ZHCSFQ3B November   2016  – November 2017 TLV62568

PRODUCTION DATA.  

  1. 1 特性
  2. 2 应用
  3. 3 说明
  4. 4 修订历史记录
  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 Power Save Mode
      2. 7.3.2 100% Duty Cycle Low Dropout Operation
      3. 7.3.3 Soft Startup
      4. 7.3.4 Switch Current Limit
      5. 7.3.5 Under Voltage Lockout
      6. 7.3.6 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Enabling/Disabling the Device
      2. 7.4.2 Power Good
  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 Custom Design With WEBENCH® Tools
        2. 8.2.2.2 Setting the Output Voltage
        3. 8.2.2.3 Output Filter Design
        4. 8.2.2.4 Inductor Selection
        5. 8.2.2.5 Input and Output Capacitor Selection
      3. 8.2.3 Application Performance Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
    3. 10.3 Thermal Considerations
  11. 11器件和文档支持
    1. 11.1 器件支持
      1. 11.1.1 Third-Party Products Disclaimer
      2. 11.1.2 使用 WEBENCH® 工具定制设计方案
    2. 11.2 文档支持
      1. 11.2.1 相关文档
    3. 11.3 接收文档更新通知
    4. 11.4 社区资源
    5. 11.5 商标
    6. 11.6 静电放电警告
    7. 11.7 Glossary
  12. 12机械、封装和可订购信息

封装选项

机械数据 (封装 | 引脚)
散热焊盘机械数据 (封装 | 引脚)
订购信息

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 following section discusses the design of the external components to complete the power supply design for several input and output voltage options by using typical applications as a reference.

8.2 Typical Application

TLV62568 TLV62568P typ_app_TLV62568P.gif Figure 5. TLV62568 1.8-V Output Application

8.2.1 Design Requirements

For this design example, use the parameters listed in Table 2 as the input parameters.

Table 2. Design Parameters

DESIGN PARAMETER EXAMPLE VALUE
Input voltage 2.5 V to 5.5 V
Output voltage 1.8 V
Maximum output current 1.0 A

Table 3 lists the components used for the example.

Table 3. List of Components

REFERENCE DESCRIPTION MANUFACTURER(1)
C1 4.7 µF, Ceramic Capacitor, 10 V, X7R, size 0805, GRM21BR71A475KA73L Murata
C2 10 µF, Ceramic Capacitor, 10 V, X7R, size 0805, GRM21BR71A106KE51L Murata
L1 2.2 µH, Power Inductor, SDER041H-2R2MS Cyntec
R1,R2,R3 Chip resistor,1%,size 0603 Std.
C3 Optional, 6.8 pF if it is needed Std.

8.2.2 Detailed Design Procedure

8.2.2.1 Custom Design With WEBENCH® Tools

Click here to create a custom design using the TLV62568 device with the WEBENCH® Power Designer.

  1. Start by entering the input voltage (VIN), output voltage (VOUT), and output current (IOUT) requirements.
  2. Optimize the design for key parameters such as efficiency, footprint, and cost using the optimizer dial.
  3. Compare the generated design with other possible solutions from Texas Instruments.

The WEBENCH Power Designer provides a customized schematic along with a list of materials with real-time pricing and component availability.

In most cases, these actions are available:

  • Run electrical simulations to see important waveforms and circuit performance
  • Run thermal simulations to understand board thermal performance
  • Export customized schematic and layout into popular CAD formats
  • Print PDF reports for the design, and share the design with colleagues

Get more information about WEBENCH tools at www.ti.com/WEBENCH.

8.2.2.2 Setting the Output Voltage

An external resistor divider is used to set output voltage according to Equation 2.

When sizing R2, in order to achieve low current consumption and acceptable noise sensitivity, use a maximum of 200 kΩ for R2. Larger currents through R2 improve noise sensitivity and output voltage accuracy but increase current consumption.

Equation 2. TLV62568 TLV62568P Eq_Vo.gif

A feed forward capacitor, C3 improves the loop bandwidth to make a fast transient response (shown in Figure 19). 6.8-pF capacitance is recommended for R2 of 100-kΩ resistance. A more detailed discussion on the optimization for stability vs. transient response can be found in SLVA289.

8.2.2.3 Output Filter Design

The inductor and output capacitor together provide a low-pass filter. To simplify this process, Table 4 outlines possible inductor and capacitor value combinations. Checked cells represent combinations that are proven for stability by simulation and lab test. Further combinations should be checked for each individual application.

