ISL21010_15 Datasheet, PDF (33/35 Pages) Intersil Corporation – Micropower Voltage Reference

ISL21010
Applications Information
Micropower Operation
The ISL21010 consumes very low supply current due to the
proprietary bandgap technology. Low noise performance is
achieved using optimized biasing techniques. Supply current is
typically 48µA and noise in the 0.1Hz to 10Hz bandwidth is
58µV_P-P to 100µV_P-P (V_OUT = 2.048V, 3.0V and 3.3V) benefiting
precision, low noise portable applications such as handheld
meters and instruments.
Data Converters in particular can utilize the ISL21010 as an
external voltage reference. Low power DAC and ADC circuits will
realize maximum resolution with lowest noise. The device
maintains output voltage during conversion cycles with fast
response, although it is helpful to add an output capacitor,
typically 1µF.
Board Mounting Considerations
For applications requiring the highest accuracy, board mounting
location should be reviewed. The device uses a plastic SOIC
package, which will subject the die to mild stresses when the
Printed Circuit (PC) board is heated and cooled, slightly changing
the shape. Placing the device in areas subject to slight twisting
can cause degradation of the accuracy of the reference voltage
due to these die stresses. It is normally best to place the device
near the edge of a board, or the shortest side, as the axis of
bending is most limited at that location. Mounting the device in a
cutout also minimizes flex. Obviously mounting the device on
flexprint or extremely thin PC material will likewise cause loss of
reference accuracy.
Board Assembly Considerations
Bandgap references provide high accuracy and low temperature
drift but some PC board assembly precautions are necessary.
Normal output voltage shifts of 100µV to 4mV can be expected
with Pb-free reflow profiles or wave solder on multilayer FR4 PC
boards. Precautions should be taken to avoid excessive heat or
extended exposure to high reflow or wave solder temperatures,
this may reduce device initial accuracy.
Noise Performance and Reduction
The recommended capacitive load range for the ISL21010 is from
0.1µF to 10.0µF (0.22µF minimum required for 1.024V option) to
ensure stability and best transient performance. Parallel 0.1µF
(0.22µF for 1.024V) and 10µF capacitors can be used to optimize
performance as well. The noise specification stated in the
Electrical Specification tables (starting on page 4) is for 0.1µF
(0.22µF for 1.024V option) capacitive load, and larger values will
reduce the output noise level.
Typical Application Circuit
VIN
2.1V – 5.5V
0.1µF
10µF
ISL21010
VIN
VOUT
GND
0.1µF - 10µF
VOUT
SENSE
LOAD
FIGURE 138. KELVIN SENSED LOAD
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FN7896.3
January 8, 2015