The NCP1200 is a PWM current-mode controller for low-power universal off-line supplies. It is housed in an SOIC-8 or PDIP-8 package, representing a major leap toward ultra-compact switchmode power supplies. The circuit allows the implementation of a complete offline battery charger or a standby SMPS with few external components due to a novel concept. Furthermore, an integrated output short-circuit protection allows the designer to build an extremely low-cost AC-DC wall adapter associated with a simplified feedback scheme. The controller drives low gate-charge switching devices like an IGBT or a MOSFET, requiring very small operating power. Due to current-mode control, the NCP1200 simplifies the design of reliable and cheap offline converters with extremely low acoustic generation and inherent pulse-by-pulse control. When the current setpoint falls below a given value, e.g. the output power demand diminishes, the IC automatically enters the skip cycle mode and provides excellent efficiency at light loads. This occurs at low peak current, so no acoustic noise takes place. Finally, the IC is self-supplied from the DC rail, eliminating the need for an auxiliary winding. This feature ensures operation in the presence of low output voltage or shorts.
The NCP1200 PWM Current‑Mode Controller is designed for ultra‑compact low‑power AC‑DC adapters and offline battery chargers. It operates at a fixed frequency of 40 kHz, 60 kHz or 100 kHz, provides an internal output short‑circuit protection, and includes a skip‑cycle mode for high efficiency at light loads. The device is self‑supplied from the high‑voltage rail, eliminating the need for an auxiliary winding.
Typical applications include AC‑DC adapters, offline battery chargers and auxiliary power supplies for USB, appliances and TVs. The datasheet provides detailed electrical characteristics, maximum ratings, pin functions, ordering information and package dimensions for both SOIC‑8 and PDIP‑8 versions.