SLVSHD5 November   2024 TLV61047

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison Table
  6. 5 Pin Configuration and Functions
    1.     Pin 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 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 Undervoltage Lockout
      2. 7.3.2 Enable and Disable
      3. 7.3.3 Soft Start
      4. 7.3.4 Thermal Shutdown
    4. 7.4 Device Functional Modes
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 12V Output Boost Converter
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Programming the Output Voltage
          2. 8.2.1.2.2 Inductor Selection
          3. 8.2.1.2.3 Input and Output Capacitor Selection
          4. 8.2.1.2.4 Diode Rectifier Selection
        3. 8.2.1.3 Application Curves
      2. 8.2.2 28V Output Boost Converter
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Application Curves
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Device Support
      1. 9.1.1 Third-Party Products Disclaimer
    2. 9.2 Receiving Notification of Documentation Updates
    3. 9.3 Support Resources
    4. 9.4 Trademarks
    5. 9.5 Electrostatic Discharge Caution
    6. 9.6 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

Package Options

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

7.4 Device Functional Modes

The TLV61047 operates at a quasi-constant frequency pulse width modulation (PWM) under heavy to light load conditions. As the load current decreases, the output of the internal error amplifier also decreases to lower the inductor peak current and delivers less power. The PWM mode can be divided into CCM-PWM mode and DCM-PWM mode based on the load conditions.

  • The device operates in CCM-PWM mode with a heavy to moderate load. During this phase, the inductor current valley is always above zero.
  • The device operates in DCM-PWM mode as the load continues to decrease from moderate to light. As the name DCM (Discontinuous Current Mode) suggests, an obvious characteristic of this mode is that the inductor current remains at zero for one period in each cycle. During this phase, the inductor peak current can still be reduced by the output of the internal error amplifier to maintain the balance between input and output power. This allows a suitable off-time of the low-side FET to be worked out internally to keep the switching frequency quasi-constant without pulse skipping. This phase ends when the inductor peak current decreases to ICALMP_LOW, which is typically 20mA.
After the peak inductor current reaches the ICLAMP_LOW and the load decreases to ultra-light or even no load, the peak inductor current can't be smaller. To balance the input and output energy, the low-side FET is turned off for a prolonged period. The duration of the "zero inductor current" is much longer than in the DCM-PWM phase. This phase is called DCM-PFM mode for features of discontinuous inductor current and significantly reduced frequency. The three phases of CCM-PWM, DCM-PWM and DCM-PFM are shown in the Figure 7-1.

In work conditions where the VIN is very close to the VOUT, the VIN VOUT ratio decided turn on time may be less than the minimum turn on time, the device also enters into the DCM-PFM mode.

At light load, when TON min is triggered the device also enters DCM-PFM mode even if the inductor peak current is greater than ICALMP_LOW. When the low-side FET is turned on, it remains on for a minimum time, called TON min. The inductor is energised for at least TON min time when the low-side FET is on. If the TON min is greater than the ideal time required to maintain the quasi-constant frequency, the device has to extend the off time to balance the input and output energy. So the device is in DCM-PFM mode. Under normal work conditions, the TON min triggered DCM-PFM mode is much more common than that triggered by ICALMP_LOW, unless an inductor with extremely large inductance is used.

TLV61047 TLV61047 Functional Modes Figure 7-1 TLV61047 Functional Modes