MAX845

PCMCIA Modem Cards
Isolated Data Acquisition
Isolated Interface Power Supply
Noise-Immunity Communications Interface
Bridging Ground Differences
Medical Equipment
Process Control
Low-Power LAN Networks

Supply Voltage (V_CC) .............................................-0.3V to +7V
Control Input Voltage (SD, FS) ..................-0.3V to (V_CC + 0.3V)
Peak Output Switch Current (D1, D2) ....................................1A
Output Switch Voltage (D1, D2) ...........................................12V
Average Output Switch Current (D1, D2) ........................200mA
Continuous Power Dissipation (T_A = +70°C)
SO (derate 5.88mW/°C above +70°C).........................471mW
MAX (derate 4.10mW/°C above +70°C) ....................330mW
Operating Temperature Range .......................-40°C to +85°C
Storage Temperature Range ........................-65°C to +160°C
Junction Temperature....................................................+150°C
Lead Temperature (soldering, 10sec) ...........................+300°C
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.

The MAX845 provides an isolated power supply small enough to fit in thin PCMCIA cards and space-sensitive applications. MAX845 drives a low-profile center-tapped transformer primary from a 5V or 3.3V DC power supply. The secondary can be wound to provide any isolated positive or negative voltage at powers up to 750mW.

The MAX845 consists of an oscillator followed by a toggle flip-flop. The flip-flop generates two 50% duty-cycle square waves, which are complementary at half the oscillator frequency (450kHz, min). These two signals drive the ground-referenced N-channel power switches. Internal circuitry of MAX845 ensures break-before-make action between the two switches.

A low-power shutdown disables both the switches and the oscillator, reducing power consumption. An evaluation kit (MAX845EVKIT-MM) is available to evaluate lowprofile 5V 40mA and 5V 100mA applications.