Texas Instruments UCC3889EVM

Overview

UCC3889EVM from Texas Instruments is an evaluation module designed to demonstrate the UCC3889 off-line power supply controller in a non-isolated, cascaded flyback topology for low-voltage bias supply applications. It delivers dual outputs: user-selectable 3.3 V or 5 V at up to 120 mA, and a quasi-regulated 15 V at up to 35 mA, operating from 85–265 V_AC or 100–400 V_DC, targeting TMS320C24x DSP power sequencing.

For engineers reviewing the UCC3889EVM datasheet, UCC3889EVM test setup, UCC3889EVM application with TMS320C24x DSPs, or UCC3889EVM alternative evaluation platforms, this module provides validated reference design, schematic, layout, and component-level implementation guidance for transformerless off-line bias supplies requiring compact size, short-circuit protection, and low-input line protection.

Technical Context

The UCC3889EVM implements a discontinuous conduction mode (DCM), cascaded flyback topology controlled by the UCC3889 IC, using a single shared switch for both output stages. It employs variable-frequency control where t_ON is inversely proportional to input voltage and t_OFF is inversely proportional to output voltage - enabling inherent short-circuit protection without direct current sensing.

Primary regulation is performed by the UCC3889 down to ~5.4 V, followed by post-regulation via the TPS77401 LDO to achieve precise 3.3 V or 5 V outputs. The 15 V secondary output is derived from a parallel flyback stage clamped by a Zener diode (SMAZ15), intended for MOSFET driver biasing where tight regulation is not required.

Key Specifications

Availability

UCC3889EVM is available at Aetrix Electronics and suitable for TMS320C24x DSP development, low-voltage bias supply validation, and transformerless off-line power architecture evaluation requiring stable component supply and full reference design documentation.

Supply support for UCC3889EVM includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor company specializing in analog, embedded processing, and power management technologies, with decades of leadership in power conversion and DSP ecosystem solutions.

The UCC3889EVM belongs to TI's evaluation module product line, specifically engineered to accelerate adoption of the UCC3889 controller in low-power, off-line housekeeping and bias supply designs for digital signal processors and motor control systems.

FAQ

What is the primary function of the UCC3889EVM?

The UCC3889EVM is an evaluation module that demonstrates the UCC3889 off-line power supply controller in a non-isolated, cascaded flyback configuration. Its primary function is to generate regulated low-voltage bias supplies - specifically 3.3 V or 5 V at up to 120 mA, plus a 15 V auxiliary output - for TMS320C24x DSPs and similar low-power embedded systems. The UCC3889EVM enables rapid validation of transformerless, high-efficiency off-line power architectures.

Can the UCC3889EVM operate from DC input?

Yes, the UCC3889EVM supports both AC and DC input sources. It operates from 85–265 V_RMS AC or 100–400 V_DC. When using DC input, the positive and negative terminals are connected to E1 and E2 - the onboard bridge rectifier ensures proper polarity handling regardless of connection orientation. Input current must be limited to ≤100 mA for safe operation.

How do I configure the UCC3889EVM for 3.3 V output instead of 5 V?

To configure the UCC3889EVM for 3.3 V output, remove jumper R13 located near the TPS77401 LDO (U2). This changes the feedback divider network to set the regulated output to 3.3 V. The module ships with R13 installed for 5 V operation. No other hardware modifications are required - the TPS77401's adjustable version enables seamless switching between these two standard logic supply rails on the UCC3889EVM.

Does the UCC3889EVM provide isolation between input and output?

No, the UCC3889EVM implements a non-isolated, transformerless cascaded flyback topology. There is no galvanic isolation between input and output circuits - the grounds for both outputs (RTN1 and RTN2) are tied together and referenced to the input rectifier common. Users must treat all circuit nodes as potentially hazardous when powered from AC mains and follow appropriate lab safety protocols when probing the UCC3889EVM.

What protection features does the UCC3889EVM implement?

The UCC3889EVM inherits intrinsic protection features from the UCC3889 controller, including short-circuit protection achieved through t_OFF extension as output voltage collapses, and low-input line protection via t_ON modulation. It also includes discrete safeguards such as input current limiting (≤100 mA), thermal management guidance (fan recommendation above 150 V_RMS), and Zener clamping (SMAZ15) on the 15 V rail - all verified and documented in the UCC3889EVM User's Guide.