Texas Instruments newest family of low dropout (LDO) voltage regulators offers designers of portable equipment a cost-effective alternative for accurate and efficient battery voltage regulation. Based on our high-performance TPS71xx 32 mV LDOs, the new TPS72xx series combines low dropout, micropower operation, and surface-mount packaging for at a very competitive price.
Like the TPS71xx, the TPS72xx features a PMOS pass transistor for delivering load current. Using a PMOS transistor instead of the more traditional PNP allows for dramatically lower dropout voltage and eliminates many of the undesirable characteristics of PNP LDO regulators. The TPS7250 5-V regulator has a maximum 85 mV dropout at 100 mA load.
The TPS72xx, designed to save battery power, has a typical quiescent current of only 155 µA independent of load. PNP-type LDO regulators which consume proportionally more power with increasing loads are less efficient. In dropout, PNP LDOs can draw 10 or more times the normal operating current requiring large start-up currents. Additional battery savings are possible with the TPS72xx in standby mode which reduces battery drain to under 0.5 µA.
The TPS72xx family includes three fixed-output-voltage options, and an adjustable device (see table) accurate to ±2% over the specified -40°C to 125°C operating range across full-rated line and load conditions. To save board area, they're designed to be stable with small surface-mount capacitors, typically 4.7 µF. They also feature a "power-good" pin which monitors the regulator's output voltage and can be used to drive power-on resets.
Suggested resale price per device in quanitities of 1,000:
TPS72xxQD : $0.90
See article Integrated LDO and supervisor
Vol 12, Summer, 1995