News Releases

January 18, 2000

Sanken Introduces the HWB-Series Resonant Switching Power Supplies Featuring Ultra-Low Noise

Sanken Electric has launched the HWB-Series resonant switching power supplies that feature compact, low-cost design and low noise (ripple voltage no more than 5 mV) comparable to series regulators. Available in six models (15-, 30-, and 60-watt output power, each with rated output voltages of either 5-V or 15-V) the products are due to ship from late February (60-watt model) to mid-March (15- and 30-watt models).

The HWB Series dramatically reduces noise interference from the inverter block by combining Sanken's original SMZ (Softswitched Multiresonant Zerocross) technology using a proprietary hybrid resonance IC and resonant transformer in a compact, low-cost design.

Conventionally, bulky yet low-noise series regulators were employed for instrumentation equipment, semiconductor process and testing facilities, control devices, and medical equipment that are particularly sensitive to noise interference from their power supplies.
Where switching power supplies are used, L/C or other types of noise filters are required in the input and output circuits to lower the relatively high noise levels. This tends to increase the effort involved in circuit design and component selection. The HWB-Series switching power supplies offer an ideal solution to these problems by providing ultra-low noise level comparable to the series regulators, in the sizes and weights far lower than the latter. A low-cost switching power supply can now be incorporated within a wide range of industrial equipment where low noise interference is a fundamental requirement.

The suggested retail price is ¥9,800 for the 15-watt model, ¥11,800 for the 30-watt model, and ¥14,800 for the 60-watt model. A ¥300 million sales target is projected for the first fiscal year.

♦Features
Sanken Electric has launched the HWB-Series resonant switching power supplies that feature compact, low-cost design and low noise (ripple voltage no more than 5 mV) comparable to series regulators. Available in six models (15-, 30-, and 60-watt output power, each with rated output voltages of either 5-V or 15-V) the products are due to ship from late February (60-watt model) to mid-March (15- and 30-watt models).

The HWB Series dramatically reduces noise interference from the inverter block by combining Sanken's original SMZ (Softswitched Multiresonant Zerocross) technology using a proprietary hybrid resonance IC and resonant transformer in a compact, low-cost design.

Conventionally, bulky yet low-noise series regulators were employed for instrumentation equipment, semiconductor process and testing facilities, cont>

(1) Low ripple voltage
	No more than 5 mVp-p (observed with a 100 MHz oscilloscope, excluding spikes)
(2) Low-noise terminal voltage
	Approx. 20 dB of margin for VCCI Class-B, FCC Class-B and CISPR Class-B
(3) Low noise field
	Complies with the requirements of VCCI Class-B, FCC Class-B, and CISPR Class-B.
(4) Universal line input
	The input line voltage is continuously variable from 85 to 284 VAC or automatically switchable between 85 to 132 VAC and 170 to 284 VAC.
(5) Compact, lightweight, low-cost design
	Approx. one-quarter the volume and weight and half the cost of series regulators.
(6) CE marking
	CE marking obtained for the LVD.
(7) Compliance with safety standards
	Due in compliance with the UL1950, CSA950, and EN60950 Standards. Compliant with the IEC601-1 Standard (for medical equipment).
(8) Parallel operation
	Supports parallel operation (60 watts)if properly adjusted with the ovrcurrent protection control.
(9) Non-standard output voltages
	Available in 5 to 28 V.
(10) Options
	C: Cover (output derating) RC: Output remote On/Off control (external voltage control) Medical equipment compatibility: Low leakage current of 50µA or less (typically 0.25 mA or less)
(11) Charge-free warranty period
	3 years

♦Applications

• Alternative for series regulators
• Instrumentation, semiconductor process and testing equipment, control devices, medical equipment, and other similar applications where low noise is a fundamental requirement.

♦Comparisons with Series Regulators

	HWB Series	Dropper Power Supply	Conventional Switching SWA
Volume and weight	• Low volume & weight R Compact system design * The 60-W class device (92H x 39W x 190 + 9.8L) is 75% smaller than dropper power supply.	• Large = Large overall system design	• Small R Compact system design
Noise	• Low noise = No noise filter required.	• Low noise	• High noise level R Bulky noise filters comparable to the power supply itself in size are required in the input and output circuits. The analog nature of noise makes power supply design difficult.
Ripple voltage	5mV	2mV~3mV	50mV
Spike noise	5-10 mV	None	100-150 mV
Terminal noise voltage	20-dB margin to VCCI Class-B	None	VCCI Class-B or Level A (5 to 10-dB margin)
Input voltage range	• Continuously variable over a wide range due to circuit configuration and devices used.	• Narrow variable range due to tap switching	• Continuously variable over a wide range due to circuit configuration and devices used.
Conversion efficiency	75% or more	Around 40%	75% or more

♦Glossary

	×Ripple voltage	:	Noise component that develops across output terminals and is synchronized with the line and/or switching frequencies.
	×Terminal noise voltage	:	RF noise that develops across the line input terminals and returns to the line side.
	×Noise field strength	:	Strength of electromagnetic noise emissions from the power supply
	×Spike noise	:	Impulse noise with small pulse width caused by switching operation
	×Series regulator	:	A serial regulating transistor is inserted in the rectifier's DC output so the load voltage is regulated through the voltage drop across the serial transistor. This type of regulator has a relatively low efficiency due to power loss across the serial transistor.
	×SMZ system	:	Voltage control and soft switching are achieved using three resonant operations. This type of regulator features low noise, high efficiency, and low cost with a low circuit component requirement.