ISL60002DIH312Z Intersil, ISL60002DIH312Z Datasheet - Page 28

• Manufacturer Part Number: ISL60002DIH312Z
• Description: REF 1.25V LOW POWER FGA, SOT-23-3
• Manufacturer: Intersil

Specifications of ISL60002DIH312Z

• Topology: Series
• Input Voltage: 2.7V To 5.5V
• Reference Voltage Tolerance: 5mV
• Voltage Reference Case Style: SOT-23
• No. Of Pins: 3
• Operating Temperature Range: -40°C
• Temperature Coefficient: 20ppm/°C
• Reference Voltage: 1.25V
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Applications Information
FGA Technology
The ISL60002 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 ISL60002 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
ISL60002 consumes extremely low supply current due to the
proprietary FGA technology. Supply current at room
temperature is typically 350nA 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 99. 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.
28
ISL60002
Board Mounting Considerations
For applications requiring the highest accuracy, board
mounting location should be reviewed. Placing the device in
areas subject to slight twisting can cause degradation of the
accuracy of the reference voltage due to 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. Obviously mounting the device on flexprint or
extremely thin PC material will likewise cause loss of
reference accuracy.
Noise Performance and Reduction
The output noise voltage in a 0.1Hz to 10Hz bandwidth is
typically 30µV
Performance Curves. The noise measurement is made with
a bandpass filter made of a 1 pole high-pass filter with a
corner frequency at 0.1Hz and a 2-pole low-pass filter with a
corner frequency at 12.6Hz to create a filter with a 9.9Hz
bandwidth. Noise in the 10kHz to 1MHz bandwidth is
approximately 400µV
as shown in Figure 100. These noise measurements are
made with a 2 decade bandpass filter made of a 1 pole high-
pass filter with a corner frequency at 1/10 of the center
frequency and 1-pole low-pass filter with a corner frequency
at 10 times the center frequency. Figure 100 also shows the
noise in the 10kHz to 1MHz band can be reduced to about
50µV
the 1kHz to 100kHz band can be further reduced using a
0.1µF capacitor on the output, but noise in the 1Hz to 100Hz
band increases due to instability of the very low power
amplifier with a 0.1µF capacitance load. For load
capacitances above 0.001µF the noise reduction network
shown in Figure 101 is recommended. This network reduces
noise significantly over the full bandwidth. As shown in
Figure 100, noise is reduced to less than 40µV
to 1MHz using this network with a 0.01µF capacitor and a
2kΩ resistor in series with a 10µF capacitor.
V
IN
P-P
= +3.0V
using a 0.001µF capacitor on the output. Noise in
GND
ISL60002
P-P
V
IN
. This is shown in the plot in the Typical
V
0.001µF–0.01µF
OUT
P-P
FIGURE 99.
with no capacitance on the output,
SERIAL
BUS
10µF
0.01µF
REF IN
ENABLE
SCK
SDAT
A/D CONVERTER
12 to 24-BIT
P-P
August 1, 2006
from 1Hz
FN8082.7