x 0.1

= Percent_Error

x 10

3

x 10

3

2

n

10

3

SM74601

www.ti.com

SNOSBA5A – SEPTEMBER 2011 – REVISED APRIL 2013

LONG TERM STABILITY

Long-term stability refers to the fluctuation in output voltage over a long period of time (1000 hours). The

SM74601 features a typical long-term stability of 50 ppm over 1000 hours. The measurements are made using 5

units of each voltage option, at a nominal input voltage (5V), with no load, at room temperature.

EXPRESSION OF ELECTRICAL CHARACTERISTICS

Electrical characteristics are typically expressed in mV, ppm, or a percentage of the nominal value. Depending

on the application, one expression may be more useful than the other. To convert one quantity to the other one

may apply the following:

ppm to mV error in output voltage:

where

•

•

(4)

Bit error (1 bit) to voltage error (mV):

•

•

•

n is the number of bits

(5)

mV to ppm error in output voltage:

where

•

•

(6)

Voltage error (mV) to percentage error (percent):

where

•

•

(7)

PRINTED CIRCUIT BOARD and LAYOUT CONSIDERATIONS

To minimize the mechanical stress due to PC board mounting that can cause the output voltage to shift from its

initial value, mount the reference on a low flex area of the PC board, such as near the edge or a corner.

The part may be isolated mechanically by cutting a U shape slot on the PCB for mounting the device. This

approach also provides some thermal isolation from the rest of the circuit.

Bypass capacitors must be mounted close to the part. Mounting bypass capacitors close to the part will reduce

the parasitic trace components thereby improving performance.

Copyright © 2011–2013, Texas Instruments Incorporated

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