Philips Semiconductors, a division of Royal Philips Electronics, today announced a new current-mode Pulse Width Modulation (PWM) controller integrated circuit (IC). The PUCC3801 is an upgrade for the industry standard UCC380x Controller family, and is ideal for a range of low cost applications such as mains adapters for laptop computers, printer power supplies, low-power off-line power supplies, set-top box power supply units, and personal digital assistant (PDA) chargers. The PUCC3801 incorporates all control and protection functions required for implementing an off-line continuous-mode flyback or forward converter. The PUCC3801 provides additional advantages including the provision of an internal 100kHz fixed-frequency oscillator that removes the need for an external resistor and capacitor (RC) network. This is a critical factor in reducing component count and leads to a faster and cheaper assembly.

"Until now, the industry standard UCC3800-UCC3809 devices were sole source products," said Edwin Kluter, product marketing manager, Power Conversion ICs, Philips Semiconductors. "The introduction of the PUCC3801 low cost upgrade, opens up a wealth of opportunities for the customers who are looking to enhance existing designs while reducing costs."

Other key features of the PUCC3801 include under-voltage detection, over-voltage detection, and over-current detection with cycle-by-cycle limit. A 15 V input clamp is included to protect products from excessive chip voltage and high drive capability, along with an error amplifier with external compensation pin, and an internal bandgap reference and leading-edge blanking. The PUCC3801 is currently sampling. Full production will begin in Q4 and be available in DIP and SO8 packaging.

Philips Semiconductor, Tel: 503 439 6110.

The timing of this modulator coincides neatly with the appearance of low-cost power supplies used in a plethora of electronic equipment. Designers need this type controller to meet the pressures for fewer parts in the BOM and the subsequent lower overall cost. This is especially true since the pulse width modulator controllers can represent a significant chunk of the power supply cost.

The PUCC3801 is a current-mode Pulse Width Modulated (PWM) controller containing all the control and protection functions necessary to implement an off-line, flyback regulator. The low start-up current of the PUCC3801 means that the dissipation does not become excessive at high input voltages. An optocoupler or forward converter also may be interconnected to the PUCC3801 with a minimum number of external components. Very low start-up supply current; 50 uA typical Low operating supply current; 1.2 mA typical. Accurate, internally-trimmed, fixed frequency oscillator (100 kHz). No external timing components needed.

The PUCC3801 is an upgrade of the industrial standard UC380x family of controllers. In addition to the standard features found in similar controllers, the new PWM controller incorporates an internal 100kHz fixed frequency oscillator. It eliminates the need for an external RC oscillator network, and shrinks board space needed as well as the cost. Philips also thought about electromagnetic interference and ways for designers to meet the more stringent standards around the world. They added a randomized frequency jitter feature to help designers reduce EMI and slope compensation. It also helps simplify the EMI filter design and reduce cost.

The PUCC3801 is available in standard DIP and SO-8 packages which offers drop-in replacement for standard counterparts.

Data sheet