ZHCSIY8C October 2018 – June 2021 LM5143-Q1
PRODUCTION DATA
- 1 特性
- 2 应用
- 3 说明
- 4 Revision History
- 5 说明（续）
- 6 Pin Configuration and Functions
- 7 Specifications
-
8 Detailed Description
- 8.1 Overview
- 8.2 Functional Block Diagram
- 8.3
Feature Description
- 8.3.1 Input Voltage Range (VIN)
- 8.3.2 High-Voltage Bias Supply Regulator (VCC, VCCX, VDDA)
- 8.3.3 Enable (EN1, EN2)
- 8.3.4 Power Good Monitor (PG1, PG2)
- 8.3.5 Switching Frequency (RT)
- 8.3.6 Clock Synchronization (DEMB)
- 8.3.7 Synchronization Out (SYNCOUT)
- 8.3.8 Spread Spectrum Frequency Modulation (DITH)
- 8.3.9 Configurable Soft Start (SS1, SS2)
- 8.3.10 Output Voltage Setpoint (FB1, FB2)
- 8.3.11 Minimum Controllable On-Time
- 8.3.12 Error Amplifier and PWM Comparator (FB1, FB2, COMP1, COMP2)
- 8.3.13 Slope Compensation
- 8.3.14 Inductor Current Sense (CS1, VOUT1, CS2, VOUT2)
- 8.3.15 Hiccup Mode Current Limiting (RES)
- 8.3.16 High-Side and Low-Side Gate Drivers (HO1/2, LO1/2, HOL1/2, LOL1/2)
- 8.3.17 Output Configurations (MODE, FB2)
- 8.4 Device Functional Modes
-
9 Application and Implementation
- 9.1 Application Information
- 9.2 Typical Applications
- 10Power Supply Recommendations
- 11Layout
- 12Device and Documentation Support
- 13Mechanical, Packaging, and Orderable Information
9.2.1.2.5 Output Capacitors
- Use Equation 38 to estimate the output capacitance required to manage the output voltage overshoot during a load-off transient (from full load to no load) assuming a load transient deviation specification of 1.5% (50 mV for a 3.3-V output).
Equation 38.
- Noting the voltage coefficient of ceramic capacitors where the effective capacitance decreases significantly with applied voltage, select four 47-µF, 6.3-V, X7R, 1210 ceramic output capacitors for each channel. Generally, when sufficient capacitance is used to satisfy the load-off transient response requirement, the voltage undershoot during a no-load to full-load transient is also satisfactory.
- Use Equation 39 to estimate the peak-peak output voltage ripple of channel 1 at nominal input voltage.
Equation 39.
where
- RESR is the effective equivalent series resistance (ESR) of the output capacitors.
- 130 µF is the total effective (derated) ceramic output capacitance at 3.3 V.
- Use Equation 40 to calculate the output capacitor RMS ripple current using and verify that the ripple current is within the capacitor ripple current rating.
Equation 40.
