ZHCSI27C April 2018 – October 2021 LM5036
PRODUCTION DATA
- 1 特性
- 2 應(yīng)用
- 3 說明
- 4 Revision History
- 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 High-Voltage Start-Up Regulator
- 7.3.2 Undervoltage Lockout (UVLO)
- 7.3.3 Reference Regulator
- 7.3.4 Oscillator, Synchronized Input
- 7.3.5 Voltage-Mode Control
- 7.3.6 Primary-Side Gate Driver Outputs (LSG and HSG)
- 7.3.7 Half-Bridge PWM Scheme
- 7.3.8 Maximum Duty Cycle Operation
- 7.3.9 Pre-Biased Start-Up Process
- 7.3.10 Zero Duty Cycle Operation
- 7.3.11 Enhanced Cycle-by-Cycle Current Limiting with Pulse Matching
- 7.3.12 Reverse Current Protection
- 7.3.13 CBC Threshold Accuracy
- 7.3.14 Hiccup Mode Protection
- 7.3.15 Hiccup Mode Blanking
- 7.3.16 Over-Temperature Protection (OTP)
- 7.3.17 Over-Voltage / Latch (ON_OFF Pin)
- 7.3.18 Auxiliary Constant On-Time Control
- 7.3.19 Auxiliary On-Time Generator
- 7.3.20 Auxiliary Supply Current Limiting
- 7.3.21 Auxiliary Primary Output Capacitor Ripple
- 7.3.22 Auxiliary Ripple Configuration and Control
- 7.3.23 Asynchronous Mode Operation of Auxiliary Supply
- 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 Custom Design With WEBENCH? Tools
- 8.2.2.2 Input Transient Protection
- 8.2.2.3 Level-Shift Detection Circuit
- 8.2.2.4 Applications with VIN > 100-V
- 8.2.2.5 Applications without Pre-Biased Start-Up Requirement
- 8.2.2.6 UVLO Voltage Divider Selection
- 8.2.2.7 Over Voltage, Latch (ON_OFF Pin) Voltage Divider Selection
- 8.2.2.8 SS Capacitor
- 8.2.2.9 SSSR Capacitor
- 8.2.2.10 Half-Bridge Power Stage Design
- 8.2.2.11 Current Limit
- 8.2.2.12 Auxiliary Transformer
- 8.2.2.13 Auxiliary Feedback Resistors
- 8.2.2.14 RON Resistor
- 8.2.2.15 VIN Pin Capacitor
- 8.2.2.16 Auxiliary Primary Output Capacitor
- 8.2.2.17 Auxiliary Secondary Output Capacitor
- 8.2.2.18 Auxiliary Feedback Ripple Circuit
- 8.2.2.19 Auxiliary Secondary Diode
- 8.2.2.20 VCC Diode
- 8.2.2.21 Opto-Coupler Interface
- 8.2.2.22 Full-Bridge Converter Applications
- 8.2.3 Application Curves
- 9 Power Supply Recommendations
- 10Layout
- 11Device and Documentation Support
- 12Mechanical, Packaging, and Orderable Information
封裝選項
機械數(shù)據(jù) (封裝 | 引腳)
- RJB|28
散熱焊盤機械數(shù)據(jù) (封裝 | 引腳)
訂購信息
7.3.1 High-Voltage Start-Up Regulator
The LM5036 device contains a high-voltage VCC start-up regulator that allows the input pin (VIN) to be connected directly to an input voltage up to 100-V. Higher input voltages can be accommodated by adding some additional external parts, as described in Section 8.2.2.4. When the UVLO pin voltage is greater than VSD (0.38-V typical), the start-up regulator is enabled to charge an external capacitor connected to the VCC pin. The output voltage of the VCC regulator is regulated at VCC (7.8-V typical). The VCC regulator provides power to the reference (REF) regulator. The regulator output at VCC is internally current limited to ICC(Lim) (81-mA typical) . The value of the VCC capacitor depends on the total system design, and its start-up characteristics. The recommended range of values for the VCC capacitor is 0.47-μF to 10-μF.
LM5036 can power itself using its internal high-voltage start-up linear regulator, but internal power dissipation can be reduced by powering VCC from an auxiliary switched mode supply. LM5036 device integrates all of the functions needed to implement a low-cost and easy-to-design isolated fly-buck auxiliary supply based on the constant-on-time (COT) control scheme. The primary output VAUX1 of the auxiliary supply must be connected through a diode to the VCC pin, as shown in Figure 7-1. The auxiliary supply must raise the VCC voltage above the internally generated VCC voltage in order to shut off the internal start-up regulator. Powering VCC from an auxiliary switched mode supply improves efficiency while reducing the power dissipation of the controller IC. The VCC under-voltage (UV) circuit will still function in this mode, requiring that VCC never falls below its UV threshold during the start-up sequence. The VCC regulator series pass transistor includes a diode between VCC and VIN that should not be forward biased in normal operation. Therefore, the auxiliary VCC voltage should never exceed the VIN voltage.
Figure 7-1 External VCC Bias Supply Connection