Microchip Combines Discrete Functions in Five ICs

Microchip Technology Inc. (Chandler, AZ) has introduced the TC1303/TC1304 and TC1313 series of power management integrated circuits that combine a synchronous buck switching regulator, low dropout regulator (LDO) and power-good function into single-chip solutions. These five new devices are targeted for a variety of battery-operated and dual-output-voltage systems.

The five power management devices include: The TC1303A, a 500-milliAmp synchronous buck regulator and 300-milliAmp LDO with a power-good function on the dc-to-dc converter output. The TC1303B is a 500-milliAmp synchronous-buck regulator and 300-milliAmp LDO with a power-good function on the LDO output. The TC1303C is a 500-milliAmp synchronous-buck regulator and 300-milliAmp LDO with a power-good function on the LDO and dc-to-dc converter outputs. The TC1304 is a 500-milliAmp synchronous-buck regulator and 300-milliAmp LDO with power sequencing. Finally, the TC1313 is a 500-milliAmp synchronous-buck regulator and 300-milliAmp LDO.

The switching regulator is a synchronous buck dc-dc converter with a PWM oscillator operating at a fixed 2.0 MHz when the load is heavy. It offers a low-current operating mode, or pulse frequency operation (PFM), when the load is light in stand-by mode. The dc-dc regulator has adjustable and fixed-output voltage options, allowing the user to dial in the exact voltage needed or to use a fixed option to minimize the external part count.

The auxiliary linear LDO regulator can operate at loads of up to 300-milliAmps and has a typical dropout voltage of 137 milliVolts at a 200-milliAmp load. This allows the LDO to operate with minimum differential voltage. The LDO is stable with a single 1.0-microfarad ceramic capacitor on the output.

The devices are externally compensated and offer a number of protection features, including undervoltage lockout (UVLO), overtemperature protection and output short circuit protection. The TC1303/TC1313 devices offer individual shutdown controls for the two regulators, and an operating junction temperature range of -40 degrees Celsius to +125 degrees Celsius. The small thermally-enhanced package (10-lead, 3x3mm DFN) minimizes board space and allows for excess heat to be extracted from the package.

In the case of the TC1304, the power-good circuit in conjunction with the SHDN pin provides a power-sequencing function that requires the LDO output to be operating within specification before the switcher is allowed to activate. Conversely, the sequencing circuit turns off the switcher output prior to the LDO output when the device is shutting down.

The TC1303/TC1304 and TC1313 series provide a solution for applications like: computing (FPGA power source) and hand-held, battery-powered products (cell phones and MP3 players). For computers, the TC1303 family provides a solution for supplying dual output voltages for core voltage and I/O requirements. In addition, the power-good function can be used to signal when the power is within specific limits. Or, the TC1304 can be used to sequence power so that voltage is applied to one circuit before the other is powered up.

For hand-held battery-powered applications, the TC1303/TC1304 and TC1313 series provide a good fit because they have low quiescent current, power savings PFM mode and high conversion efficiency along with an auxiliary LDO for various applications. The major application is to supply low voltage core voltages and higher voltages for the I/O from a Lithium-Ion battery source.

All five devices are available today for sampling and volume production. Pricing for the TC1303B in 10,000-unit quantities is $1.28 in the 10-pin MSOP package and $1.34 in the 10-pin DFN package. All device packaging is lead (Pb) free.