_______________General Description
The MX7837/MX7847 are dual, 12-bit, multiplying, volt-
age-output digital-to-analog converters (DACs). Each
DAC has an output amplifier and a feedback resistor.
The output amplifier is capable of developing 10V
across a 2k
load. The amplifier feedback resistor is
internally connected to V
OUT
on the MX7847. No exter-
nal trims are required to achieve full 12-bit performance
over the entire operating temperature range.
The MX7847 has a 12-bit parallel data input, whereas
the MX7837 operates with a double-buffered 8-bit-bus
interface that loads data in two write operations. All
logic signals are level triggered and are TTL and CMOS
compatible. Fast timing specifications make these
DACs compatible with most microprocessors.
________________________Applications
Small Component-Count Analog Systems
Digital Offset/Gain Adjustments
Industrial Process Control
Function Generators
Automatic Test Equipment
Automatic Calibration
Machine and Motion Control Systems
Waveform Reconstruction
Synchro Applications
____________________________Features
o
Two 12-Bit Multiplying DACs with Buffered
Voltage Output
o
Specified with 12V or 15V Supplies
o
No External Adjustments Required
o
Fast Timing Specifications
o
24-Pin DIP and SO Packages
o
12-Bit Parallel Interface (MX7847)
8-Bit + 4-Bit Interface (MX7837)
______________Ordering Information
Ordering Information continued on last page.
* Contact factory for availability and processing to MIL-STD-883.
MX7837/MX7847
Complete, Dual, 12-Bit
Multiplying DACs
________________________________________________________________
Maxim Integrated Products
1
24
23
22
21
20
19
18
17
16
15
1
2
3
4
5
6
7
8
9
10
11
12
13
DB0/DB8
DB1/DB9
DB2/DB10
DB3/DB11
DB4
DB5
DB6
DB7
A0
A1
LDAC
WR
R
FBB
DGND
V
REFB
V
OUTB
AGNDB
V
SS
V
DD
AGNDA
V
OUTA
V
REFA
R
FBA
CS
DIP/SO
TOP VIEW
MX7837
14
MX7847 on last page.
_________________Pin Configurations
4
8
12
DAC LATCH A
MSB
INPUT
LATCH
LSB
INPUT
LATCH
DAC A
4
8
12
DAC LATCH B
MSB
INPUT
LATCH
LSB
INPUT
LATCH
DAC B
CONTROL
LOGIC
LDAC
CS
WR
A0
A1
DB7
DB0
V
REFB
V
REFA
R
FBA
V
OUTA
AGNDA
R
FBB
V
OUTB
AGNDB
DGND
V
SS
V
DD
MX7837
MX7847 on last page.
_________Typical Operating Circuits
Call toll free 1-800-998-8800 for free samples or literature.
19-0158; Rev 0; 7/93
PART
TEMP. RANGE
PIN-PACKAGE
MX7837
JN
0C to +70C
24 Narrow Plastic DIP
MX7837KN
0C to +70C
24 Narrow Plastic DIP
MX7837JR
0C to +70C
24 Wide SO
MX7837KR
0C to +70C
24 Wide SO
MX7837C/D
0C to +70C
Dice*
ERROR
(LSB)
1
1/2
1
1/2
1
MX7837/MX7847
Complete, Dual, 12-Bit
Multiplying DACs
2
_______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
V
DD
to DGND, AGNDA, AGNDB ............................-0.3V to +17V
V
SS
to DGND, AGNDA, AGNDB (Note 1) ..............+0.3V to -17V
V
REFA
, V
REFB
to AGNDA, AGNDB .. (V
SS
- 0.3V) to (V
DD
+ 0.3V)
AGNDA, AGNDB to DGND.........................-0.3V to (V
DD
+ 0.3V)
V
OUTA
, V
OUTB
to AGNDA, AGNDB .....(V
SS
- 0.3V) to (V
DD
+ 0.3V)
R
FBA
, R
FBB
to AGNDA, AGNDB .......(V
SS
- 0.3V) to (V
DD
+ 0.3V)
Digital Inputs to DGND ...............................-0.3V to (V
DD
+ 0.3V)
Continuous Power Dissipation (T
A
= +70C)
Narrow Plastic DIP (derate 13.33mW/C above +70C)....1067mW
SO (derate 11.76mW/C above +70C) .........................941mW
Narrow CERDIP (derate 12.50mW/C above +70C) ..1000mW
Operating Temperature Ranges:
MX78_7J_/K_ ........................................................0C to +70C
MX78_7A_/B_ .................................................. -40C to +85C
MX78_7SQ/TQ ............................................... -55C to +125C
Storage Temperature Range ............................ -65C to +150C
Lead Temperature (soldering, 10sec) .............................+300C
ELECTRICAL CHARACTERISTICS
(V
DD
= 11.4V to 16.5V, V
SS
= -11.4V to -16.5V, AGNDA = AGNDB = DGND = 0V, V
REFA
= V
REFB
= +10V, R
L
= 2k
, C
L
= 100pF,
V
OUT
connected to R
FB
(MX7837), T
A
= T
MIN
to T
MAX
, unless otherwise noted.) (Note 2)
Note 1:
If V
SS
is open-circuited with V
DD
and either AGND applied, the V
SS
pin will float positive exceeding the
Absolute Maximum Ratings.
