Transformer Driver for MAX253 Isolated RS-485 Interface General Description Benefits 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: 0.4A 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 8-Pin DIP, SO, and MAX Packages Take Minimal levels up to 1W. 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. PART TEMP RANGE PIN-PACKAGE Internal delays are arranged to ensure break-before- make action between the two switches. MAX253CPA 0C to +70C 8 Plastic DIP MAX253CSA 0C to +70C 8 SO The SD pin puts the entire device into a low-power shutdown state, disabling both the power switches and MAX253CUA 0C to +70C 8 MAX oscillator. MAX253C/D 0C to +70C Dice* MAX253EPA -40C to +85C 8 Plastic DIP Applications MAX253ESA -40C to +85C 8 SO Isolated RS-485/RS-232 Power-Supply MAX253ESA/V -40C to +85C 8 SO Transformer Driver MAX253MJA -55C to +125C 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. Devices are also available in a lead(Pb)-free/RoHS-compliant Bridge Ground Differentials package. Specify lead-free by adding a (+) to the part number Medical Equipment when ordering. /V Denotes an automotive qualified part. Process Control Typical Operating Circuit V IN 5V ON / OFF C1 46 OUTPUT SD V 5V 200mA CC 1 D1 C3 C2 MAX253 3 8 FS D2 FREQUENCY SWITCH GND1 GND2 27 MAX is a registered trademark of Maxim Integrated Products, Inc. 19-0226 Rev 3 2/15Transformer Driver for MAX253 Isolated RS-485 Interface Absolute Maximum Ratings Supply Voltage (V ) ...............................................-0.3V to +7V Operating Temperature Ranges CC Control Input Voltages (SD, FS) .................-0.3V to (V + 0.3V) MAX253C ........................................................0C to +70C CC Output Switch Voltage (D1, D2).............................................12V MAX253E .....................................................-40C to +85C Peak Output Switch Current (D1, D2)......................................1A MAX253MJA ...................................................-55C to +125C Average Output Switch Current (D1, D2) .........................200mA Junction Temperatures Continuous Power Dissipation (T = +70C) MAX253C /E ..........................................................+150C A Plastic DIP (derate 9.09mW/C above +70C) .............727mW MAX253MJA .................................................................+175C SO (derate 5.88mW/C above +70C)..........................471mW Storage Temperature Range .............................-65C to +160C MAX (derate 4.10mW/C above +70C) .....................330mW Lead Temperature (soldering, 10s) .................................+300C CERDIP (derate 8.00mW/C above +70C)..................640mW Soldering Temperature (reflow) PDIP, SO, MAX lead(Pb)-free .....................................+260C PDIP, SO, MAX, CERDIP containing lead(Pb)............+240C Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Electrical Characteristics (V = 5V 10%, T = T to T , unless otherwise noted. Typical values are at T = +25C.) CC A MIN MAX A PARAMETER CONDITIONS MIN TYP MAX UNITS Switch On-Resistance D1, D2 100mA 1.5 4.0 FS = V or open 250 350 500 CC Switch Frequency kHz V = 0V 150 200 300 FS Operating Supply Current (Note 1) No load, V = 0V, FS low 0.45 5.0 mA SD Shutdown Supply Current (Note 2) SD = V 0.4 A CC High 2.4 V Shutdown Input Threshold Low 0.8 A Shutdown Input Leakage Current 10 pA High 2.4 FS Input Threshold V Low 0.8 V = 0V 50 A FS FS Input Leakage Current FS = V 10 pA CC Start-Up Voltage 2.5 2.2 V Note 1: Operating supply current is the current used by the MAX253 only, not including load current. Note 2: Shutdown supply current includes output switch-leakage currents. www.maximintegrated.com Maxim Integrated 2