ISL60007_06 Datasheet, PDF (6/10 Pages) Intersil Corporation – Precision 2.50V, 1.08U-Watt, High Precision FGA Voltage References

ISL60007
Typical Performance Curves, 2.5V Reference V_IN = 3.0V, I_OUT = 0mA, T_A = 25°C
Unless Otherwise Specified (Continued)
140
120
100
80
60
40
20
0
1
100nF LOAD
10nF LOAD
1nF LOAD
NO
LOAD
10
100
1k
10k
FREQUENCY (Hz)
FIGURE 13. Z_OUT vs f vs C_L
100k
10s/DIV
FIGURE 14. V_OUT NOISE
Applications Information
FGA Technology
The ISL60007 series of voltage references use the floating
gate technology to create references with very low drift and
supply current. Essentially the charge stored on a floating
gate cell is set precisely in manufacturing. The reference
voltage output itself is a buffered version of the floating gate
voltage. The resulting reference device has excellent
characteristics which are unique in the industry: very low
temperature drift, high initial accuracy, and almost zero
supply current. Also, the reference voltage itself is not limited
by voltage bandgaps or zener settings, so a wide range of
reference voltages can be programmed (standard voltage
settings are provided, but customer-specific voltages are
available).
The process used for these reference devices is a floating
gate CMOS process, and the amplifier circuitry uses CMOS
transistors for amplifier and output transistor circuitry. While
providing excellent accuracy, there are limitations in output
noise level and load regulation due to the MOS device
characteristics. These limitations are addressed with circuit
techniques discussed in other sections.
Nanopower Operation
Reference devices achieve their highest accuracy when
powered up continuously, and after initial stabilization has
taken place. This drift can be eliminated by leaving the
power on continuously.
The ISL60007 is the first high precision voltage reference
with ultra low power consumption that makes it possible to
leave power on continuously in battery operated circuits. The
ISL60007 consumes extremely low supply current due to the
proprietary FGA technology. Supply current at room
temperature is typically 400nA which is 1 to 2 orders of
magnitude lower than competitive devices. Application
circuits using battery power will benefit greatly from having
an accurate, stable reference which essentially presents no
load to the battery.
In particular, battery powered data converter circuits that
would normally require the entire circuit to be disabled when
not in use can remain powered up between conversions as
shown in Figure 15. Data acquisition circuits providing 12 to
24 bits of accuracy can operate with the reference device
continuously biased with no power penalty, providing the
highest accuracy and lowest possible long term drift.
Other reference devices consuming higher supply currents
will need to be disabled in between conversions to conserve
battery capacity. Absolute accuracy will suffer as the device
is biased and requires time to settle to its final value, or, may
not actually settle to a final value as power on time may be
short.
V_IN = +3.0V
10µF
0.01µF
V_{IN VOUT}
ISL60007
GND
0.001µF - 0.01µF
SERIAL
BUS
REF IN
ENABLE
SCK
SDAT
12 TO 24-BIT
A/D CONVERTER
FIGURE 15.
6
FN8087.3
April 21, 2006