Electronic Design

I2C-Programmable DC-DC Converter Chip Gives Handhelds A Hand

When I ask companies about design-ins, most bring up the worldwide lack of qualified power-supply designers. The need grows more acute as the number of rails in new products, particularly in battery-powered consumer products, increases. One solution is to customize power-conversion ICs for specific end uses and make their implementation as simple as possible.

So far, the most ambitious venture combines nine dc-dc converters on a single die in a 1-cm2 package and makes them programmable via an I2C bus. Though MOSFETs and passives go off-chip, Summit Microelectronics' SMB120 packs four buck converters, three boost converters, one inverting buck/boost converter, and one linear 3.3-V low-dropout regulator.

Programmable functions include independent sequencing and slew rates, plus the ability to margin output voltages to ±0.5% accuracy. For diagnostics and monitoring, the interface offers input and output monitoring for undervoltage and overvoltage conditions, low/missing battery detection, ac-adapter detection, and a RESET output. On-chip EEPROM memory stores all configuration data, with 96 bytes available for user-data storage. The device can be programmed during development and then used in a "fixed" configuration. Or, it may be reprogrammed in-system via the I2C interface.

Initially, designs are created using an evaluation board and GUI software. The board automatically generates a HEX data file that can be transmitted to Summit for review and approval. The company then programs the production devices prior to final electrical test. The design kit software can be downloaded from Summit's Web site for review.

The SMB120 operates directly from +2.7- to +5.5-V inputs, suiting it for one-cell lithium-ion (Li-ion) battery applications. Higher input voltages (two-cell Li-ion) also can be accommodated in many cases. The 64-pad QFN-64 package is lead-free, and it complies with the European Union's Restrictions on Hazardous Substances directive. Available now in production quantities, the SMB120 costs $5.95 each in lots of 1000.

Summit Microelectronics

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