ZHCSE52B September 2015 – May 2019 TPS57140-EP
PRODUCTION DATA.
- 1 特性
- 2 应用范围
- 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 Bootstrap Voltage (Boot)
- 7.3.4 Low-Dropout Operation
- 7.3.5 Error Amplifier
- 7.3.6 Voltage Reference
- 7.3.7 Adjusting the Output Voltage
- 7.3.8 Enable and Adjusting UVLO
- 7.3.9 Slow-Start or Tracking Pin (SS/TR)
- 7.3.10 Overload Recovery Circuit
- 7.3.11 Constant Switching Frequency and Timing Resistor (RT/CLK Pin)
- 7.3.12 Overcurrent Protection and Frequency Shift
- 7.3.13 Selecting the Switching Frequency
- 7.3.14 How to Interface to RT/CLK Pin
- 7.3.15 Power Good (PWRGD Pin)
- 7.3.16 Overvoltage Transient Protection (OVTP)
- 7.3.17 Thermal Shutdown
- 7.3.18 Small-Signal Model for Loop Response
- 7.3.19 Simple Small-Signal Model for Peak-Current-Mode Control
- 7.3.20 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 Selecting the Switching Frequency
- 8.2.2.2 Output Inductor Selection (LO)
- 8.2.2.3 Output Capacitor
- 8.2.2.4 Catch Diode
- 8.2.2.5 Input Capacitor
- 8.2.2.6 Slow-Start Capacitor
- 8.2.2.7 Bootstrap Capacitor Selection
- 8.2.2.8 UVLO Set Point
- 8.2.2.9 Output Voltage and Feedback Resistors Selection
- 8.2.2.10 Compensation
- 8.2.3 Application Curves
- 9 Power Supply Recommendations
- 10Layout
- 11器件和文档支持
- 12机械、封装和可订购信息
10.3 Power-Dissipation Estimate
The following formulas show how to estimate the IC power dissipation under CCM operation. Do not use these equations used if the device is working in DCM.
The power dissipation of the IC includes conduction loss (Pcon), switching loss (Psw), gate-drive loss (Pgd), and supply current (Pq).
Equation 54. 
Equation 55. 
Equation 56. 
Equation 57. 
where
- IOUT is the output current (A).
- Rdson is the on-resistance of the high-side MOSFET (Ω).
- VOUT is the output voltage (V).
- VIN is the input voltage (V).
- ƒSW is the switching frequency (Hz).
So,
Equation 58. 
For a given TA,
Equation 59. 
For a given TJMAX = 150°C
Equation 60. 
where
- PTOT is the total device power dissipation (W).
- TA is the ambient temperature (°C).
- TJ is the junction temperature (°C).
- Rth is the thermal resistance of the package (°C/W).
- TJ(max) is maximum junction temperature (°C).
- TA(max) is 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 trace resistance, that impact the overall efficiency of the regulator.