Transformer Driver for Isolated RS-485 Interface

General Description
The MAX253 monolithic oscillator/power-driver is specifically designed to provide isolated power for an solated RS-485 or RS-232 data interface. The device 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 evels up to 1W.
The MAX253 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. nternal delays are arranged to ensure break-before- make action between the two switches.
The SD pin puts the entire device into a low-power
shutdown state, disabling both the power switches and oscillator.

Applications
Isolated RS-485/RS-232 Power-Supply Transformer Driver
High Noise-Immunity Communications Interface Isolated and/or High-Voltage Power Supplies Bridge Ground Differentials Medical Equipment Process Control

Features
♦ Power-Supply Transformer Driver for Isolated RS-485/RS-232 Data-Interface Applications
♦ Single 5V or 3.3V Supply
♦ Low-Current Shutdown Mode: 0.4µA
♦ Pin-Selectable Frequency: 350kHz or 200kHz
♦ 8-Pin DIP, SO, and µMAX® Packages