. 11.2.2.4.2 Output Capacitor
            1. 11.2.2.4.2.1 Small Signal Stability
      3. 11.2.3 Application Curves
      4. 11.2.4 System Examples
        1. 11.2.4.1 Power Supply Solution For Maximum Output Power
        2. 11.2.4.2 Power Supply Solution With Auxiliary Positive Output Voltage
        3. 11.2.4.3 Power Supply Solution with Auxiliary Negative Output Voltage
  12. 12Power Supply Recommendations
  13. 13Layout
    1. 13.1 Layout Considerations
    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

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11 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.

11.1 Application Information

The TPS6103x dc/dc converters are intended for systems powered by a dual or triple cell NiCd or NiMH battery with a typical terminal voltage between 1.8 V and 5.5 V. They can also be used in systems powered by one-cell Li-Ion with a typical stack voltage between 2.5 V and 4.2 V. Additionally, two or three primary and secondary alkaline battery cells can be the power source in systems where the TPS6103x is used.

11.2 Typical Application

TPS61030 TPS61031 TPS61032 ai_typ_app_LUS534.gifFigure 13. Typical Application Circuit For Adjustable Output Voltage Option

11.2.1 Design Requirements

Use the following typical application design procedure to select external components values for the TPS61030 device.

Table 2. TPS61030 5 V Output Design Parameters

DESIGN PARAMETERS EXAMPLE VALUES
Input Voltage Range 1.8 V to 5.5 V
Output Voltage 5.0 V
Output Voltage Ripple +/- 3% VOUT
Transient Response +/- 10% VOUT
Input Voltage Ripple +/- 200mV
Output Current 2A
Operating Frequency 600 kHz

11.2.2 Detailed Design Procedure

11.2.2.1 Programming The Output Voltage

The output voltage of the TPS61030 dc/dc converter section can be adjusted with an external resistor divider. The typical value of the voltage on the FB pin is 500 mV. The maximum allowed 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 R6 is typically 500 mV. Based on those two values, the recommended value for R4 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 R3, depending on the needed output voltage (VO), can be calculated using equation 1:

Equation 1. TPS61030 TPS61031 TPS61032 Q_R3_LUS534.gif

If as an example, an output voltage of 3.3 V is needed, a 1-MΩ resistor should be chosen for R3. If for any reason the value for R4 is chosen significantly lower than 200 kΩ additional capacitance in parallel to R3 is recommended. The required capacitance value can be easily calculated using Equation 2:

Equation 2. TPS61030 TPS61031 TPS61032 q_cparr3_lvs484.gif

11.2.2.2 Programming The LBI/LBO Threshold Voltage

The current through the resistive divider should be about 100 times greater than the current into the LBI pin. The typical current into the LBI pin is 0.01 µA, and the voltage across R2 is equal to the LBI voltage threshold that is generated on-chip, which has a value of 500 mV. The recommended value for R2 is therefore in the range of 500 kΩ. From that, the value of resistor R1, depending on the desired minimum battery voltage VBAT, can be calculated using Equation 3.

Equation 3. TPS61030 TPS61031 TPS61032 Q_R1_LUS534.gif

The output of the low battery supervisor is a simple open-drain output that goes active low if the dedicated battery voltage drops below the programmed threshold voltage on LBI. The output requires a pullup resistor with a recommended value of 1 MΩ. The maximum voltage which is used to pull up the LBO outputs should not exceed the output voltage of the dc/dc converter. If not used, the LBO pin can be left floating or tied to GND.

