LTC1657 LINER [Linear Technology], LTC1657 Datasheet - Page 7

• Manufacturer Part Number: LTC1657
• Description: Parallel 16-Bit Rail-to-Rail Micropower DAC
• Manufacturer: LINER [Linear Technology]

DEFI ITIO S
Resolution (n): Resolution is defined as the number of
digital input bits (n). It defines 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 zero. If the offset is negative, the output will remain
near 0V resulting in the transfer curve shown in Figure 1.
The offset of the part is measured at the code that corre-
sponds to the maximum offset specification:
Least Significant Bit (LSB): One LSB is the ideal voltage
difference between two successive codes.
Nominal LSBs:
DAC Transfer Characteristic:
G = 1 for X1/X2 connected to V
G = 2 for X1/X2 connected to GND
CODE = Decimal equivalent of digital input
(0 CODE 65535)
V
LSB = (V
LTC1657 LSB = 4.096V/65535 = 62.5 V
V
OS
OUT
U
= V
n
) that divide the full-scale range. Resolution does
OUT
G
NEGATIVE
FS
OFFSET
•
Figure 1. Effect of Negative Offset
– V
– [(Code)(V
VOLTAGE
REFHI REFLO
OUTPUT
U
OS
0V
)/(2
65536
FS
OS
–
n
): This is the output of the DAC
): Normally, the DAC offset is the
– 1) = (V
FS
)/(2
DAC CODE
OUT
n
CODE
– 1)]
FS
– V
OS
)/65535
1657 F01
REFLO
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 full scale
and the code corresponding to the maximum offset
specification. The INL error at a given input code is
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.
INL (In LSBs) = [V
(code/65535)]
V
the given input code
OUT
V
DNL = ( V
OUT
= The output voltage of the DAC measured at
= The measured voltage difference between
two adjacent codes
OUT
– LSB)/LSB
OUT
– V
OS
– (V
FS
– V
LTC1657
OS
)
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