LP2950 Datasheet, PDF (12/32 Pages) National Semiconductor (TI) – Series of Adjustable Micropower Voltage Regulators

LP2950, LP2951
SLVS582I – APRIL 2006 – REVISED NOVEMBER 2014
7 Detailed Description
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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 V_TAP 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 V_TAP 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 V_OUT drops by 6% of its nominal value for whatever reasons – due to a drop in V_IN, 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
INPUT
+
Error
Amplifier
1.23-V Reference
OUTPUT
GND
12
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