MAX253Transformer Driver forIsolated RS-485 InterfaceGeneral DescriptionBenefits and Features The MAX253 monolithic oscillator/power-driver is • Simple Power-Supply Transformer Driver Design for specifically designed to provide isolated power for an Isolated RS-485/RS-232 Data-Interface Applications isolated RS-485 or RS-232 data interface. The device • Single 5V or 3.3V Supply drives a center-tapped transformer primary from a 5V • Low-Current Shutdown Mode: 0.4µA or 3.3V DC power supply. The secondary can be • Pin-Selectable Frequency: 350kHz or 200kHz wound to provide any isolated voltage needed at power levels up to 1W. • 8-Pin DIP, SO, and µMAX® Packages Take Minimal Board Space 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- Ordering Information flop to ensure 50% duty cycle to each of the switches. Internal delays are arranged to ensure break-before- PART TEMPRANGEPIN-PACKAGE make action between the two switches. MAX253CPA 0°C to +70°C 8 Plastic DIP The SD pin puts the entire device into a low-power MAX253CSA 0°C to +70°C 8 SO shutdown state, disabling both the power switches and MAX253CUA 0°C to +70°C 8 µMAX oscillator. MAX253C/D 0°C to +70°C Dice* Applications MAX253EPA -40°C to +85°C 8 Plastic DIP MAX253ESA -40°C to +85°C 8 SO Isolated RS-485/RS-232 Power-Supply Transformer Driver MAX253ESA/V -40°C to +85°C 8 SO MAX253MJA -55°C to +125°C 8 CERDIP** High Noise-Immunity Communications Interface *Contact factory for dice specifications. Isolated and/or High-Voltage Power Supplies **Contact factory for availability and processing to MIL-STD-883. Bridge Ground Differentials Devices are also available in a lead(Pb)-free/RoHS-compliant package. Specify lead-free by adding a (+) to the part number Medical Equipment when ordering. Process Control /V Denotes an automotive qualified part. Typical Operating Circuit VIN 5V ON / OFF C1 4 6 OUTPUT SD VCC 1 5V @ 200mA D1 C3 C2 MAX253 3 8 FS D2 FREQUENCY SWITCH GND1 GND2 2 7 µMAX is a registered trademark of Maxim Integrated Products, Inc. 19-0226; Rev 3; 2/15