Datasheet

TPS7A45xx
www.ti.com SLVS720D –JUNE 2008–REVISED AUGUST 2011
DEVICE INFORMATION
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. SHDNcan be driven by 5-V logic, 3-V logic or open-collector logic with a pullup
1 SHDN resistor. 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
IN
. The device is in
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.
3 GND For the KTT package, the exposed thermal pad is connected to GND and must be soldered to the PCB for rated
thermal 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
pin of the regulator. In critical applications, small voltage drops are caused by the resistance (R
P
) of PC traces
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.
6 GND Ground. DCQ package only.
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