Electronic Design

Power-Management ICs Meet Application Needs With Higher Levels Of Integration

Power-management ICs continue to evolve to meet specific application requirements. For example, some multifunction power-manager ICs focus on portable power systems. These ICs answer the portable system manufacturers' need to develop small-size, high-performance, feature-packed products that permit shorter system development cycles.

Occupying anywhere from 50% to 70% less board space than discrete solutions, these ICs combine voltage regulation, battery-charging, and power control into one integrated solution. Similar applications with older ICs require more chips because they don't incorporate the same level of integration as this new generation of power-manager ICs.

These ICs are well suited for powering components commonly found in digital consumer electronics, such as digital still cameras/camcorders, portable MP3/MEPG4 players, GPS terminals, personal digital assistants (PDAs), portable LCD TVs, and the next generation of "smart" mobile phones.

A typical power-manager IC can include step-down, step-up, inverting, low-dropout (LDO) outputs, LED drivers, and a lithium-ion (Li-ion) battery charger. Multiple step-down converters can provide the core voltage and peripheral I/O rails in a processor-based system. Typical power control functions include individual channel enable/shutdown, power-up/down sequencing, power-up slew rate control, and static and dynamic output voltage control.

The battery charger usually is fully programmable for all the Li-ion constant-current/constant-voltage (CC/CV) parameters. Some of these ICs add power-system diagnostics and monitoring via an I2C serial interface and digital status outputs.

Typically, the IC can power the system while independently charging the battery. This reduces the charge and discharge cycles on the battery. Also, it enables proper charge termination and system operation with an absent or defective battery pack. It can select the USB port or ac adapter as the system power source. In the USB configuration, the host can select charge rates. In the ac adapter configuration, an external resistor sets the magnitude of the charge current.

All of the configuration data for the SMB122 power-manager IC from Summit Microelectronics is programmed via the easy-to-use PC-based graphical user interface (GUI) and stored in on-chip EEPROM, of which 96 bytes are available for data storage (see the figure). The IC can be programmed during development and then used in a "fixed" configuration or reprogrammed in-system via the I2C interface.

To speed product development, the SMB122 includes a companion evaluation board and GUI software so designers can quickly design a prototype power supply using the IC. This development tool lets designers easily manipulate the characteristics of their systems. A typical design kit includes menu-driven Microsoft Windows GUI software to automate programming tasks. It also includes all of the necessary hardware to interface to the parallel or USB port of a laptop or PC.

When the designer completes design and prototyping, the evaluation kit automatically generates a Hex data file that can be transmitted to the IC manufacturer for review and approval. The IC manufacturer then assigns a unique customer identification code to the Hex file and programs the customer's production devices prior to final electrical test operations. This ensures the device will operate properly in the end application.

The SMB122 operates directly from 2.7- to 6.0-V input, suiting it for one-cell Li-ion applications as well as line-powered applications. Simple applications configuration can accommodate higher input voltages. Available now in production quantities, the SMB122 costs $6.12 each in lots of 10,000.

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