The industry's first family of products combining 3.3-volt low-dropout (LDO) regulators and dual power switches in a single chip for use in Universal Serial Bus and portable applications is now available from Texas Instruments (TI). These new LDO-switch combos provide a complete power management solution for USB bus-powered hub and peripheral products, such as keyboards with mouse extensions or smart card sockets, as well as for personal digital assistants (PDAs) and other battery-powered systems. These integrated devices save up to 60 percent in board space over today's typical two-chip solutions, while simplifying the design and reducing system costs and time to market. TI's new TPS2145 LDO-Switch family offers flexible combinations of dual-port protected switching and LDO voltage regulation for USB-powered and portable systems. The devices provide 3.3-V regulated output from a 5.0-V input with 200 milliamps (mA) of continuous current for USB controllers and other circuitry.

Select devices are designed to support either USB peripherals or USB hubs and offer the appropriate switch configurations, simplifying the system designer's job of meeting the USB operating current requirements. In addition, the family includes both active-high and active-low enable versions of each switch configuration. An adjustable LDO option with 1.0- to 3.3-V output from a 2.9- to 5.5-V input is available for use in portable systems. Device options offer both ganged and independent USB port power control and offer thermal and short-circuit protection for both the LDO and switches. Moreover, controlled rise and fall times minimize current surges at power-up and during "hot" plugging of USB downstream devices.

"TI's new TPS2145 LDO-switch combos provide a complete power management solution for today's highly integrated USB hubs and peripherals, helping to meet the standby (500uA), start-up (100mA) and operating current specifications (500mA)," said Landa Pham, TI product marketing manager. "Developers of PDAs and other portable products can also use the LDO-switch combos for power segmentation to save battery life." The new TPS2145 devices augment TI's comprehensive USB portfolio, the industry's most complete line of USB IC products. TI's portfolio includes the TUSBxxx hub, peripheral, and streaming audio controllers; the TPS204xA/5xA power switches; the TPS788xx family of low-noise LDOs; the SN75240 transient suppressor; and the TPS207x family of power controllers for 4-port USB hub boxes.

Texas Instruments Incorporated, Semiconductor Group, SC-01130, Literature Response Center, P.O. Box 954, Santa Clarita, CA 91380. Phone: 800-477-8924, ext. 4500

The new LDO-switch combo from TI is well focused on the portable and USB product markets. It makes sure that you can shrink your design bill of materials and control voltages. This new design offers two power-distribution switches and an adjustable (TPS2145) or fixed (TPS2147) LDO, incorporated in one small package. It also provides a power management solution that saves up to 60% in board space over typical implementations.

USB 2.0 is here to stay and TI designed these devices to meet USB 2.0 bus-powered hub requirements. They also allow core and I/O voltage sequencing in DSP applications, or power segmentation in portable equipment.

As with most low voltage digital circuits it is important to have load regulation because most digital circuits do not deal well with voltage transients - so the LDO's transient response must be minimized. TI uses an internal charge pump to provide the gate drive controlling the power-switch rise times and fall times, thereby minimizing current surges during switching. And, the charge pump requires no external components.

TPS2145 LDO-Switch Combo products are now available from TI and its authorized distributors. Packages include 8- and 10-pin MSOP PowerPad options that reduce space and complexity while providing outstanding thermal protection. Prices are as follows:

Device	LDO Output	Switch Enables	Target Applications	Price (1,000)
TPS2145	1 to 3.3V	Low	Portable	$1.08
TPS2147	3.3 V	Low	Portable	$1.00
TPS2148	3.3 V	Low	USB peripheral	$0.93
TPS2149	3.3 V	Low	USB hub	$0.86
TPS2155	1 to 3.3V	High	Portable	$1.08
TPS2157	3.3 V	High	Portable	$1.00
TPS2158	3.3 V	High	USB peripheral	$0.93
TPS2159	3.3 V	High	USB hub	$0.86

Data sheet available at: http://focus.ti.com/