The ML4818 is a complete phase modulation control IC suitable for full bridge soft switching converters. Unlike conventional PWM circuits, the phase modulation technique allows for zero-voltage switching transitions and square wave drive across the transformer. The IC modulates the phases of the two sides of the bridge to control output power. The ML4818 can be operated in current mode. The delay times for the outputs are externally programmable to allow the zero-voltage switching transitions to take place. Pulse-by-pulse current limit, integrating fault detection, and soft start reset are provided. The under-voltage lockout circuit features a 6V hysteresis with a low starting current to allow off-line start up with a low power bleed resistor. A shutdown function powers down the IC, putting it into a low quiescent state.
The ML4818 is a complete phase‑modulation control IC suitable for full‑bridge soft‑switching converters. It provides zero‑voltage switching, constant‑frequency operation up to 500 kHz, and current‑mode operation with cycle‑by‑cycle current limiting.
The device is supplied in a 24‑pin narrow PDIP package and includes a buffered 5 V reference, under‑voltage lockout with 6 V hysteresis, and programmable output‑delay resistors. Detailed electrical characteristics, pin descriptions, and mechanical dimensions are provided for designers.
| Maximum operating frequency | 500 kHz |
|---|---|
| Peak output current per driver | 1.5 A |
| Supply voltage range | 12 V – 25 V |
| Operating temperature range | 0 °C – 70 °C |
The ML4818 includes four high‑current totem‑pole output drivers, each capable of 1.5 A peak output.
The under‑voltage lockout start threshold is specified as 15.5 V to 17.2 V.
The device is offered in a 24‑pin narrow Power DIP (P24) package.
The absolute maximum rating for the supply voltage (Voc) is 30 V.