LM4030 Datasheet, PDF (10/14 Pages) National Semiconductor (TI) – Ultra-High Precision Shunt Voltage Reference

V_REF2 = V_REF after temperature fluctuation.
The LM4030 features a low thermal hysteresis of 75 ppm
(typical) from -40°C to 125°C after 8 temperature cycles.
TEMPERATURE COEFFICIENT
Temperature drift is defined as the maximum deviation in out-
put voltage over the temperature range. This deviation over
temperature may be illustrated as shown in Figure 5.
shifts in VREF arise due to offsets between matched devices
within the regulation loop. Both passive and active devices
naturally experience drift over time and stress and tempera-
ture gradients across the silicon die also generate offset. The
LM4030 incorporates a dynamic offset cancellation scheme
which compensates for offsets developing within the regula-
tion loop. This gives the LM4030 excellent long-term stability
(40 ppm typical) and thermal hysteresis performance (75ppm
typical), as well as substantial immunity to PCB stress effects,
despite being packaged in a tiny SOT23.
EXPRESSION OF ELECTRICAL CHARACTERISTICS
Electrical characteristics are typically expressed in mV, ppm,
or a percentage of the nominal value. Depending on the ap-
plication, one expression may be more useful than the other.
To convert one quantity to the other one may apply the fol-
lowing:
ppm to mV error in output voltage:
30046320
FIGURE 5. Illustrative V_REF vs Temperature Profile
Temperature coefficient may be expressed analytically as the
following:
Where:
V_REF is in volts (V) and V_ERROR is in milli-volts (mV).
Bit error (1 bit) to voltage error (mV):
T_D = Temperature drift
V_REF = Nominal preset output voltage
V_{REF_MIN} = Minimum output voltage
temperature range
over
operating
V_{REF_MAX} = Maximum output voltage over operating
temperature range
ΔT = Operating temperature range.
The LM4030 features a low temperature drift of 10ppm (max)
to 30ppm (max), depending on the grade.
DYNAMIC OFFSET CANCELLATION AND LONG TERM
STABILITY
Aside from initial accuracy and drift performance, other spec-
ifications such as thermal hysteresis and long-term stability
can affect the accuracy of a voltage reference, especially over
the lifetime of the application. The reference voltage can also
shift due to board stress once the part is mounted onto the
PCB and during subsequent thermal cycles. Generally, these
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).
Voltage error (mV) to percentage error (percent):
Where:
V_REF is in volts (V) and V_ERROR is in milli-volts (mV).
www.national.com
10