MAX1258 Maxim Integrated Products, MAX1258 Datasheet - Page 40

• Manufacturer Part Number: MAX1258
• Description: Multichannel ADCs/DACs
• Manufacturer: Maxim Integrated Products

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12-Bit, Multichannel ADCs/DACs with FIFO,
Temperature Sensing, and GPIO Ports
Drive LDAC low to transfer the content of the input reg-
isters to the DAC registers. Drive LDAC permanently
low to make the DAC register transparent. The DAC
output typically settles from zero to full scale within ±1
LSB after 2µs. See Figure 14.
For best performance, use PC boards. Ensure that digi-
tal and analog signal lines are separated from each
other. Do not run analog and digital signals parallel to
one another (especially clock signals) or do not run
digital lines underneath the MAX1220–MAX1223/
MAX1257/MAX1258 package. High-frequency noise in
the AV
Bypass the AV
AGND, close to the AV
with a 0.1µF capacitor to DGND, close to the DV
Minimize capacitor lead lengths for best supply-noise
rejection. If the power supply is very noisy, connect a
10Ω resistor in series with the supply to improve power-
supply filtering.
Figure 13. GPIO Timing
Figure 14. LDAC Functionality
40
OUT_
LDAC
CS
GPIO INPUT/OUTPUT
______________________________________________________________________________________
DD
Layout, Grounding, and Bypassing
power supply may affect performance.
DD
supply with a 0.1µF capacitor to
DD
pin. Bypass the DV
t
GSU
LDAC Functionality
DD
t
LDACPWL
DD
supply
pin.
t
GOD
The MAX1220–MAX1223/MAX1257/MAX1258 thin QFN
packages contain an exposed pad on the underside of
the device. Connect this exposed pad to AGND. Refer to
the MAX1258EVKIT for an example of proper layout.
Integral nonlinearity (INL) is the deviation of the values
on an actual transfer function from a straight line. This
straight line can be either a best-straight-line fit or a line
drawn between the end points of the transfer function,
once offset and gain errors have been nullified. INL for
the MAX1220–MAX1223/MAX1257/MAX1258 is mea-
sured using the end-point method.
Differential nonlinearity (DNL) is the difference between
an actual step width and the ideal value of 1 LSB. A
DNL error specification of less than 1 LSB guarantees
no missing codes and a monotonic transfer function.
t
S
Differential Nonlinearity
Integral Nonlinearity
Definitions
±1 LSB