AC-DC|Design
IC Used in Design
2019.09.25
Points of this article
・The BM1R001xxF series consists of five models, with different compulsion OFF times.
・Packages are simple and compact SOP8 packages.
・A shunt regulator features low current consumption and high precision, and can reduce power consumption in standby mode by reducing the control circuit current.
・Synchronous rectifying controllers support all modes, from discontinuous to critical to continuous, and can also be used in PWM converters.
In this article, an example of design of synchronous rectification in an AC-DC converter with diode rectification, using the BM1R001xxF series of secondary-side synchronous rectifying controller ICs, is explained. A brief summary of the BM1R001xxF series of ICs used in this design is also given.
IC Used in Design: BM1R001xxF Series
The BM1R001xxF series are essentially synchronous rectifying controller ICs to implement synchronous rectification in the secondary-side output stage of an AC-DC converter. The lineup consists of five products, BM1R00146F to BM1R00150F, and the “compulsion OFF times”, which are the mask times to prevent MOSFET gate turn-on on the secondary side by a resonance waveform occurring at the DRAIN terminal, are different for each model. Details are explained in the section on IC selection, but these different models are provided because an appropriate compulsion OFF time must be selected based on the conditions of the circuit in which synchronous rectification is implemented. The products are provided in simple, compact SOP8 packages.
The main internal function blocks are the shunt regulator block and the synchronous rectifying controller block. The shunt regulator features low current consumption and high precision, and can reduce standby power consumption by decreasing the current in the control circuit. The synchronous rectifying controller supports all modes from discontinuous to critical to continuous mode operation, and can be used in PWM converters as well. During continuous mode operation, operation is possible without primary-side switching synchronization signal input, and the number of components and space used can be reduced.
Moreover, the shunt regulator and the synchronous rectifying controller are constructed in separate chips. By making the shunt regulator independent, both high-side switching and low-side switching can be accommodated. In addition, the synchronous rectifying controller alone can be used. Thus use in many different applications is possible.
The operating power supply voltage range is wide, extending from 2.7 V to 32 V, for use in applications with various outputs. Through adoption of high-voltage 120 V processes, drain voltages can be monitored directly.
The key features, specifications, and applications are summarized below.
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As indicated in the “Design Procedure”, it is recommended that an appropriate model be selected from the BM1R001xxF series on the basis of the specifications of the circuit in which synchronous rectification is implemented.
List of articles related to the「IC Used in Design」
- Introduction
- Design Procedure
- Power Supply Specifications and Replacement Circuit
- Synchronous Rectifying Circuit Section: Selection of Synchronous Rectifying MOSFET
- Synchronous Rectification Circuit Section: Power Supply IC Selection
- Synchronous Rectification Circuit Section: Selection of Peripheral Circuit Components-C1, R3 at MAX_TON Pin, and VCC Pin
- Synchronous Rectification Circuit Section: Selection of Peripheral Circuit Components-D1, R1, R2 at DRAIN Pin
- Shunt Regulator Circuit Section: Selection of Peripheral Circuit Components
- Troubleshooting ①: Case When Secondary-Side MOSFET Suddenly Turns OFF
- Troubleshooting ②: Case When Secondary-Side MOSFET Turns On Due to Resonance Under Light Loading
- Troubleshooting ③: Case When, Due to Surge, VDS2 Rises to Above Secondary-Side MOSFET VDS Voltage
- Comparison of Efficiency of Diode Rectification and Synchronous Rectification
- Points to Note Relating to PCB Layout
- Summary
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Basic of AC-DC Conversion
Basic studies to understand AC-DC converters and to go designing.
AC-DC
- Basic
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Design
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Overview of Design Method of PWM AC-DC Flyback Converters
- Want are Isolated Flyhback Convertors?
- Isolated Flyback Converter Basics: What is Switching AC-DC Conversion?
- Isolated Flyback Converter Basics: What are Characteristics of Flyback Converter?
- Isolated Flyback Converter Basics: Flyback Converter Operation and Snubber
- Isolated Flyback Converter Basics: What are Discontinuous Mode and Continuous Mode?
