LP2953QML_16 Datasheet, PDF (15/26 Pages) Texas Instruments – Adjustable Micropower Low-Dropout Voltage Regulators

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LP2953QML, LP2953QML-SP
SNVS395C – NOVEMBER 2010 – REVISED APRIL 2013
Figure 30. Power Derating Curve for LP2953
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 31). The complete equation for the output voltage is:
(2)
where V_REF is the 1.23V reference and I_FB 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_FB will produce a typical 2% error in V_O 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.
* See Application Hints
** Drive with TTL-low to shut down
Figure 31. 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.
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