The MAX845 provides an isolated power supply small enough to fit in thin PCMCIA cards and space-sensitive applications. It drives a low-profile center-tapped trans- former primary from a 5V or 3.3V DC power supply. The secondary can be wound to provide any isolated posi- tive or negative voltage at powers up to 750mW. The MAX845 consists of an oscillator followed by a tog- gle 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 switch- es. Internal circuitry ensures break-before-make action between the two switches. A low-power shutdown disables both the switches and the oscillator, reducing power consumption. An evalua- tion kit (MAX845EVKIT-MM) is available to evaluate low- profile 5V 40mA and 5V 100mA applications.
The MAX845 is an isolated transformer driver designed for ultra‑thin PCMCIA cards and other space‑constrained applications. It drives a low‑profile center‑tapped transformer primary from a 5 V or 3.3 V DC supply and can provide any isolated positive or negative voltage up to 750 mW. The device includes an RC oscillator and a toggle flip‑flop that generate complementary 50 % duty‑cycle square waves at half the oscillator frequency (minimum 450 kHz).
Typical applications include PCMCIA modem cards, isolated data acquisition, medical equipment, and low‑power LAN networks. The datasheet provides absolute maximum ratings, electrical characteristics, pin descriptions, and example circuits for isolated power, data conversion, RS‑485/RS‑232 interfaces, and low‑noise supplies.
| Supply Voltage (VCC) | -0.3 V to +7 V |
|---|---|
| Control Input Voltage (SD, FS) | -0.3 V to (VCC + 0.3 V) |
| Peak Output Switch Current (D1, D2) | 1 A |
| Operating Temperature Range | -40 °C to +85 °C |
| Maximum Output Switch Voltage | 12 V |
The MAX845 accepts a supply voltage (VCC) from –0.3 V to +7 V, typically 5 V or 3.3 V.
Each output switch can handle a peak current of 1 A, with a continuous power dissipation of 471 mW (SO) or 330 mW (µMAX).