SLVS762C June   2007  – July 2015 TPS62240 , TPS62242 , TPS62243


  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Device Options
  6. Pin Configuration and Functions
  7. Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Typical Characteristics
  8. Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Undervoltage Lockout
      2. 8.3.2 Mode Selection
      3. 8.3.3 Enable
      4. 8.3.4 Thermal Shutdown
    4. 8.4 Device Functional Modes
      1. 8.4.1 Soft Start
      2. 8.4.2 Power Save Mode
      3. 8.4.3 100% Duty Cycle Low Dropout Operation
      4. 8.4.4 Short-Circuit Protection
  9. Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. Output Voltage Setting
        2. Output Filter Design (Inductor and Output Capacitor)
          1. Inductor Selection
          2. Output Capacitor Selection
          3. Input Capacitor Selection
      3. 9.2.3 Application Curves
    3. 9.3 System Examples
      1. 9.3.1 TPS62240, Adjustable Output Voltage 1.8 V
      2. 9.3.2 TPS62243, Fixed Output Voltage 1.8 V
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Examples
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Third-Party Products Disclaimer
    2. 12.2 Related Links
    3. 12.3 Community Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

9 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.

9.1 Application Information

The TPS6224x device is a high-efficiency synchronous step-down DC-DC converter featuring power save mode or 2.25-MHz fixed-frequency operation.

9.2 Typical Application

TPS62240 TPS62242 TPS62243 adj_12_ai_lvs762.gifFigure 6. TPS62240DRV Adjustable 1.2 V

9.2.1 Design Requirements

The device operates over an input voltage range from 2 V to 6 V. The output voltage is adjustable using an external feedback divider.

9.2.2 Detailed Design Procedure

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

Table 1. List of Components

CIN GRM188R60J475K Murata 4.7 μF, 6.3 V. X5R Ceramic
COUT GRM188R60J106M Murata 10 μF, 6.3 V. X5R Ceramic
C1 Murata 22 pF, COG Ceramic
L1 LPS3015 Coilcraft 2.2 μH, 110 mΩ
R1, R2 Values depending on the programmed output voltage Output Voltage Setting

The output voltage can be calculated to:

Equation 2. TPS62240 TPS62242 TPS62243 inl1_vout_lvs762.gif with an internal reference voltage VREF typical 0.6 V.

To minimize the current through the feedback divider network, R2 should be 180 kΩ or 360 kΩ. The sum of R1 and R2 should not exceed approximately 1 MΩ, to keep the network robust against noise.

An external feedforward capacitor C1 is required for optimum load transient response. The value of C1 should be in the range from 22 pF to 33 pF.

Route the FB line away from noise sources, such as the inductor or the SW line. Output Filter Design (Inductor and Output Capacitor)

The TPS6224x is designed to operate with inductors in the range of 1.5 μH to 4.7 μH and with output capacitors in the range of 4.7 μF to 22 μF. The device is optimized for operation with a 2.2-μH inductor and 10-μF output capacitor.

Larger or smaller inductor values can be used to optimize the performance of the device for specific operation conditions. For stable operation, the L and C values of the output filter may not fall below 1-μH effective inductance and 3.5-μF effective capacitance. Selecting larger capacitors is less critical because the corner frequency of the L-C filter moves to lower frequencies with fewer stability problems. Inductor Selection

The inductor value has a direct effect on the ripple current. The selected inductor must be rated for its DC resistance and saturation current. The inductor ripple current (ΔIL) decreases with higher inductance and increases with higher VIN or VOUT.

The inductor selection also has an impact on the output voltage ripple in the PFM mode. Higher inductor values will lead to lower output voltage ripple and higher PFM frequency, and lower inductor values will lead to a higher output voltage ripple but lower PFM frequency.

Equation 3 calculates the maximum inductor current in PWM mode under static load conditions. The saturation current of the inductor should be rated higher than the maximum inductor current as calculated with Equation 4. This is recommended because during heavy load transients the inductor current will rise above the calculated value.

Equation 3. TPS62240 TPS62242 TPS62243 q3_delta_lvs762_.gif
Equation 4. TPS62240 TPS62242 TPS62243 q4_ilmax_lvs762.gif


  • f = Switching frequency (2.25-MHz typical)
  • L = Inductor value
  • ΔIL = Peak-to-peak inductor ripple current
  • ILmax = Maximum inductor current

A more conservative approach is to select the inductor current rating just for the maximum switch current limit ILIMF of the converter.

Accepting larger values of ripple current allows the use of low inductance values, but results in higher output voltage ripple, greater core losses, and lower output current capability.

The total losses of the coil have a strong impact on the efficiency of the DC-DC conversion and consist of both the losses in the DC resistance (R(DC)) and the following frequency-dependent components:

  • The losses in the core material (magnetic hysteresis loss, especially at high switching frequencies)
  • Additional losses in the conductor from the skin effect (current displacement at high frequencies)
  • Magnetic field losses of the neighboring windings (proximity effect)
  • Radiation losses

Table 2. List of Inductors

2.5 × 2 × 1 2 MIPS2520D2R2 FDK
2.5 × 2 × 1.2 2 MIPSA2520D2R2 FDK
2.5 × 2 × 1 2.2 KSLI-252010AG2R2 Hitachi Metals
2.5 × 2 × 1.2 2.2 LQM2HPN2R2MJ0L Murata
3 × 3 × 1.4 2.2 LPS3015 Coilcraft Output Capacitor Selection

The advanced fast-response voltage mode control scheme of the TPS6224x allows the use of tiny ceramic capacitors. Ceramic capacitors with low ESR values have the lowest output voltage ripple and are recommended. The output capacitor requires either an X7R or X5R dielectric. Y5V and Z5U dielectric capacitors, aside from their wide variation in capacitance overtemperature, become resistive at high frequencies.

