1 Features

• Enables Excellent Load Transient Performance and Zero Standby Power
• Enables Smallest Output Capacitor for Tight ΔV_OUT
• No External Components Required
• <50 µA Device Current Consumption (Typical)
• 5-V to 28-V Output Monitoring Capability
• 3% Voltage Droop Detection (Patent Pending)
• 200-V Wake-Up Switch
• Enables and Disables SR Controller, Relay Control, or Other Secondary Circuits
• SOT-23 5-Pin Package

2 Applications

• <5-mW Zero-Power Standby Applications
• Adapters and Chargers for Consumer Electronics
  • Smart Phones, Tablets, Set-Top Box
• TV and Monitor Power Supplies
• Home Appliance SMPS
  • Refrigerator, Washing Machine, Air Conditioners
• Industrial Power Supplies for Lighting and Home Automation

3 Description

The UCC24650 is an easy-to-use secondary-side voltage monitor that periodically measures its own VDD voltage. A relative droop of 3% from the previous reading triggers a wake-up alert signal to a receiving primary-side regulation (PSR) controller. Its low-power consumption helps achieve <5-mW Zero-Power standby loss in many applications.

An internal 200-V MOSFET switch is applied across a ground-referenced rectifier to provide a current-limited pulse to the flyback transformer secondary winding, which couples the signal to the primary-side controller. This signal is repeated at 33 kHz until controller-driven switching activity is detected.

Relative-droop detection allows scaling to any voltage between 5 and 28 V. The wake-up alert function allows very-low standby frequency to minimize switching loss and reduction of output capacitance needed to respond to a heavy load step. This monitor is used with a controller capable of detecting the wake-up signal, such as the UCC28730 PSR flyback controller.

The UCC24650 also provides an enable and disable signal which can be used to control a secondary-side circuit during no-load conditions to reduce standby power loss. Such a circuit may be a synchronous rectifier controller or a relay driver, for example.

1. For all available packages, see the orderable addendum at the end of the data sheet.

Simplified Application Schematic

Rapid Full-Load Step Response