LP2950 datasheet(12/26 Pages) TI

12 / 26 page

1.23-V Reference

Error

Amplifier

GND

OUTPUT

INPUT

LP2950, LP2951

SLVS582I – APRIL 2006 – REVISED NOVEMBER 2014

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7 Detailed Description

7.1 Overview

The LP2950 and LP2951 devices are bipolar, low-dropout voltage regulators that can accommodate a wide input

supply-voltage range of up to 30 V. The easy-to-use, 3-pin LP2950 is available in fixed-output voltages of 5 V,

3.3 V, and 3 V. However, the 8-pin LP2951 device is able to output either a fixed or adjustable output from the

same device. By tying the OUTPUT and SENSE pins together, and the FEEDBACK and VTAP pins together, the

LP2951 device outputs a fixed 5 V, 3.3 V, or 3 V (depending on the version). Alternatively, by leaving the SENSE

and VTAP pins open and connecting FEEDBACK to an external resistor divider, the output can be set to any

value between 1.235 V to 30 V.

The 8-pin LP2951 device also offers additional functionality that makes it particularly suitable for battery-powered

applications. For example, a logic-compatible shutdown feature allows the regulator to be put in standby mode

for power savings. In addition, there is a built-in supervisor reset function in which the ERROR output goes low

when VOUT drops by 6% of its nominal value for whatever reasons – due to a drop in VIN, current limiting, or

thermal shutdown.

The LP2950 and LP2951 devices are designed to minimize all error contributions to the output voltage. With a

tight output tolerance (0.5% at 25°C), a very low output voltage temperature coefficient (20 ppm typical),

extremely good line and load regulation (0.3% and 0.4% typical), and remote sensing capability, the parts can be

used as either low-power voltage references or 100-mA regulators.

7.2 LP2950 Functional Block Diagram

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LP2950 Datasheet(PDF) 12 Page - Texas Instruments