Datasheet
x 0.1
V
REF
= Percent_Error
V
ERROR
x 10
3
V
REF
= ppm
ERROR
V
ERROR
x 10
3
V
REF
2
n
= V
ERROR
= V
ERROR
10
3
V
REF
x ppm
ERROR
LM4132
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SNVS372C –AUGUST 2005–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 LM4132
features a typical long-term stability of 50ppm 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
• V
REF
is in volts (V) and V
ERROR
is in milli-volts (mV). (4)
Bit error (1 bit) to voltage error (mV):
(5)
V
REF
is in volts (V), V
ERROR
is in milli-volts (mV), and n is the number of bits.
mV to ppm error in output voltage:
Where
• V
REF
is in volts (V) and V
ERROR
is in milli-volts (mV). (6)
Voltage error (mV) to percentage error (percent):
Where
• V
REF
is in volts (V) and V
ERROR
is in milli-volts (mV). (7)
PRINTED CIRCUIT BOARD and LAYOUT CONSIDERATIONS
References in SOT packages are generally less prone to PC board mounting than devices in Small Outline
(SOIC) packages. 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.
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