UC3901 Isolated Feedback Generator | TI.com

UC3901 (ACTIVE) Isolated Feedback Generator

Isolated Feedback Generator - UC3901
Datasheet
 

Description

The UC1901 family 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, these devices feature an amplitude modulation system which allows a loop error signal to be coupled with a small RF transformer or capacitor.

The programmable, high-frequency oscillator within the UC1901 series 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 a SMPS.

An additional feature is a status monitoring circuit which 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.

Since these devices can also be used as a DC driver for optical couplers, the benefits of 4.5 to 40V supply operation, a 1% accurate reference, and a high gain general purpose amplifier offer advantages even though an AC system may not be desired.

Features

  • An 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 5MHz
  • Modulator Synchronizable to an External Clock
  • Loop Status Monitor

Parametrics

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Part number Order Topology Control method Frequency (Max) (kHz) UVLO thresholds on/off (V) Duty cycle (Max) (%) Gate drive (Typ) (A) Features Rating Operating temperature range (C) Package Group Package size: mm2:W x L (PKG)
UC3901 Order now                 Catalog     0 to 70     PDIP | 14
SOIC | 14
SOIC | 16    
See datasheet (PDIP)
14SOIC: 52 mm2: 6 x 8.65 (SOIC | 14)
16SOIC: 77 mm2: 7.5 x 10.3 (SOIC | 16)    
UC2901 Order now     Voltage     5000     3.9/3.9     50     0         Catalog     -40 to 85     PDIP | 14
SOIC | 14    
See datasheet (PDIP)
14SOIC: 52 mm2: 6 x 8.65 (SOIC | 14)