When you study any of the upcoming new technologies, the main part of the system is Power Supply Unit. Power Supply Unit is the heart of the system, which supplies power to all the ICs, Controllers, Driving Circuits, etc. This places higher demands on the Power Supply Units. Recently, a company named Keysight Technologies have published an e-book titled “4 Ways to Build Your Power Supply Skill Set”. This e-book gives tips to be considered to design engineers while designing power supply.
Download link: E-book
Source: Keysight Technologies
STMicroelectronics’ STCH03 offline Pulse-Width Modulation (PWM) controller combines high integration with accurate constant-current output using primary-side regulation enabling economical mobile chargers, power adapters, or auxiliary supplies to meet stringent eco-design limits for average efficiency and standby power.
At heavier loads, the STCH03 maximizes efficiency by operating in quasi-resonant mode with zero-voltage switching (ZVS) controlled by detecting transformer demagnetization. The detection circuitry also provides for line-voltage feed-forward control, which ensures accurate constant-current regulation. Maintaining operation at the boundary of continuous (CCM) and discontinuous (DCM) transformer current, the STCH03 limits the converter’s maximum operating frequency to 167kHz depending on line/load conditions, and implements valley-skipping for best efficiency as the load reduces.
Energy-saving features including zero-power high-voltage startup circuitry, as well as low quiescent current and burst-mode switching when the load is very low or disconnected, keep standby power below 10mW to help chargers and adapters meet tough legislation such as the incoming CoC Tier 2 power supply efficiency specifications. Low peak current eliminates audible noise at light load or no load, and the STCH03 features an innovative adaptive under-voltage lockout (UVLO) to ensure consistent operation at low values of transformer auxiliary bias voltage.
With the advantage of accurate primary-side constant-current regulation, the STCH03 eliminates output-current sensing components, thereby reducing the charger bill of materials (BOM). The integrated startup circuitry, which consumes zero power when inactive, also saves external components.
The STCH03 contains many more features to help save external components and BOM cost, including over-temperature and over-voltage protection (OTP, OVP) with auto-restart or optional latching operation in the STCH03L variant. In addition, soft-start prevents high peak currents at startup, and output under-voltage protection lets the device operate safely in case of an output short-circuit or low output voltage under constant-current control.
- Advanced power management for ultra-low standby power consumption (under 10 mW at 230 VAC)
- Fully integrated primary side constant current output regulation (CC)
- 650 V embedded HV start-up circuit with zero power consumption.
- Quasi-resonant (QR) zero-voltage-switching (ZVS) operation
- Accurate and adjustable output OVP with options auto-restart (STCH03) or latched (STCH03L) after fault
- Output undervoltage protection (UVP) with auto-restart
- Input voltage feedforward compensation for mains-independent CC regulation
- Embedded thermal shutdown
- Intelligent frequency jitter for EMI suppression
Unwanted transients emanating from the power line back to the line-driver’s output and back-EMF generated by the coupling circuit when the load is disconnected and connected, and vice versa, create undesirable over-voltage conditions. Back-EMF is also generated when the line driver outputs are toggled from high to low impedance state, if significant current was flowing at the disconnect time. The MAX44211 power line communications driver most often is placed facing the power line with an isolating stage between them. In case of such over-stress conditions, external protection is required to protect the MAX44211 and downstream circuits.
The internal ESD clamping structure is present inside MAX44211 (see Figure) to protect the part from ESD or sub-microsecond events. When the application has hazards where these events can occur frequently and for comparatively longer time, it is recommended to have external protection circuitry. Failure to accommodate an output protection can result in over-stressing the outputs (OUT+/ OUT-) and eventually damage the part.
This application note provides insights and information on how to add external protection circuitry at the outputs of the MAX44211. A circuit using VAVDD = 15V is used in this application note.
The figure shows the internal ESD clamping protection structure.
Download PDF: MAX44211-Output-Protection
Source: Maxim Integrated