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Microchip Technology Expands Power Management Portfolio with 120 mA Regulated, Inductor-Free Charge Pump DC-to-DC Converter

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Expanding its power management portfolio, Microchip Technology announced today two new regulated charge pump DC-to-DC converters. The MCP1252 and MCP1253, 120mA regulated charge pump devices, give users a space-saving, power management product that accomplish DC-to-DC conversions in a battery-operated environment without the need of an inductor. These devices require less external components than many other charge pump devices and unlike switching regulators, do not require an inductor. From a 2.7 through 5.5 V input source, theses devices provide either a fixed 3.3 V or 5.0 V output or an adjustable output voltage of 1.5 V to 5.5 V. In addition, these devices have a low drain current of 60 uA and a shutdown current of 0.1 uA. Both offer a power-good output that can detect an out-of-regulation situation with an output voltage accuracy of +/- 2.5 percent maximum, 0.5 percent typical. Unlike low-dropout (LDO) regulators, these devices offer a DC-to-DC conversion method that automatically operates in buck and boost modes, meaning that the input voltage can either be higher or lower than the output voltage. These features, combined with their ability to efficiently convert various energy sources to required voltage/current levels, makes them ideal candidates for DC-to-DC conversions in compact battery-operated systems such as cell phones, PDAs, MP3 players, pagers, hand-held meters and wireless controllers such as game joy-sticks. "Voltage converters generate desired voltage levels from sources such as a common DC-bus or a battery. Often, charge pumps are the best choice for applications requiring a combination of simple, low power and low cost solution options," said Jim Mack, product marketing manager for Microchip's Analog and Interface Products Division. "Microchip has many solutions for applications requiring low-power consumption, and we have been broadening our system solutions to meet our customers' design needs." Choosing between the operating frequencies of 650kHz for the MCP1252 or 1.0MHz for the MCP1253 enables the user to either minimize the external component size with the higher frequency device or to avoid critical system frequencies with the lower frequency device. In addition, the devices offer internal thermal and short-circuit protection. Microchip Technology Inc. manufactures the popular PICmicroý field-programmable RISC microcontrollers, which serve 8- and 16-bit embedded control applications, and a broad spectrum of high performance linear and mixed-signal, power management and thermal management devices. The Company also offers complementary microperipheral products including interface devices; microIDý RFID devices; serial EEPROMs; and the patented KEELOQ security devices. This synergistic product portfolio targets thousands of applications and a growing demand for high-performance designs in the automotive, communications, computing, consumer and industrial control markets. The Company's quality systems are ISO 9001 (1994 version) and QS9000 (1998 version) certified. Microchip is headquartered in Chandler, Arizona with design facilities in Mountain View, California, Bangalore, India; and a European Design Center in Lausanne, Switzerland; semiconductor fabrication facilities in Tempe and Chandler, Arizona; Gresham, Oregon; and Puyallup, Washington; and assembly and test operations near Bangkok, Thailand. Microchip Technology Inc. Web Site Tel: 480-792-4111

These two new parts are positive regulating charge pump DC-DC converters. The only difference between the MCP1252 and MCP1253 is the frequency of operation. They are capable of 120 mA of load current and are regulated charge pumps, a classical charge pump doubler that goes out through a regulator on the same chip. The company offers a fixed-selectable converter that allows selection of a fixed 3.3V output or a 5V output. An adjustable version is also available that uses an adjust pin for selecting voltage output. Microchip expects that more customers will want the fixed output because it does not require any external circuitry, as is needed by the adjustable version. Probably the most important feature for this chip is its ability to switch between buck and boost modes. That's important for designs with batteries. For example, a lithium battery will charge to 4.1 V or 4.2 V and then gradually discharge down to 3.0 V or 2.7 V. However, if you want a 3.3 V output the entire time then initially you will need a buck-mode converter and then when the voltage goes below the output mode voltage you will need a boost-mode converter. This device does both operations by tracking the battery and always putting out a constant output voltage. The fact that this is a regulating charge pump is also a pretty neat feature. Looking at the history of charge pumps you find that the complaint heard from many customers was about the charge pump having significant voltage droop when loads were placed on them. This device regulates the voltage. Typically designers have to be aware of noise. Microchip has a noise spec in the form of ripple voltage. The ripple voltage is 50 mVp-p. For example, if you look at an output voltage of say 3.3 V there will be a component of the switching frequency riding on that signal. Customers will want to know how much of the ripple is getting through the regulator, and the 50 mV ripple is a very respectable spec. You also can reduce the ripple by adding filtering to the output. Designers may also consider these converters for driving white LEDs. White LEDs typically require 20 mA to 30 mA each, so you can drive three or four of them in parallel with this device. The company has looked at the market and determined if LEDs are driven in series higher voltage is required, or if in parallel, higher current. Many white LEDs have banks of three and four so this converter works very well with a parallel design. In the press release it discusses choosing the operating frequency. This product enables the user to minimize the external component size with a higher frequency or avoid critical system frequencies with the lower frequency device. If a manufacturer of a phone or MP3 player, for example, has a critical frequency in the 600 kHz range, you wouldn't want something near that frequency within the product because it could produce a beat frequency. So the designer would choose the higher frequency, a 1 MHz part, to eliminate the problem. Additionally, if you have a 1 MHz clock in a product then you don't want a converter that is close to that 1 MHz frequency, rather you would choose the lower frequency converter. Designers will probably migrate toward the higher frequency part simply because they will use smaller external components. To reiterate, the most important feature about this device is that it is a buck-boost regulated charge pump. That means that no matter if your input voltage is above or below the output you will get a positive regulated output voltage. So you can have a variable battery voltage and this part will put out a constant regulated output voltage. The MCP1252 and MCP1253 are available in 8-pin MSOP packages and are specified over a temperature range of -40oC to +85oC. Pricing in 1,000-unit quantities for the MCP1252 and MCP1253 is $1.61 each. Samples and volume production are scheduled for December 2002. Data Sheet

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