Product Summary

The MAX251C/D monolithic oscillator/power-driver is specifically designed to provide isolated power for an isolated RS-485 or RS-232 data interface. The MAX251C/D drives a center-tapped transformer primary from a 5V or 3.3V DC power supply. The secondary can be wound to provide any isolated voltage needed at power levels up to 1W. The MAX251C/D consists of a CMOS oscillator driving a pair of N-channel power switches. The oscillator runs at double the output frequency, driving a toggle flip-flop to ensure 50% duty cycle to each of the switches.

Parametrics

MAX251C/D absolute maximum ratings: (1)Supply Voltage (VCC): -0.3V to +7V; (2)Control Input Voltages (SD, FS): -0.3V to (VCC + 0.3V); (3)Output Switch Voltage (D1, D2): 12V; (4)Peak Output Switch Current (D1, D2): 1A; (5)Average Output Switch Current (D1, D2): 200mA; (6)Continuous Power Dissipation (TA = +70℃): Plastic DIP (derate 9.09mW/℃ above +70℃): 727mW; SO (derate 5.88mW/℃ above +70℃): 471mW; μMAX (derate 4.10mW/℃ above +70℃): 330mW; CERDIP (derate 8.00mW/℃ above +70℃): 640mW; (7)Operating Temperature Ranges: -40℃ to +85℃; (8)Junction Temperatures: +150℃; (9)Storage Temperature Range: -65℃ to +160℃; (10)Lead Temperature (soldering, 10s): +300℃; (11)Soldering Temperature (reflow): PDIP, SO, μMAX lead(Pb)-free: +260℃; PDIP, SO, μMAX, CERDIP containing lead(Pb): +240℃.

Features

MAX251C/D features: (1)Power-Supply Transformer Driver for Isolated RS-485/RS-232 Data-Interface Applications; (2)Single 5V or 3.3V Supply; (3)Low-Current Shutdown Mode: 0.4μA; (4)Pin-Selectable Frequency: 350kHz or 200kHz; (5)8-Pin DIP, SO, and μMAX Packages.

Diagrams

MAX251C/D block diagram

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