Rainbow Electronics MAX5190 - Manual (Page 11)

MAX5187/MAX5190
8-Bit, 40MHz, Current/Voltage-Output DACs
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Outputs
The MAX5187 output is designed to supply full-scale
output currents of 1mA into 400
Ω loads in parallel with
a capacitive load of 5pF. The MAX5190 features inte-
grated 400
Ω resistors that restore the array current to
proportional, differential voltages of 400mV. These dif-
ferential output voltages can then be used to drive a
balun transformer or a low-distortion, high-speed oper-
ational amplifier to convert the differential voltage into a
single-ended voltage.
Applications Information
Static and Dynamic
Performance Definitions
Integral Nonlinearity
Integral nonlinearity (INL) (Figure 5a) is the deviation of
the values on an actual transfer function from either a
best-straight-line fit (closest approximation to the actual
transfer curve) or a line drawn between the endpoints
of the transfer function once offset and gain errors have
been nullified. For a DAC, the deviations are measured
every single step.
Differential Nonlinearity
Differential nonlinearity (DNL) (Figure 5b) is the differ-
ence between an actual step height and the ideal value
of 1LSB. A DNL error specification of less than 1LSB
guarantees no missing codes and a monotonic transfer
function.
Offset Error
Offset error (Figure 5c) is the difference between the
ideal and the actual offset point. For a DAC, the offset
point is the step value when the digital input is zero.
This error affects all codes by the same amount and
can usually be compensated by trimming.
Figure 5a. Integral Nonlinearity Figure 5b. Differential Nonlinearity
Figure 5c. Offset Error Figure 5d. Gain Error
0
2
1
4
3
7
6
5
000 010 001 011 100 101 110
AT STEP
011 (1/2 LSB )
AT STEP
001 (1/4 LSB )
111
DIGITAL INPUT CODE
ANALOG OUTPUT VALUE
0
2
1
4
3
6
5
000 010 001 011 100 101
DIFFERENTIAL LINEARITY
ERROR (-1/4 LSB)
DIFFERENTIAL
LINEARITY ERROR (+1/4 LSB)
1 LSB
1 LSB
DIGITAL INPUT CODE
ANALOG OUTPUT VALUE
0
2
1
3
000 010 001 011
ACTUAL
DIAGRAM
IDEAL DIAGRAM
ACTUAL
OFFSET
POINT
OFFSET ERROR
(+1 1/4 LSB)
IDEAL OFFSET
POINT
DIGITAL INPUT CODE
ANALOG OUTPUT VALUE
0
5
4
6
7
000 101 100 110 111
IDEAL DIAGRAM
GAIN ERROR
(-1 1/4 LSB)
IDEAL FULL-SCALE OUTPUT
ACTUAL
FULL-SCALE
OUTPUT
DIGITAL INPUT CODE
ANALOG OUTPUT VALUE