Datasheet

MAX6126
Ultra-High-Precision, Ultra-Low-Noise,
Series Voltage Reference
15
Maxim Integrated
racy is needed. The MAX6126 has the same type of
Kelvin connection to cancel drops in the ground return
line. Connect the load to ground and bring a connection
from GNDS to exactly the same point.
Applications Information
Precision Current Source
Figure 2 shows a typical circuit providing a precision
current source. The OUTF output provides the bias cur-
rent for the bipolar transistor. OUTS and GNDS sense
the voltage across the resistor and adjust the current
sourced by OUTF accordingly. For even higher preci-
sion, use a MOSFET to eliminate base current errors.
High-Resolution DAC and Reference from
a Single Supply
Figure 3 shows a typical circuit providing the reference
for a high-resolution, 16-bit MAX541 D/A converter.
Temperature Coefficient vs. Operating
Temperature Range for a 1 LSB Maximum
Error
In a data converter application, the reference voltage of
the converter must stay within a certain limit to keep the
error in the data converter smaller than the resolution
limit through the operating temperature range. Figure 4
shows the maximum allowable reference voltage tem-
perature coefficient to keep the conversion error to less
than 1 LSB, as a function of the operating temperature
range (T
MAX
- T
MIN
) with the converter resolution as a
parameter. The graph assumes the reference voltage
temperature coefficient as the only parameter affecting
accuracy.
In reality, the absolute static accuracy of a data con-
verter is dependent on the combination of many para-
meters such as integral nonlinearity, differential
nonlinearity, offset error, gain error, as well as voltage
reference changes.
OUTF
I
SOURCE
R
OUTS
V
OUT(NOMINAL)
/ R = I
SOURCE
IN
GND
GNDS
MAX6126
Figure 2. Precision Current Source
OUTF
OUTS
IN
GND
GNDS
MAX6126
OUT
REF
ANALOG
OUTPUT
V
DD
3V SUPPLY
GND
MAX541
DAC
Figure 3. 14-Bit High-Resolution DAC and Positive Reference
from a Single 3V Supply