DALLAS Texas Instruments Inc.'s newest families of low-power boost converters and charge-pump triplers are designed to take full advantage of the entire life span of single- and dual-cell batteries used in personal digital assistants, cellular phones, and portable audio players and medical instruments.
The boost converters in the company's TPS6100x family allow designers to achieve a regulated 5-volt output with a continuous output current of at least 100 milliamps from a two-cell battery pack.
"These devices enable manufacturers to design smaller, more power-efficient portable applications that are able to use almost every drop of energy from the battery cells-even when the battery has already been drained below 1 volt," said Guenter Sporer, systems engineering manager for dc/dc converters at TI.
The converter ICs work from single- and dual-cell nickel-cadmium, nickel-metal-hydride or alkaline batteries, providing up to 250 mA in dual-cell systems. They are capable of starting up from voltages as low as 0.9 V and running from as little as 0.8 V, according to the company.
Features for prolonging battery life include a quiescent current of less than 50 microamps and a power-save mode that improves efficiency at low output currents. One adjustable and six fixed-output voltage options, ranging from 1.5 to 3.3 V, give designers flexibility in choosing system components. Conversion efficiency is greater than 90 percent, and stays high over a wide operating current range, TI said.
The TPS60140 and TPS60141 charge pumps are rated to supply a minimum continuous output current of 100 mA from a 2-V input. The converters deliver a 5-V output regulated within plus/minus 4 percent for a 1.8- to 3.3-V input. Special control circuitry keeps the output voltage ripple low-50 mV-across the entire current range. TI said that is half the ripple of competing solutions.
Integrated features of the TPS60140 include a low-battery comparator that issues a warning when battery voltage drops below an adjustable threshold. Alternatively, the TPS60141 also has a power-good comparator that goes active when the output voltage reaches 90 percent of its nominal value, making it easier to design a secure system power-up sequence.
Other features include a pulse-ski mode to extend battery life at light loads, and a shutdown mode that fully disconnects the load from the power source.
The TPS6100 converters are available in 10-pin micro small-outline packages for a suggested resale price of $2.13 each in quantities of 1,000.
The TPS60140 and TSP60141 are available in 20-pin thermally enhanced PowerPad TSSOPs. Their suggested resale price is $1.93 each in 1,000s. In addition, evaluation modules for both dc/dc converter families are now available for $50.
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EETInfo No. 618