At nominal load current, the device operates in PWM mode and the RMS ripple current is calculated as:

Equation 5. TPS62240 TPS62242 TPS62243 q5_irmsc_lvs762.gif

At nominal load current, the device operates in PWM mode and the overall output voltage ripple is the sum of the voltage spike caused by the output capacitor ESR plus the voltage ripple caused by charging and discharging the output capacitor:

Equation 6. TPS62240 TPS62242 TPS62243 q6_deltav_lvs762.gif

At light load currents, the converter operates in power save mode and the output voltage ripple depends on the output capacitor and inductor value. Larger output capacitor and inductor values minimize the voltage ripple in PFM mode and tighten DC output accuracy in PFM mode. Input Capacitor Selection

The buck converter has a natural pulsating input current; therefore, a low ESR input capacitor is required for best input voltage filtering, and minimizing the interference with other circuits caused by high input voltage spikes. For most applications, a 4.7-μF to 10-μF ceramic capacitor is recommended. Because ceramic capacitors lose up to 80% of their initial capacitance at 5 V, it is recommended that a 10-μF input capacitor be used for input voltages greater than 4.5 V. The input capacitor can be increased without any limit for better input voltage filtering.

Take care when using only small ceramic input capacitors. When a ceramic capacitor is used at the input, and the power is being supplied through long wires, such as from a wall adapter, a load step at the output, or VIN step on the input, can induce ringing at the VIN pin. The ringing can couple to the output and be mistaken as loop instability, or could even damage the part by exceeding the maximum ratings

Table 3. List of Capacitors

4.7 μF GRM188R60J475K 0603: 1.6 × 0.8 × 0.8 mm3 Murata
10 μF GRM188R60J106M69D 0603: 1.6 × 0.8 × 0.8 mm3 Murata

9.2.3 Application Curves

TPS62240 TPS62242 TPS62243 effic_io_lvs762.gifFigure 7. Efficiency (Power Save Mode) vs Output Current
TPS62240 TPS62242 TPS62243 eff_12v_vin_lvs762.gifFigure 9. Efficiency vs Output Current
TPS62240 TPS62242 TPS62243 voacc1_io_lvs762.gifFigure 11. Output Voltage Accuracy vs Output Current
TPS62240 TPS62242 TPS62243 voacc3_io_lvs762.gifFigure 13. Output Voltage Accuracy vs Output Current
TPS62240 TPS62242 TPS62243 voacc5_io_lvs762.gifFigure 15. Output Voltage Accuracy vs Output Current
TPS62240 TPS62242 TPS62243 st_vo_18_lvs762.gifFigure 17. Start-Up Timing
TPS62240 TPS62242 TPS62243 top_pfm1_lvs762.gifFigure 19. Typical Operation vs PFM Mode
TPS62240 TPS62242 TPS62243 pfm_ltr1_lvs762.gifFigure 21. PFM Load Transient
TPS62240 TPS62242 TPS62243 pfm_ltr50_lvs762.gifFigure 23. PFM Load Transient
TPS62240 TPS62242 TPS62243 litr_pfm_25_lvs762.gifFigure 25. PFM Line Transient
TPS62240 TPS62242 TPS62243 tr_wm_fm_lvs762.gifFigure 27. Mode Transition PWM to PFM
TPS62240 TPS62242 TPS62243 eff2_io_lvs762.gifFigure 8. Efficiency (Forced PWM Mode) vs Output Current
TPS62240 TPS62242 TPS62243 eff_12v_gnd_lvs762.gifFigure 10. Efficiency vs Output Current
TPS62240 TPS62242 TPS62243 voacc2_io_lvs762.gifFigure 12. Output Voltage Accuracy vs Output Current
TPS62240 TPS62242 TPS62243 voacc4_io_lvs762.gifFigure 14. Output Voltage Accuracy vs Output Current
TPS62240 TPS62242 TPS62243 voacc6_io_lvs762.gifFigure 16. Output Voltage Accuracy vs Output Current
TPS62240 TPS62242 TPS62243 top_pwm1_lvs762.gifFigure 18. Typical Operation vs PWM Mode
TPS62240 TPS62242 TPS62243 pfmripp_18_lvs762.gifFigure 20. PFM Mode Ripple
TPS62240 TPS62242 TPS62243 pfm_ltr20_lvs762.gifFigure 22. PFM Load Transient
TPS62240 TPS62242 TPS62243 litr_pfm_5_lvs762.gifFigure 24. PFM Line Transient
TPS62240 TPS62242 TPS62243 tr_fm_wm_lvs762.gifFigure 26. Mode Transition PFM to PWM

9.3 System Examples

9.3.1 TPS62240, Adjustable Output Voltage 1.8 V

TPS62240 TPS62242 TPS62243 adj_18_ai_lvs762.gifFigure 28. TPS62240DRV 1.8 V

9.3.2 TPS62243, Fixed Output Voltage 1.8 V

TPS62240 TPS62242 TPS62243 ai4_fix18_lvs762.gifFigure 29. TPS62243 Fixed 1.8 V