Text

Murata Manufacturing Co., Ltd. has developed a ripple detection control method DC-DC converter (*1) "Ripple Converter Extreme" MPDRX series, realizing the highest level of transient load response performance (*2) in the industry.

The Ripple detection control method determines the ON/OFF of the switching element (*3) by directly comparing the output voltage with the reference voltage (*4). Since this method eliminates the integration circuit (*5) essential for the previous PWM control method (*6), it became possible to shorten the response time. Since the control responds at high speed to the fluctuation of a transient load current, compared with the PWM control used previously, the highest level of response performance in the industry is realized, the range of voltage fluctuation (*7) is decreased by approximately 25%, and the recovery time (*8) is reduced by approximately 20%.

Also, since it is possible to maintain the output voltage with a higher precision, the external capacity (*9) can be smaller. Consequently, when it is used for low-voltage / heavy-current / high load current fluctuation applications such as DSP, microprocessors, and ASIC, the total mounting area can be greatly reduced from the previous models. Both MPDRX001S at 5V input, 0.8 to 1.8V/16A output and MPDRX003S at 12V input, 0.8 to 1.8V/12A output comply with the industrial de facto standard footprint dimensions of 33.0x13.5mm.

They are scheduled for mass-production in July 2005. The monthly production capacity is projected to reach 50,000 by August 2005.

Background

Many information processing ICs such as DSP and microprocessors are used for telecommunication equipment and intelligent home appliances. These ICs require a low voltage and a heavy current power source and are normally driven with DC-DC converters. Since the load current rapidly fluctuates depending on whether there is a process or task to action or not, the output voltage for the DC-DC converter also fluctuates thereby creating a problem of not being able to maintain a precise voltage necessary for these ICs. Previously, in order to control this output voltage fluctuation, a large number of external capacitors were usually connected to the DC-DC converter output. However, due to mounting area restrictions, high response DC-DC converters providing necessary voltage precision under less external capacity were in demand.

Terminology

*1 DC-DC Converter:
DC voltage converter, where a DC voltage is input and a different DC voltage is output. It is used to gain a set stable voltage from a power source with voltage fluctuation.

*2 Transient Load Response Performance:
Performance pertaining to the DC-DC converter's output voltage fluctuation during rapid fluctuation of the load current, in terms of DC-DC converter connection load. It is desirable for the output voltage of the DC-DC converter to be maintained at a set value even when the load current rapidly fluctuates. However, in reality, when load current rapidly decreases, output voltage temporarily increases, and when load current rapidly increases, output voltage temporarily decreases.

*3 Switching Element:
DC-DC converters realize high-efficiency voltage conversion by switching internal switch ON/OFF. The switch used in such a way (normally a transistor or an FET), is called switching element.

*4 Reference Voltage:
A target value voltage, when the DC-DC converter's output voltage is controlled to be a specific value. It is normally generated within the DC-DC converter.

*5 Integration Circuit:
Circuit to output the voltage by time-integrating the difference between two input terminals. It becomes a delay time circuit theoretically.

*6 PWM Control Method:
A control method to generate a switching signal, by comparing the integrated result of the difference between the output voltage of the DC-DC converter and the reference voltage, with the triangular oscillating waveform. When the output voltage is low the switch is turned ON to raise the output voltage. When the output voltage is high the switch is turned OFF to reduce the output voltage so it is held close to the reference voltage. It is simple to design, and is the most commonly used method.

*7 Range of Voltage Fluctuation:
When the load current fluctuates as in Figure 1, dV1 and dV2 are the ranges of voltage fluctuation. The shorter the range of voltage fluctuation, the closer a DC-DC converter becomes to being ideal.

Figure 1

*8 Recovery Time:
When the load current fluctuates as in Figure 1, dT1 and dT2 are the recovery times. The shorter the recovery time, the closer a DC-DC converter becomes to being ideal.

*9 External Capacity:
Indicates the capacitor connected in parallel to the DC-DC converter output. Transient load fluctuation may be lessened by adding external capacity.

Features

(MPDRX001S)

• 5V input
• 16A output current
• Super high-speed transient load response
• Wide set output range (0.8V to 1.8V, may be set with single resistance)
• Equipped with ON/OFF remote control, short-circuit protection, and over temperature protection
• Complies with industry de facto standard configuration and footprint

(MPDRX003S)

• 12V input
• 12A output current
• Super high-speed transient load response
• Wide set output range (0.8V to 1.8V, may be set with single resistance)
• Equipped with ON/OFF remote control, short-circuit protection, and over temperature protection
• Complies with industry de facto standard configuration and footprint

Applications

Ideal for applications requiring low voltage and heavy current, such as telecommunication equipment and intelligent home appliances

Dimensions

Electric Performance

Indicates a typical transient load response waveform.
Transient response is greatly improved compared with the previous PWM products.

Starting Month for Sales

July 2005       * Evaluation samples are available as of June 2005.

Production Capacity

Scheduled to produce 50,000 units per month starting in August 2005

Patents

Three patents pending