Power Management ICs Combine Multiple Regulators

Aug 24, 2005 12:44 PM

Microchip Technology has introduced the TC1303/TC1304 and TC1313 Series of power management ICs that combine a synchronous buck switching regulator, low dropout regulator (LDO) and power-good function into single-chip solutions. These five new devices offer low-power and low-cost advantages for a variety of battery-operated and dual-output-voltage systems.

The five power management devices include:

• TC1303A. A 500-mA synchronous buck regulator and a 300-mA LDO with a power-good function on the dc-to-dc converter output.
• TC1303B. A 500-mA synchronous buck regulator and a 300-mA LDO with a power-good function on the LDO output.
• TC1303C. A 500-mA synchronous buck regulator and a 300-mA LDO with a power-good function on the LDO and dc-dc converter outputs.
• TC1304. A 500-mA synchronous buck regulator and a 300-mA LDO with power sequencing.
• TC1313. A 500-mA synchronous buck regulator and a 300-mA LDO.

These devices minimize board space because of the high-frequency operation of the buck converter, which reduces the size requirements of the external inductor and capacitor; the minimal external component requirement by the LDO and the small DFN package size.

The switching regulator is a synchronous buck dc-dc converter with a PWM oscillator operating at a fixed 2 MHz under heavy loads. It offers a low-current operating mode, or pulse frequency operation (PFM), when the load is light in standby mode. The dc-dc regulator has adjustable and fixed-output voltage options.

The auxiliary linear LDO regulator can operate at loads of up to 300 mA and has a typical dropout voltage of 137 mV at 200 mA. The LDO is stable with a single 1.0-µF ceramic capacitor on the output.

The devices are externally compensated and offer a number of protection features including undervoltage lockout, 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°C to +125°C. The small 10-lead, 3-mm × 3-mm thermally enhanced 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.

All five devices are available today. 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.

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