- Design Procedure
- Determining Power Supply Specifications
- Choosing an IC for Design
- Designing Isolated Flyback Converter Circuits
- Designing Isolated Flyback Converter Circuits: Transformer Design (Calculating numerical values)
- Designing Isolated Flyback Converter Circuits: Transformer Design (Structural Design) – 1
- Designing Isolated Flyback Converter Circuits: Transformer Design (Structural Design) – 2
- Designing Isolated Flyback Converter Circuits: Selecting Critical Components ? MOSFET related – 1
- Designing Isolated Flyback Converter Circuits: Selecting Critical Components ? MOSFET related – 2
- Designing Isolated Flyback Converter Circuits: Selecting Critical Components ? CIN and Snubber
- Designing Isolated Flyback Converter Circuits: Selecting Critical Components ? Output Rectifier and Cout
- Designing Isolated Flyback Converter Circuits: Selecting Critical Components ? VCC of IC
- Designing Isolated Flyback Converter Circuits: Selecting Critical Components – IC Settings Etc.
- Designing Isolated Flyback Converter Circuits: Addressing EMI and Output Noise
- Example Board Layout
- Summary
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Overview of Design Examples of AC-DC Non-isolated Buck Converters
- What are Buck Converters? – Basic Operation and Discontinuous Mode vs. Continuous Mode
- Selection of Power Supply ICs and Design Examples
- Selecting Critical Components: Input Capacitor C1 and VCC Capacitor C2
- Selecting Critical Components: Inductor L1
- Selecting Critical Components: Current Sense Resistor R1
- Selecting Critical Components: Output Capacitor C5
- Selecting Critical Components: Output Rectifying Diode D4
- EMI Countermeasures
- Board Layout and Summary
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Introduction
- Design Procedure
- IC Used in Design
- Power Supply Specifications and Replacement Circuit
- Synchronous Rectifying Circuit Section: Selection of Synchronous Rectifying MOSFET
- Synchronous Rectification Circuit Section: Power Supply IC Selection
- Synchronous Rectification Circuit Section: Selection of Peripheral Circuit Components-C1, R3 at MAX_TON Pin, and VCC Pin
- Synchronous Rectification Circuit Section: Selection of Peripheral Circuit Components-D1, R1, R2 at DRAIN Pin
- Shunt Regulator Circuit Section: Selection of Peripheral Circuit Components
- Troubleshooting ①: Case When Secondary-Side MOSFET Suddenly Turns OFF
- Troubleshooting ②: Case When Secondary-Side MOSFET Turns On Due to Resonance Under Light Loading
- Troubleshooting ③: Case When, Due to Surge, VDS2 Rises to Above Secondary-Side MOSFET VDS Voltage
- Comparison of Efficiency of Diode Rectification and Synchronous Rectification
- Points to Note Relating to PCB Layout
- Summary
-
Introduction
- Power Supply ICs Used in Design: Optimized for SiC MOSFETs
- Design Example Circuit
- Transformer T1 Design – 1
- Transformer T1 Design – 2
- Selecting Critical Components: MOSFET Q1
- Selecting Critical Components: Input Capacitor and Balancing Resistor
- Selecting Critical Components: Switch Setting Resistors for Overload Protection Points
- Selecting Critical Components: VCC-Related Components of Power Supply ICs
- Selecting Critical Components: Components Related to Power Supply IC BO (Brownout) Pins
- Selecting Critical Components: Components Related to Snubber Circuits
- Selecting Critical Components: MOSFET Gate Drive Adjustment Circuit
- Selecting Critical Components: Output Rectifying Diode
- Selecting Critical Components: Output Capacitors, Output Setting and Control Components
- Selecting Critical Components: Current Sense Resistors and Components Related to Detection Pins
- Selecting Critical Components: Components for Dealing with EMI and Output Noise
- PCB Layout Example
- Example Circuit and Component List
- Evaluation Results: Efficiency and Switching Waveform
- Summary
-
Overview of Design Method of PWM AC-DC Flyback Converters
- Evaluation
- Product Information
- FAQ