SLVSAM7A March   2011  – May 2015 TLV61224

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 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
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Controller Circuit
      2. 7.3.2 Start-up
      3. 7.3.3 Operation at Output Overload
      4. 7.3.4 Undervoltage Lockout
      5. 7.3.5 Overvoltage Protection
      6. 7.3.6 Overtemperature Protection
    4. 7.4 Device Functional Modes
      1. 7.4.1 Device Enable and Shutdown Mode
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Programming the Output Voltage
        2. 8.2.2.2 Inductor Selection
        3. 8.2.2.3 Capacitor Selection
          1. 8.2.2.3.1 Input Capacitor
          2. 8.2.2.3.2 Output Capacitor
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
    3. 10.3 Thermal Considerations
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Community Resource
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

パッケージ・オプション

メカニカル・データ（パッケージ｜ピン）
サーマルパッド・メカニカル・データ

8 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.

8.1 Application Information

The TLV61224 device is intended for systems which are powered by a single-cell battery to up to two Alkaline, NiCd, or NiMH cells with a typical terminal voltage from 0.7 V to 3 V and can output 3-V voltage. Additionally, any other voltage source with a typical output voltage from 0.7 V to 3 V can be used with the TLV61224 device.

8.2 Typical Application

TLV61224 fp_lvsAM7.gifFigure 8. Typical Application Schematic

8.2.1 Design Requirements

In this example, TLV61224 device is used to design a 3-V power supply with up to 15-mA output current capability. The TLV61224 device can be powered by a single-cell battery to up to two Alkaline, NiCd, or NiMH cells with a typical terminal voltage from 0.7 V to 3 V. The input voltage range is from 0.8 V to 1.5 V for single-cell Alkaline battery input design.

8.2.2 Detailed Design Procedure

8.2.2.1 Programming the Output Voltage

At fixed voltage versions, the output voltage is programmed by an internal resistor divider. The FB pin is used to sense the output voltage. To configure the devices properly, the FB pin must be connected directly to VOUT.

8.2.2.2 Inductor Selection

To make sure that the TLV61224 devices can operate, a suitable inductor must be connected between pin VIN and pin L. Inductor values of 4.7 μH show good performance over the whole input and output voltage range.

Due to the fixed inductor current ripple control the switching frequency is defined by the inductor value. For a given switching frequency, input and output voltage the required inductance can be estimated using Equation 1.

Equation 1. TLV61224 q_6_lvs776.gif

Using inductor values greater than 4.7 μH can improve efficiency because greater values cause lower switching frequency and less switching losses. TI does not recommend using inductor values less than 2.2 μH.

To ensure reliable operation of the TLV61224 device under all load conditions, TI recommends using inductors with a current rating of 400 mA or higher. This will cover normal operation including current peaks during line and load transients.

Table 2 lists the inductor series from different suppliers that have been used with the TLV61224 converter:

Table 2. List of Inductors

VENDOR INDUCTOR SERIES
Coilcraft EPL3015
EPL2010
Murata LQH3NP
Tajo Yuden NR3015
Wurth Elektronik WE-TPC Typ S

8.2.2.3 Capacitor Selection

8.2.2.3.1 Input Capacitor

TI recommends at least a 10-μF input capacitor to improve transient behavior of the regulator and EMI behavior of the total power supply circuit. TI recommends placing a ceramic capacitor as close as possible to the VIN and GND pins of the IC.

8.2.2.3.2 Output Capacitor

For the output capacitor C2, TI recommends placing small ceramic capacitors as close as possible to the VOUT and GND pins of the IC. There are no minimum output capacitor ESR requirements for maintaining control loop stability. If, for any reason, the application requires the use of large capacitors which cannot be placed close to the IC, TI recommends using a small ceramic capacitor with a capacitance value in the range of 2.2 μF in parallel to the large capacitor. This small capacitor should be placed as close as possible to the VOUT and GND pins of the IC.

A minimum capacitance value of 4.7 μF should be used; TI recommends a value of 10 μF. Use Equation 2 to calculate the required output capacitance in case an inductor with a value greater than 4.7 μH has been selected.

Equation 2. TLV61224 q_5_lvs776.gif

8.2.3 Application Curves

TLV61224 lotr_lvsAM7.gifFigure 9. Load Transient Response
TLV61224 sten_lvsAM7.gifFigure 11. Start-Up After Enable
TLV61224 litr_lvsAM7.gifFigure 10. Line Transient Response

Table 3 lists the components used for the waveform measurements.

Table 3. List of Components:

COMPONENT REFERENCE PART NUMBER MANUFACTURER VALUE
C1 GRM188R60J106ME84D Murata 10 μF, 6.3 V
C2 GRM188R60J106ME84D Murata 10 μF, 6.3 V
L1 EPL3015-472MLB Coilcraft 4.7 μH