1FEATURES

• Controlled Baseline

– One Assembly/Test Site, One Fabrication

Site

• Extended Temperature Performance of –55°C

to 125°C

• Enhanced Diminishing Manufacturing Sources

(DMS) Support

• Enhanced Product-Change Notification

• Qualification Pedigree (1)

• Amplitude-Modulation System for Transformer

Coupling an Isolated Feedback Error Signal

• Low-Cost Alternative to Optical Couplers

• Internal 1% Reference and Error Amplifier

• Internal Carrier Oscillator Usable to 5 MHz

• Modulator Synchronizable to an External

Clock

• Loop Status Monitor

DESCRIPTION

The UC2901 is designed to solve many of the problems associated with closing a feedback control loop across a

voltage isolation boundary. As a stable and reliable alternative to an optical coupler, UC2901 features an

amplitude modulation system that allows a loop error signal to be coupled with a small RF transformer or

capacitor.

The programmable, high-frequency oscillator within the UC2901 permits the use of smaller, less-expensive

transformers, which can readily be built to meet the isolation requirements of today's line-operated power

systems. As an alternative to RF operation, the external clock input to these devices allows synchronization to a

system clock or to the switching frequency of an SMPS.

An additional feature is a status monitoring circuit that provides an active low output when the sensed error

voltage is within ±10% of the reference. The DRIVERA output, DRIVERB output, and STATUS output are

disabled until the input supply has reached a sufficient level to allow proper operation of the device.

Because these devices also can be used as a DC driver for optical couplers, the benefits of 4.5 V to 40 V supply

operation, a 1% accurate reference, and a high-gain general-purpose amplifier offer advantages, even though an

AC system may not be desired.