SNVS628H October 2009 – December 2019 LM5060
PRODUCTION DATA.
- 1 Features
- 2 Applications
- 3 Description
- 4 Revision History
- 5 Pin Configuration and Functions
- 6 Specifications
- 7 Detailed Description
-
8 Application and Implementation
- 8.1 Application Information
- 8.2
Typical Applications
- 8.2.1
Example Number 1: LM5060EVAL Design
- 8.2.1.1 Design Requirements
- 8.2.1.2
Detailed Design Procedure
- 8.2.1.2.1 VDS Fault Detection and Selecting Sense Pin Resistor RS
- 8.2.1.2.2 Turn-On Time
- 8.2.1.2.3 Fault Detection Delay Time
- 8.2.1.2.4 MOSFET Selection
- 8.2.1.2.5 Input and Output Capacitors
- 8.2.1.2.6 UVLO, OVP
- 8.2.1.2.7 POWER GOOD Indicator
- 8.2.1.2.8 Input Bypass Capacitor
- 8.2.1.2.9 Large Load Capacitance
- 8.2.1.3 Application Curves
- 8.2.2 Example Number 2: Reverse Polarity Protection With Diodes
- 8.2.3 Example Number 3: Reverse Polarity Protection With Resistor
- 8.2.1
Example Number 1: LM5060EVAL Design
- 9 Power Supply Recommendations
- 10Layout
- 11Device and Documentation Support
- 12Mechanical, Packaging, and Orderable Information
8.2.3.2.2 Fault Detection With RS and RO
Figure 41 shows an example circuit where the OUT pin is protected against a reverse battery situation with a current limiting resistor RO. When using resistor RO in the OUT pin path, the resistor RS has to be selected taking the RO resistor into account. The LM5060 monitors the VDS voltage of an external N-Channel MOSFET. The VDS fault detection voltage is the drain to source voltage threshold (VDSTH). The formula below calculates a proper RS resistor value for a desired VDSTH taking into account the voltage drop across the RO resistor.
VOFFSET is the offset voltage between the SENSE pin and the OUT pin, ISENSE is the threshold programming current, and IOUT-EN is the OUT pin bias current. When RS and RO have been selected, the following formula can be used for VDSTH min and max calculations:
The MOSFET drain-to-source current threshold is:
