Description The TPS2140/41/50/51 is a USB1.0 and 2.0 specification compliant chip containing a dual currentlimiting power switch and adjustable low dropout regulator (LDO). Both the switch and the LDO limit the slew rate of the inrush current by controlling the power supply on. Unique dual current limit switch feature enables USB
peripherals, switch the output using high value capacitors while keeping the inrush current low. When the power supply is on, the switch current is limited to deliver less than 100 mA to the load capacitance. When the output voltage from the switch reaches about 93% of the input voltage, the switching power supply good output goes high and the switch current limit increases to 800 mA (minimum), at which point the high current load can be turned on. The higher current limit provides short circuit protection while allowing the peripheral to draw maximum current from the USB bus. The independent operation of switches and LDOs provides flexibility in DSP applications that require separate core and I/O voltages. For example, in a DSP application operating from a 3.3-V rail, the LDO can supply the DSP core voltage down to 0.9 volts, while switching powers 3.3 V (typ) to the DSP's I/O supply. The LDO power good output can be used to enable switching if supply sequencing is required.

Features Complete Power Management Solution for USB High Power Peripherals
250 mA low dropout regulator (LDO) with enable and 325 mA (typ) current limit
LDO supports 2.7 V to 5.5 V and 0.9 V to VIN, 3.3 V adjustable VOUT only 40m (typ) high side with dual MOSFET current limit undervoltage lockout and power good LDO and switch compatible with CMOS and TTL input enabled
85 Wei (typ) supply current
5 Ω (typ) standby current provides a 14-pin HTSSOP (the PowerPAD can be used over an ambient temperature range of ≤ 85°C to replace the TPS2148/58's 3.3V LDO using a 3.3-V switch and a 5-V switch

Applying high power USB peripherals
ADSL Modem Digital Camera and PC Camera
Zip drive speakers
Sequencing of DSP