MAX519ACSE データシートの表示（PDF） - Maxim Integrated
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MAX519ACSE Datasheet PDF : 16 Pages
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2-Wire Serial 8-Bit DACs with
Rail-to-Rail Outputs
OUT1
REF0
N.C.
REF1
SYSTEM GND
OUT0
N.C.
N.C.
GND
+5V
RF
CF
0.1µF
VDD
REF_
MAX517
MAX519
Figure 16. PC Board Layout for Minimizing MAX519 Crosstalk
(bottom view)
__________Applications Information
Power-Supply Bypassing and
Ground Management
Bypass VDD with a 0.1µF capacitor, located as close to
VDD and GND as possible. Careful PC board layout
minimizes crosstalk among DAC outputs, reference
inputs, and digital inputs. Figure 16 shows the suggest-
ed PC board layout to minimize crosstalk.
When using the MAX518 (or the MAX517/MAX519 with
VDD as the reference), you may want to add a noise fil-
ter to the VDD supply (Figure 17) or to the reference
input(s) (Figure 18), especially in noisy environments.
The reference input’s bandwidth exceeds 1MHz for AC
signals, so disturbances on the reference input can
easily affect the DAC output(s).
The maximum input current for a single reference input
is VREF/16kΩ = IREF (max). In Figure 17, choose RF so
that changes in the reference input current will have lit-
tle effect on the reference voltage. For example, with RF
= 6Ω, the maximum output error due to RF is given by:
6Ω x IREF (max) = 1.9mV or 0.1LSB
In Figure 18, there is a voltage drop across RF that
adds to the TUE. This voltage drop is due to the sum of
the reference input current (VREF/16kΩ maximum), sup-
ply current (6mA maximum), and the amplifier output
current (VREF/RLOAD). Choose RF to limit this voltage
drop to an acceptable value. For example, with a 10kΩ
load, you can limit the error due to RF to 0.5LSB
(9.8mV) by selecting RF so that:
RF = VRF / IRF ≤ 9.8mV / (5V / 16kΩ + 6mA +
5V / 10kΩ)
RF ≤ 1.4Ω
Figure 17. Reference Filter When Using VDD as a Reference
+5V
RF
CF
VDD
MAX518
0.1µF
Figure 18. VDD Filter When Using VDD as a Reference
14 ______________________________________________________________________________________
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