ltc1654cgn-trpbf Linear Technology Corporation, ltc1654cgn-trpbf Datasheet - Page 12

• Manufacturer Part Number: ltc1654cgn-trpbf
• Description: Ltc1654 - Dual 14-bit Rail-to-rail Dac In 16-lead Ssop Package
• Manufacturer: Linear Technology Corporation

LTC1654
DEFI ITIO S
Resolution (n): Resolution is defined as the number of
digital input bits (n). It is also the number of DAC output
states (2
not imply linearity.
Full-Scale Voltage (V
when all bits are set to 1.
Voltage Offset Error (V
voltage at the output when the DAC is loaded with all zeros.
The DAC can have a true negative offset, but because the
part is operated from a single supply, the output cannot go
below 0V. If the offset is negative, the output will remain
near 0V resulting in the transfer curve shown in Figure 3.
12
Therefore, the offset of the part is measured at low code k
V
OS
U
=
n
) that divide the full-scale range. Resolution does
V
NEGATIVE
OUT L
OFFSET
Figure 3. Effect of Negative Offset
VOLTAGE
⎛
⎝ ⎜
( ) –
OUTPUT
U
k
1
–
0V
2
n
k
( )(
FS
L
–
k
OS
2
L
): This is the output of the DAC
1
n
⎞
⎠ ⎟
): Normally, DAC offset is the
–
V
FS
1
DAC CODE
)
1654 F01
L
:
Least Significant Bit (LSB): One LSB is the ideal voltage
difference between two successive codes.
Nominal LSBs:
Zero-Scale Error (ZSE): The output voltage when the
DAC is loaded with all zeros. Since this is a single supply
part, this value cannot be less than 0V.
Integral Nonlinearity (INL): End-point INL is the maxi-
mum deviation from a straight line passing through the
end points of the DAC transfer curve. Because the part
operates from a single supply and the output cannot go
below zero, the linearity is measured between low code
k
calculated as follows:
Differential Nonlinearity (DNL): DNL is the difference
between the measured change and the ideal one LSB
change between any two adjacent codes. The DNL error
between any two codes is calculated as follows:
Digital Feedthrough: The glitch that appears at the analog
output caused by AC coupling from the digital inputs when
they change state. The area of the glitch is specified in
nV • s.
L
LSB = (V
LTC1654 LSB = 4.09575V/16383 = 250µV
INL = [V
V
DNL
∆V
and full scale. The INL error at a given input code is
OUT
OUT
= The output voltage of the DAC measured at the
= (∆V
= The measured voltage difference between
given input code
FS
two adjacent codes
OUT
– V
OUT
OS
– V
)/(2
– LSB)/LSB
OS
n
– (V
– 1) = (V
FS
– V
OS
FS
)(code/16383)]/LSB
– V
OS
)/16383
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