Table 4. Matrix of Output Capacitor and Inductor Combinations

VOUT [V] L [µH](1) COUT [µF](2)
4.7 10 22 2x 22 100
0.6 ≤ VOUT < 1.2 1 +
2.2 ++(3)
1.2 ≤ VOUT < 1.8 1 + +
2.2 ++(3) +
1.8 ≤ VOUT 1 + + +
2.2 ++(3) + +
(1) Inductor tolerance and current de-rating is anticipated. The effective inductance can vary by +20% and -30%.
(2) Capacitor tolerance and bias voltage de-rating is anticipated. The effective capacitance can vary by +20% and -50%.
(3) This LC combination is the standard value and recommended for most applications.

8.2.2.4 Inductor Selection

The main parameters for inductor selection is inductor value and then saturation current of the inductor. To calculate the maximum inductor current under static load conditions, Equation 3 is given:

Equation 3. TLV62568 TLV62568P Eq_IL_peak_PWM_lvsae8.gif

where

  • IOUT,MAX is the maximum output current
  • ΔIL is the inductor current ripple
  • fSW is the switching frequency
  • L is the inductor value

It is recommended to choose a saturation current for the inductor that is approximately 20% to 30% higher than IL,MAX. In addition, DC resistance and size should also be taken into account when selecting an appropriate inductor.

8.2.2.5 Input and Output Capacitor Selection

The architecture of the TLV62568 allows use of tiny ceramic-type output capacitors with low equivalent series resistance (ESR). These capacitors provide low output voltage ripple and are thus recommended. To keep its resistance up to high frequencies and to achieve narrow capacitance variation with temperature, it is recommended to use X7R or X5R dielectric.

The input capacitor is the low impedance energy source for the converter that helps provide stable operation. A low ESR multilayer ceramic capacitor is recommended for best filtering. For most applications, 4.7-µF input capacitance is sufficient; a larger value reduces input voltage ripple.

The TLV62568 is designed to operate with an output capacitor of 10 µF to 47 µF, as outlined in Table 4.

8.2.3 Application Performance Curves

VIN = 5 V, VOUT = 1.8 V, L = 2.2 μH, TA = 25°C, unless otherwise noted.

TLV62568 TLV62568P D004_SLVSD89_TLV62568.gif
Figure 6. 1.2-V Output Efficiency
TLV62568 TLV62568P D006_SLVSD89_TLV62568.gif
Figure 8. 2.5-V Output Efficiency
TLV62568 TLV62568P D009_SLVSD89_TLV62568.gif
VIN = 5 V
Figure 10. Load Regulation
TLV62568 TLV62568P D011_SLVSD89_TLV62568.gif
VIN = 5 V
Figure 12. Switching Frequency vs Load
TLV62568 TLV62568P D013_SLVSD89_TLV62568.gif
IOUT = 0.5 A
Figure 14. PWM Operation
TLV62568 TLV62568P D015_SLVSD89_TLV62568.gif
IOUT = 1 A
Figure 16. Startup with Load
TLV62568 TLV62568P D017_SLVSD89_TLV62568.gif
Load Step 0.3 A to 1 A, 1A/µs slew rate
Figure 18. Load Transient
TLV62568 TLV62568P D005_SLVSD89_TLV62568.gif
Figure 7. 1.8-V Output Efficiency
TLV62568 TLV62568P D007_SLVSD89_TLV62568.gif
Figure 9. 3.3-V Output Efficiency
TLV62568 TLV62568P D010_SLVSD89_TLV62568.gif
VOUT = 1.8 V
Figure 11. Line Regulation
TLV62568 TLV62568P D012_SLVSD89_TLV62568.gif
IOUT = 0.5 A
Figure 13. Switching Frequency vs Input Voltage
TLV62568 TLV62568P D014_SLVSD89_TLV62568.gif
IOUT = 0.1 A
Figure 15. Power Save Mode Operation
TLV62568 TLV62568P D016_SLVSD89_TLV62568.gif
IOUT = 0.1 A
Figure 17. Startup with Load
TLV62568 TLV62568P D018_SLVSD89_TLV62568.gif
Load Step 0.3 A to 1 A, 1A/µs slew rate C3 = 6.8 pF
Figure 19. Load Transient with a feed forward capacitor