DEVICE INFORMATION

TPS7A45xx

TERMINAL FUNCTIONS

PIN

DESCRIPTION

NO.

NAME

Shutdown. SHDN is used to put the TPS7A45xx regulators into a low-power shutdown state. The output is off

when SHDN is pulled low. SHDN can be driven either by 5-V logic or open-collector logic with a pullup resistor.

1

SHDN

The pullup resistor is required to supply the pullup current of the open-collector gate, normally several

microamperes, and SHDN current, typically 3

µA. If unused, SHDN must be connected to V

the low-power shutdown state if SHDN is not connected.

Input. Power is supplied to the device through IN. A bypass capacitor is required on this pin if the device is more

than six inches away from the main input filter capacitor. In general, the output impedance of a battery rises with

frequency, so it is advisable to include a bypass capacitor in battery-powered circuits. A bypass capacitor

(ceramic) in the range of 1

µF to 10 µF is sufficient. The TPS7A45xx regulators are designed to withstand

2

IN

reverse voltages on IN with respect to ground and on OUT. In the case of a reverse input, which can happen if a

battery is plugged in backwards, the device acts as if there is a diode in series with its input. There is no reverse

current flow into the regulator, and no reverse voltage appears at the load. The device protects both itself and

the load.

Ground. The exposed thermal pad is connected to GND and must be soldered to the PCB for rated thermal

3

GND

performance.

Output. The output supplies power to the load. A minimum output capacitor (ceramic) of 10

µF is required to

4

OUT

prevent oscillations. Larger output capacitors are required for applications with large transient loads to limit peak

voltage transients.

Adjust. For the adjustable version only (TPS7A4501), this is the input to the error amplifier. ADJ is internally

5

ADJ

clamped to ±7 V. It has a bias current of 3

µA that flows into the pin. ADJ voltage is 1.21 V referenced to ground,

and the output voltage range is 1.21 V to 20 V.

Sense. For fixed-voltage versions (TPS7A4515, TPS7A4518, TPS7A4525, and TPS7A4533), SENSE is the

input to the error amplifier. Optimum regulation is obtained at the point where SENSE is connected to the OUT

between the regulator and the load. These may be eliminated by connecting SENSE to the output at the load as

5

SENSE

shown in Figure 32. Note that the voltage drop across the external PC traces adds to the dropout voltage of the

regulator. SENSE bias current is 600

µA at the rated output voltage. SENSE can be pulled below ground (as in a

dual supply system in which the regulator load is returned to a negative supply) and still allow the device to start

and operate.

Copyright © 2008, Texas Instruments Incorporated

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5

Product Folder Link(s): TPS7A45xx