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.