11.2.2.3 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 TPS6103x's switch is 4500 mA at an output voltage of 5 V. 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 can be done using Equation 4:

Equation 4. TPS61030 TPS61031 TPS61032 Q_IL_LUS534.gif

For example, for an output current of 1000 mA at 5 V, at least 3500 mA of average current flows through the inductor at a minimum input voltage of 1.8 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 at load changes rises. In addition, a larger inductor increases the total system costs. With those parameters, it is possible to calculate the value for the inductor by using Equation 5:

Equation 5. TPS61030 TPS61031 TPS61032 Q_L_LUS534.gif

Parameter f is the switching frequency and ΔIL is the ripple current in the inductor, i.e., 10% × IL. In this example, the desired inductor has the value of 5.5 µH. In typical applications a 6.8 µH inductance is recommended. The minimum possible inductance value is 2.2 µH. With the calculated inductance and current values, it is possible to choose a suitable inductor. Care has to be taken that 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 TPS6103x converters:

Table 3. List Of Inductors(1)

VENDOR INDUCTOR SERIES
Sumida CDRH124
CDRH103R
CDRH104R
Wurth Electronik 7447779___
744771___
EPCOS B82464G

11.2.2.4 Capacitor Selection

11.2.2.4.1 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.

11.2.2.4.2 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 6:

Equation 6. TPS61030 TPS61031 TPS61032 Q_CMIN_LUS534.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 100 µF is needed. The total ripple is larger due to the ESR of the output capacitor. This additional component of the ripple can be calculated using
Equation 7:

Equation 7. TPS61030 TPS61031 TPS61032 Q_VESR_LUS534.gif

An additional ripple of 80 mV is the result of using a tantalum capacitor with a low ESR of 80 mΩ. The total ripple is the sum of the ripple caused by the capacitance and the ripple caused by the ESR of the capacitor. In this example, the total ripple is 90 mV. Additional ripple is caused by load transients. This means that the output capacitance needs to be larger than calculated above to meet the total ripple requirements.

The output capacitor must completely supply the load during the charging phase of the inductor. A reasonable 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 100 µF and load transient considerations, a recommended output capacitance value is in around 220 µF. For economical reasons this usually is a tantalum capacitor. Because of this the control loop has been optimized for using output capacitors with an ESR of above 30 mΩ. The minimum value for the output capacitor is 22 µF.

11.2.2.4.2.1 Small Signal Stability

When using output capacitors with lower ESR, like ceramics, it is recommended to use the adjustable voltage version. The missing ESR can be easily compensated there in the feedback divider. Typically a capacitor in the range of 10 pF in parallel to R3 helps to obtain small signal stability with lowest ESR output capacitors. For more detailed analysis the small signal transfer function of the error amplifier and regulator, which is given in Equation 8, can be used.

Equation 8. TPS61030 TPS61031 TPS61032 q_areg_lus534.gif

11.2.3 Application Curves

TPS61030 TPS61031 TPS61032 VO_in_CM_LUS534.gif
VI = 3.3 V RL = 5 Ω
Figure 14. TPS61030 Output Voltage in Continuous Mode
TPS61030 TPS61031 TPS61032 Load_tran_LUS534.gif
VI = 2.5 V IL = 80 mA to 800 mA
Figure 16. TPS61030 Load Transient Response
TPS61030 TPS61031 TPS61032 Conv_startup_LUS534.gif
VI = 2.4 V RL = 20 Ω
Figure 18. TPS61030 DC/DC Converter Start-Up After Enable
TPS61030 TPS61031 TPS61032 VO_in_PSM_LUS534.gif
VI = 3.3 V RL = 100 Ω
Figure 15. TPS61030 Output Voltage in Power Save Mode
TPS61030 TPS61031 TPS61032 Line_tran_LUS534.gif
A.
VI = 2.2 V to 2.7 V RL = 50 Ω
Figure 17. TPS61030 Line Transient Response

11.2.4 System Examples

11.2.4.1 Power Supply Solution For Maximum Output Power

TPS61030 TPS61031 TPS61032 ai_PSS_Mout_LUS534.gifFigure 19. Power Supply Solution For Maximum Output Power

11.2.4.2 Power Supply Solution With Auxiliary Positive Output Voltage

TPS61030 TPS61031 TPS61032 ai_PSS_Pout_LUS534.gifFigure 20. Power Supply Solution With Auxiliary Positive Output Voltage

11.2.4.3 Power Supply Solution with Auxiliary Negative Output Voltage

TPS61030 TPS61031 TPS61032 ai_PSS_Nout_LUS534.gifFigure 21. Power Supply Solution With Auxiliary Negative Output Voltage