ZHCSJU9E January 2007 – June 2019 TPS40077
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 Minimum Pulse Duration
- 7.3.2 Slew Rate Limit On VDD
- 7.3.3 Setting The Switching Frequency (Programming The Clock Oscillator)
- 7.3.4 Loop Compensation
- 7.3.5 Shutdown and Sequencing
- 7.3.6 Boost and LVBP Bypass Capacitance
- 7.3.7 Internal Regulators
- 7.3.8 Power Dissipation
- 7.3.9 Boost Diode
- 7.3.10 Synchronous Rectifier Control
- 7.4 Programming
-
8 Application and Implementation
- 8.1 Application Information
- 8.2
Typical Applications
- 8.2.1
Buck Regulator 8-V to 16-V Input, 1.8-V Output at 10 A
- 8.2.1.1 Design Requirements
- 8.2.1.2
Detailed Design Procedure
- 8.2.1.2.1
Power Train Components
- 8.2.1.2.1.1 Output Inductor, LOUT
- 8.2.1.2.1.2 Output Capacitor, COUT, ELCO and MLCC
- 8.2.1.2.1.3 Input Capacitor, CIN ELCO and MLCC
- 8.2.1.2.1.4 Switching MOSFET, QSW
- 8.2.1.2.1.5 Rectifier MOSFET, QSR
- 8.2.1.2.1.6 Timing Resistor, RT
- 8.2.1.2.1.7 Feed-Forward and UVLO Resistor, RKFF
- 8.2.1.2.1.8 Soft-Start Capacitor, CSS
- 8.2.1.2.1.9 Short-Circuit Protection, RILIM and CILIM
- 8.2.1.2.1.10 Boost Voltage, CBOOST and DBOOST (Optional)
- 8.2.1.2.1.11 Closing the Feedback Loop, RZ1, RP1, RPZ2, RSET1, RSET2, CZ2, CP2, and CPZ1
- 8.2.1.2.1
Power Train Components
- 8.2.1.3 Application Curves
- 8.2.1
Buck Regulator 8-V to 16-V Input, 1.8-V Output at 10 A
- 8.3 Additional System Examples
- 9 Layout
- 10器件和文档支持
- 11机械、封装和可订购信息
8.2.1.2.1.7 Feed-Forward and UVLO Resistor, RKFF
A resistor connected to the KFF pin of the IC feeds into the ramp generator. This resistor provides current into the ramp generator proportional to the input voltage. The ramp is then adjusted to compensate for different input voltages. This provides the voltage feed-forward feature of the TPS40077.
The same resistor also sets the undervoltage lockout point. The input start voltage should be used to calculate a value for RKFF. For this module, the minimum input voltage is 8 V; however, due to tolerances in the IC, a start voltage of 10% less than the minimum input voltage is selected. The start voltage for RKFF calculation is 7.2 V. Using Equation 35, RKFF can be selected.
where
- RKFF and RT are in kΩ
Equation 35 gives an RKFF value of 156 kΩ. The closest lower standard value of 154 kΩ should be selected. This gives a minimum start voltage of 7.1 V.