ZHCSJ43 December 2018 TPS54360B
PRODUCTION DATA.
- 1 特性
- 2 应用
- 3 说明
- 4 修订历史记录
- 5 Pin Configuration and Functions
- 6 Specifications
-
7 Detailed Description
- 7.1 Overview
- 7.2 Functional Block Diagram
- 7.3
Feature Description
- 7.3.1 Fixed Frequency PWM Control
- 7.3.2 Slope Compensation Output Current
- 7.3.3 Pulse Skip Eco-mode
- 7.3.4 Low Dropout Operation and Bootstrap Voltage (BOOT)
- 7.3.5 Error Amplifier
- 7.3.6 Adjusting the Output Voltage
- 7.3.7 Enable and Adjusting Undervoltage Lockout
- 7.3.8 Internal Soft Start
- 7.3.9 Constant Switching Frequency and Timing Resistor (RT/CLK) pin)
- 7.3.10 Accurate Current Limit Operation and Maximum Switching Frequency
- 7.3.11 Synchronization to RT/CLK pin
- 7.3.12 Overvoltage Protection
- 7.3.13 Thermal Shutdown
- 7.3.14 Small Signal Model for Loop Response
- 7.3.15 Simple Small Signal Model for Peak-Current-Mode Control
- 7.3.16 Small Signal Model for Frequency Compensation
- 7.4 Device Functional Modes
-
8 Application and Implementation
- 8.1 Application Information
- 8.2
Typical Application
- 8.2.1 Design Requirements
- 8.2.2
Detailed Design Procedure
- 8.2.2.1 Custom Design with WEBENCH® Tools
- 8.2.2.2 Selecting the Switching Frequency
- 8.2.2.3 Output Inductor Selection (LO)
- 8.2.2.4 Output Capacitor
- 8.2.2.5 Catch Diode
- 8.2.2.6 Input Capacitor
- 8.2.2.7 Bootstrap Capacitor Selection
- 8.2.2.8 Undervoltage Lockout Set Point
- 8.2.2.9 Output Voltage and Feedback Resistors Selection
- 8.2.2.10 Minimum VIN
- 8.2.2.11 Compensation
- 8.2.2.12 Discontinuous Conduction Mode and Eco-mode Boundary
- 8.2.2.13 Power Dissipation Estimate
- 8.2.3 Application Curves
- 8.3 Other Applications
- 9 Power Supply Recommendations
- 10Layout
- 11器件和文档支持
- 12机械、封装和可订购信息
8.2.2.13 Power Dissipation Estimate
The following formulas show how to estimate the TPS54360B power dissipation under continuous conduction mode (CCM) operation. Do not use these equations if the device is operating in discontinuous conduction mode (DCM).
The power dissipation of the IC includes conduction loss (PCOND), switching loss (PSW), gate drive loss (PGD) and supply current (PQ). Example calculations are shown with the 12-V typical input voltage of the design example.
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Where:
- IOUTis the output current (A).
- RDS(on) is the on-resistance of the high-side MOSFET (Ω).
- VOUT is the output voltage (V).
- VINis the input voltage (V).
- ƒswis the switching frequency (Hz).
- triseis the SW pin voltage rise time and can be estimated by trise = VIN x 0.16ns/V + 3.0ns.
- QGis the total gate charge of the internal MOSFET.
- IQis the operating nonswitching supply current.
Therefore,
For given TA,
For given TJMAX = 150°C
Where:
- Ptot is the total device power dissipation (W).
- TAis the ambient temperature (°C).
- TJis the junction temperature (°C).
- RTHis the thermal resistance of the package (°C/W).
- TJMAXis maximum junction temperature (°C).
- TAMAXis maximum ambient temperature (°C).
There are additional power losses in the regulator circuit due to the inductor AC and DC losses, the catch diode and PCB trace resistance impacting the overall efficiency of the regulator.