SLVSHH0 June   2026 TPS61290

PRODMIX  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison Table
  6. 5 Pin Configuration and Functions
  7. 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 I2C Interface Timing Requirements
    7. 6.7 Typical Characteristics
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Output Voltage Setting
      2. 7.3.2 Switching Frequency and Spread Spectrum Function
    4. 7.4 Device Functional Modes
      1. 7.4.1  Enable and Start-Up
      2. 7.4.2  Operation Mode Setting
      3. 7.4.3  Bypass Mode
      4. 7.4.4  Boost Control Operation
      5. 7.4.5  Auto PFM Mode
      6. 7.4.6  Forced PWM Mode
      7. 7.4.7  Output Discharge
      8. 7.4.8  Undervoltage Lockout
      9. 7.4.9  Current Limit Operation
      10. 7.4.10 Output Short-to-Ground Protection
      11. 7.4.11 Thermal Shutdown
      12. 7.4.12 Power-Good Indication Status
    5. 7.5 Programming
      1. 7.5.1 Data Validity
      2. 7.5.2 START and STOP Conditions
      3. 7.5.3 Byte Format
      4. 7.5.4 Acknowledge (ACK) and Not Acknowledge (NACK)
      5. 7.5.5 Target Address and Data Direction Bit
      6. 7.5.6 Single Read and Write
      7. 7.5.7 Multi-Read and Multi-Write
  9. 8 Register Maps
    1. 8.1 DeviceID Register
    2. 8.2 CONFIG Register
    3. 8.3 VOUTFLOORSET Register
    4. 8.4 ILIMBSTSET Register
    5. 8.5 VOUTROOFSET Register
    6. 8.6 STATUS Register
    7. 8.7 ILIMPTSET Register
    8. 8.8 BSTLOOP Register
  10. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 TPS61290x With 2.5V – 4.35V VIN, 3.4V VOUT, 6A Output Current
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
          1. 9.2.1.2.1 Inductor Selection
          2. 9.2.1.2.2 Output Capacitor
          3. 9.2.1.2.3 Input Capacitor
          4. 9.2.1.2.4 Checking Loop Stability
        3. 9.2.1.3 Application Curves
      2. 9.2.2 TPS61290x With 2.5V – 4.85V VIN, 5.0V VOUT, 4A Output Current
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
        3. 9.2.2.3 Application Curves
    3. 9.3 Power Supply Recommendations
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
      2. 9.4.2 Layout Example
      3. 9.4.3 Thermal Information
  11. 10Device and Documentation Support
    1. 10.1 Device Support
      1. 10.1.1 Third-Party Products Disclaimer
    2. 10.2 Receiving Notification of Documentation Updates
    3. 10.3 Support Resources
    4. 10.4 Trademarks
    5. 10.5 Electrostatic Discharge Caution
    6. 10.6 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information
    1.     81

7.3.2 Switching Frequency and Spread Spectrum Function

The TPS61290x uses a hysteretic control scheme, and TPS61290x maintains a constant inductor ripple current in the range of 3.0A. Therefore, the frequency is not fixed and determined by the operation condition. The frequency is approximately 2MHz, when the input is 2.7V, output is 3.4V, inductor is 100nH.

In auto PFM operation, the minimum switching frequency is not limited, the switching frequency is approximately 20Hz (or even lower) with open load.

In forced PWM operation, minimum switching frequency is limited to approximately 375kHz. With this unique feature, the TPS61290x avoids the low frequency switching and prevents the application against the low frequency noise sensitive range.

Switching regulators are particularly troublesome in applications where electromagnetic interference (EMI) is a concern. Switching regulators operate on a cycle-by-cycle basis to transfer power to an output. In most cases, the frequency of operation is either fixed or regulated, based on the output load. This method of conversion creates large components of noise at the frequency of operation (fundamental) and multiples of the operating frequency (harmonics).

The TPS61290x provides a spread spectrum feature. The goal is to spread out the emitted RF energy over a larger frequency range so that the resulting EMI is similar to white noise. The result is a spectrum that is continuous and lower in peak amplitude, making complying with electromagnetic interference (EMI) standards and with the power supply ripple requirements in cellular and non-cellular wireless applications easier. Radio receivers are typically susceptible to narrowband noise that is focused on specific frequencies.

The spread spectrum architecture varies the switching frequency by ca. ±8% of the nominal switching frequency thereby significantly reducing the peak radiated and conducting noise on both the input and output supplies. The frequency dithering scheme is modulated with a triangle profile and a modulation frequency fm.

TPS61290 Spectrum of a Frequency Modulated Sin - Wave With Sinusoidal Variation in TimeFigure 7-1 Spectrum of a Frequency Modulated Sin - Wave With Sinusoidal Variation in Time
TPS61290 Spread Bands of Harmonics in Modulated Square Signals Spectrum illustrations and formulae (Figure 7-1 and Figure 7-2) copyright IEEE TRANSACTIONS ON ELECTROMAGNETIC COMPATIBILITY, VOL. 47, NO.3, AUGUST 2005.Figure 7-2 Spread Bands of Harmonics in Modulated Square Signals (1)

The above figures show that after modulation the sideband harmonic is attenuated compared to the non-modulated harmonic, and the harmonic energy is spread into a certain frequency band. The higher the modulation index (mf) the larger the attenuation.

Equation 1. mf=δ×fcfm

where

  • fc is the carrier frequency (switching frequency)
  • fm is the modulating frequency (approximately 0.5% × fc)
  • δ is the modulation ratio (approximately 8%)
Equation 2. δ=∆fcfc

The maximum switching frequency fc is limited by the process and finally the parameter modulation ratio (δ), together with fm, which is the side-band harmonics bandwidth around the carrier frequency fc. The bandwidth of a frequency modulated waveform is approximately given by the Carson’s rule and can be summarized as:

Equation 3. B=2×fm×1+mf=2×∆fc+fm

fm < RBW: The receiver is not able to distinguish individual side-band harmonics, so, several harmonics are added in the input filter and the measured value is higher than expected in theoretical calculations.

fm > RBW: The receiver is able to properly measure each individual side-band harmonic separately, so the measurements match with the theoretical calculations.

1. Spectrum illustrations and formulae (Figure 7-1 and Figure 7-2) copyright IEEE TRANSACTIONS ON ELECTROMAGNETIC COMPATIBILITY, VOL. 47, NO.3, AUGUST 2005.