International Rectifier Introduces µPFC^TM IC that Simplifies High Density Designs from 75W to 4kW

IR's new One Cycle Control (OCC) approach in the IR1150 delivers the performance of continuous conduction mode (CCM) PFC with the simplicity, reliability and low component count of a discontinuous current mode (DCM) circuit for PFC applications.

Power factor (PF) is the relationship between AC voltage and current waveforms and is a measure of "power quality" that affects the efficiency of electrical transmission networks. With unity PF as the ultimate goal, the IR1150 enables 0.999 PF with only 4% total harmonic distortion, enabling AC-DC applications to conform to international legislative requirements.

Technical Highlights
The One Cycle Control method used in the IR1150 controller does not have an analog multiplier, input voltage sensing, or fixed oscillator ramp, simplifying circuitry and reducing component count. Instead, IR's OCC uses a proprietary integrator with a reset circuit: The output of the error amplifier is integrated over each clock cycle to generate a variable-slope ramp. This variable ramp is compared with the error voltage and subtracted from the current sense signal to generate the PWM gate drive.

Traditionally, Continuous Conduction Mode PFC offers high performance for high power applications above 250W. However, solutions using multiplier techniques are complex and require many design stages and a high component count, making CCM solutions very expensive and not appropriate for low power, price sensitive applications like laptop power adapters.

In low power applications from 75W to 250W, Discontinuous Current Mode systems are used for their simplicity and low system cost. However, as system power increases to 100W and above, DCM systems can be very large (low power density) due to high peak currents and EMI filter requirements.

For example, in a typical high power system such as a 1kW server SMPS, IR's µPFC solution has 40% fewer resistors and capacitors, halves the number of current transformers used and saves 50% of the PFC control PCB area compared to traditional multiplier-based CCM systems. In lower power applications where power density is critical, such as high power laptop and LCD TV adapters, an IR1150 controller in CCM mode means reduced peak currents and a 43% reduction in EMI filter needs. This translates into a 16% reduction in PCB space and an increase in power density of 10% for a 120W system.

In addition, a dedicated Over Voltage Protection pin offers greater protection for high power systems and the IC includes features such as enable- and micro-power start-up and "sleep mode" for compliance with energy efficiency standards such as 1W standby, Blue Angel and Energy Star.

The IR1150 is an elegant solution to PFC legislation such as IEC 1000-3-2 in Europe, JIC C 61000-3-2 in Japan and the China Compulsory Certificate (CCC) for products using more than 75W. As manufacturers implement PFC in response to these energy standards, the IR1150 control IC simplifies effective PFC solutions, and enables a single design that can be used worldwide.

For design help see Demonstration Board IRAC1150-300W.

Availability and Pricing

The devices in the IR1150 family are available immediately. Pricing is US $1.05 each for the IR1150S/IR1150SPbF and US $1.38 each for the IR1150IS/IR1150ISPbF, all in 10,000-unit quantities. Pricing is subject to change.