Datasheet

LP2952-N, LP2952A, LP2953, LP2953A

SNVS095D –MAY 2004–REVISED SEPTEMBER 2013

www.ti.com

Figure 36. Power Derating Curve for LP2953AMJ

Programming the Output Voltage

The regulator may be pin-strapped for 5V operation using its internal resistive divider by tying the Output and

Sense pins together and also tying the Feedback and 5V Tap pins together.

Alternatively, it may be programmed for any voltage between the 1.23V reference and the 30V maximum rating

using an external pair of resistors (see Figure 37). The complete equation for the output voltage is:

where

• V

REF

is the 1.23V reference and I

is the Feedback pin bias current (−20 nA typical). The minimum

recommended load current of 1 μA sets an upper limit of 1.2 MΩ on the value of R2 in cases where the

regulator must work with no load (see MINIMUM LOAD ). I

will produce a typical 2% error in V

OUT

which can

be eliminated at room temperature by trimming R1. For better accuracy, choosing R2 = 100 kΩ will reduce this

error to 0.17% while increasing the resistor program current to 12 μA. Since the typical quiescent current is

120 μA, this added current is negligible. (3)

* SeeApplication Hints

** Drive with TTL-low to shut down

Figure 37. Adjustable Regulator

Dropout Voltage

The dropout voltage of the regulator is defined as the minimum input-to-output voltage differential required for the

output voltage to stay within 100 mV of the output voltage measured with a 1V differential. The dropout voltage is

independent of the programmed output voltage.

Product Folder Links: LP2952-N LP2952A LP2953 LP2953A