ISL21007 Datasheet, PDF (11/14 Pages) Intersil Corporation – Precision, Low Noise FGA™ Voltage References

ISL21007
0.01µF value can be increased for better load transient
response with little sacrifice in output stability.
V_IN = 3.0V
0.1µF
10µF
V_IN
V_O
ISL21007
GND
0.01µF
2kΩ
10µF
FIGURE 28. HANDLING HIGH LOAD CAPACITANCE
Turn-On Time
The ISL21007 devices have low supply current and thus the
time to bias up internal circuitry to final values will be longer
than with higher power references. Normal turn-on time is
typically 120µs. This is shown in Figure 10. Circuit design
must take this into account when looking at power up delays
or sequencing.
Temperature Coefficient
The limits stated for temperature coefficient (tempco) are
governed by the method of measurement. The overwhelming
standard for specifying the temperature drift of a reference is to
measure the reference voltage at two temperatures, take the
total variation, (V_HIGH – V_LOW), and divide by the temperature
extremes of measurement (T_HIGH – T_LOW). The result is
divided by the nominal reference voltage (at T = +25°C) and
multiplied by 10⁶ to yield ppm/°C. This is the “Box” method for
specifying temperature coefficient.
Output Voltage Adjustment
The output voltage can be adjusted up or down by 2.5% by
placing a potentiometer from Vout to ground, and connecting
the wiper to the TRIM pin. The TRIM input is high impedance,
so no series resistance is needed. The resistor in the
potentiometer should be a low tempco (<50ppm/°C) and the
resulting voltage divider should have very low tempco
<5ppm/°C. A digital potentiometer such as the ISL95810
provides a low tempco resistance and excellent resistor and
tempco matching for trim applications.
11
FN6326.1
April 12, 2007