Datasheet

TPS70245, TPS70248

TPS70251, TPS70258

TPS70202

www.ti.com

SLVS286E –JUNE 2000–REVISED DECEMBER 2009

Detailed Description

The TPS702xx low dropout regulator family provides dual regulated output voltages with independent enable

functions. These devices provide fast transient response and high accuracy with small output capacitors, while

drawing low quiescent current. Other features are integrated SVS (power-on reset, RESET) and power good

(PG1, PG2) that monitor output voltages and provide logic output to the system. These differentiated features

provide a complete power solution.

The TPS702xx, unlike many other LDOs, features very low quiescent current that remains virtually constant even

with varying loads. Conventional LDO regulators use a pnp pass element, the base current of which is directly

proportional to the load current through the regulator (I

= I

/β). The TPS702xx uses a PMOS transistor to pass

current; the gate of the PMOS is voltage-driven, so operating current is low and stable over the full load range.

Pin Functions

Enable (EN1, EN2)

The EN terminals are inputs that enable or shut down each respective regulator. If EN is at a voltage high signal,

the respective regulator is in shutdown mode. When EN goes to voltage low, the respective regulator is enabled.

Power-Good (PG1, PG2)

The PG terminals are open drain, active high output terminals that indicate the status of each respective

regulator. When V

OUT1

reaches 95% of its regulated voltage, PG1 goes to a high impedance state. When V

OUT2

reaches 95% of its regulated voltage, PG2 goes to a high impedance state. Each PG goes to a low impedance

state when its respective output voltage is pulled below 95% (that is, goes to an overload condition) of its

regulated voltage. The open drain outputs of the PG terminals require a pull-up resistor.

Manual Reset Pin

MR is an active low input terminal used to trigger a reset condition. When MR is pulled to logic low, a POR

(RESET) occurs. The terminal has a 6μA pull-up current to V

IN1

Sense (V

SENSE1

, V

SENSE2

)

The sense terminals of fixed-output options must be connected to the regulator outputs, and the connection

should be as short as possible. Internally, the sense terminal connects to high-impedance, wide-bandwidth

amplifiers through a resistor-divider network and noise pickup feeds through to the regulator output. It is essential

to route the sense connection in such a way as to minimize or avoid noise pickup. Adding RC networks between

sense terminals and V

OUT

terminals to filter noise is not recommended because these networks can cause the

regulators to oscillate.