ZHCSK76 September 2019 LM74202-Q1
PRODUCTION DATA.
- 1 特性
- 2 應(yīng)用
- 3 說明
- 4 修訂歷史記錄
- 5 Pin Configuration and Functions
- 6 Specifications
- 7 Parameter Measurement Information
-
8 Detailed Description
- 8.1 Overview
- 8.2 Functional Block Diagram
- 8.3
Feature Description
- 8.3.1 Undervoltage Lockout (UVLO)
- 8.3.2 Overvoltage Protection (OVP)
- 8.3.3 Reverse Battery Protection
- 8.3.4 Hot Plug-In and In-Rush Current Control
- 8.3.5 Overload and Short Circuit Protection
- 8.4 Device Functional Modes
-
9 Application and Implementation
- 9.1 Application Information
- 9.2
Typical Application
- 9.2.1 Design Requirements
- 9.2.2 Detailed Design Procedure
- 9.2.3 Application Curves
- 10Power Supply Recommendations
- 11Layout
- 12器件和文檔支持
- 13機械、封裝和可訂購信息
封裝選項
機械數(shù)據(jù) (封裝 | 引腳)
- PWP|16
散熱焊盤機械數(shù)據(jù) (封裝 | 引腳)
- PWP|16
訂購信息
8.3.4 Hot Plug-In and In-Rush Current Control
The device is designed to control the in-rush current upon insertion of a card into a live backplane or other "hot" power source. This limits the voltage sag on the supply voltage and prevents unintended resets of the system power. The controlled start-up also helps to eliminate conductive and radiative interferences. An external capacitor connected from the dVdT pin to RTN defines the slew rate of the output voltage at power-on as shown in Figure 27 and Figure 28.
Figure 27. Output Ramp Up Time tdVdT is Set by C(dVdT) The dVdT pin can be left floating to obtain a predetermined slew rate (tdVdT) on the output. When the terminal is left floating, the devices set an internal output voltage ramp rate of 23.9 V / 1.6 ms. A capacitor can be connected from dVdT pin to RTN to program the output voltage slew rate slower than 23.9 V / 1.6 ms. Use Equation 1 and Equation 2 to calculate the external C(dVdT) capacitance.
Equation 1 governs slew rate at start-up.
where
- I(dVdT) = 4.7 µA (typical)
- Gain(dVdT) = dVdT to VOUT gain = 24.6
The total ramp time (tdVdT) of V(OUT) for 0 to V(IN) can be calculated using Equation 2.
The inrush current can be calculated by Equation 3
| CdVdT = 22 nF | COUT = 47 µF | RILIM = 5.36 kΩ |