MX7534 Просмотр технического описания (PDF) - Maxim Integrated
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MX7534 Datasheet PDF : 16 Pages
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Microprocessor-Compatible,
14-Bit DACs
VIN
R1
100Ω
VDD
1 19
R2, 33Ω
2
A0 16
A1 15
18
CS
WR 17
REF
RFB
3
IOUT
MX7534
AGNDS
4
AGNDF
D7–D0 DGND VSS
5
7–14
6 20
C1
33pF
A1
+
R6
20k
R7
20k
R5 10k
R8, 5k,10% A2
+
VO
INPUT
DATA
Figure 5a. Bipolar Operation
ANALOG
GROUND
Gain Adjustment
(Figures 6a and 6b)
1) Load DAC register with all 1s.
( ) 2) Trim potentiometer R3 so that VOUT = -
16383
16384
VIN
Low-Leakage Configuration
Leakage current in the DAC flowing into the IOUT line
can cause gain, linearity, and offset errors. Leakage is
worse at high temperatures.
Negatively bias VSS for a high-temperature, low-leakage
configuration.
Dynamic Considerations
In static or DC applications, the output amplifier’s AC
characteristics are not critical. In higher-speed applica-
tions, where either the reference input is an AC signal
or the DAC output must quickly settle to a new pro-
grammed value, the output op amp’s AC parameters
must be considered.
Another error source in dynamic applications is the par-
asitic signal coupling from the REF terminal to IOUT.
This is normally a function of board layout and lead-to-
lead package capacitance. Signals can also be inject-
ed into the DAC outputs when the digital inputs are
switched. This digital feedthrough depends on circuit-
board layout and on-chip capacitive coupling. Minimize
layout-induced feedthrough with guard traces between
digital inputs, REF, and DAC outputs.
VIN
R1
VDD R2 10Ω
20Ω
2
1 26 3
C1
LDAC 23 REFF REFS RFB
33pF
CSMSB 22
4
IOUT
R6
20k
R7
20k
R5
10k
25
WR
MX7535
A1
AGNDS +
CSLSB 24
AGNDF 5
D13–D0 DGND VSS 6
R8, 5k,10% A2
+
VO
8–21
7 27
INPUT
DATA
Figure 5b. Bipolar Operation
ANALOG
GROUND
Table 3. MX7535 Logic States
CSMSB CSLSB LDAC WR
FUNCTION
0
1
1
0 Load MS Input Register
1
0
1
0 Load LS Input Register
0
0
1
0
Load LS and MS Input
Registers
1
1
0
X
Load DAC Register
from Input Register
0
0
0
0
All registers are
transparent.
1
1
1
X No operation
X
X
1
1 No operation
Note: X = Don’t Care.
Table 4. Offset Binary Bipolar Code Table
BINARY NUMBER IN
DAC REGISTER
MSB
11 1111
1111
LSB
1111
10 0000
0000 0001
10 0000
0000 0000
01 1111
1111 1111
00 0000
0000 0000
Analog Output
(VOUT)
( ) +VIN
8191
8192
( ) +VIN
1
8192
0
( ) -VIN
1
8192
( ) -VIN
8192
8192
= -VIN
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