If this possibility exists, a Schottky diode connected between V
SS
and GND ensures the maximum ratings will be observed.
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
PARAMETER
SYMBOL
MIN
TYP
MAX
UNITS
4
2
Differential Nonlinearity
DNL
1
LSB
Relative Accuracy
INL
1/2
LSB
3
Zero-Code Offset Error
5
mV
5
2
Resolution
N
12
Bits
1
Loaded with all 0s,
tempco =
5V/C typ
CONDITIONS
MX78_7J/A
T
A
= +25C
Guaranteed monotonic
MX78_7K/B/T
MX78_7K/B
MX78_7S/T
MX78_7J/A/S
MX78_7K/B/T
MX78_7J/A/S
T
A
= +25C
MX78_7J/A/S
7
Gain Error
Loaded with all 1s,
tempco = 2ppm
of FSR/C typ
T
A
= T
MIN
to T
MAX
MX78_7K/B/T
4
LSB
V
REF
Input Resistance
8
10
13
k
V
REFA
, V
REFB
Resistance
Matching
0.5
3
%
Input High Voltage
2.4
V
Input Low Voltage
0.8
Input Current
Digital inputs at 0V and V
DD
1
A
Input Capacitance (Note 4)
8
pF
DC Output Impedance
0.2
Short-Circuit Current
V
OUT
connected to AGND
15
mA
V
INH
T
A
= T
MIN
to T
MAX
V
INL
STATIC PERFORMANCE (Note 3)
REFERENCE INPUTS
DIGITAL INPUTS
ANALOG OUTPUTS
MX7837/MX7847
Complete, Dual, 12-Bit
Multiplying DACs
_______________________________________________________________________________________
3
PARAMETER
SYMBOL
MIN
TYP
MAX
UNITS
CONDITIONS
0.01
0.01
0.01
Power-Supply Rejection
0.01
% per %
Voltage-Output Settling
Time
t
S
Settling time to within 1/2LSB of final DAC value;
DAC latch alternately loaded will all 0s and all 1s
4
s
Slew Rate
7
V/s
Digital-to Analog Glitch
Impulse
Q
DAC latch alternately loaded with 01...11 and
10...00
60
nV-s
Channel-to-Channel Isolation
(V
REFA
to V
OUTB
,
V
REFB
to V
OUTA
)
V
REF
= 20p-p, 10kHz sine wave, Alternate DAC
Latch Loaded with all 0s
-95
dB
Multiplying Feedthrough
Error
-90
dB
Unity-Gain Small-Signal
Bandwidth
THD
1
MHz
Full-Power Bandwidth
125
kHz
Total Harmonic Distortion
V
REF
= 6V
RMS
, 1kHz, DAC latch loaded with all 1s
-88
dB
Digital Crosstalk
Code transition from all 0s to all 1s; see
Typical
Operating Characteristics graphs
10
nV-s
Output Noise Voltage at
+25C (0.1Hz to 10Hz)
Amplifier noise and Johnson noise of R
FB
2
V
RMS
V
DD
Range
V
DD
11.4
16.5
V
Positive Supply Current
I
DD
5
10
mA
Output unloaded
Negative Supply Current
I
SS
4
6
mA
Output unloaded
V
SS
Range
V
SS
-11.4
-16.5
V
V
REF
= 20V
p-p
S
ine wave, DAC latch loaded with
all 1s
V
REF
= 100mV
p-p
sine wave, DAC latch loaded
with all 1s
V
REF_
= 20V
p-p
, 10kHz sine wave, latches loaded
with all 0s
V
SS
= -12V 5%, V
REF
= 8.9V
V
DD
= 12V 5%, V
REF
= -8.9V
V
SS
= -15V 5%, V
REF
= 10V
V
DD
= 15V 5%, V
REF
= -10V
Gain/
V
DD
Gain/
V
SS
Gain/
V
SS
Gain/
V
DD
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= 11.4V to 16.5V, V
SS
= -11.4V to -16.5V, AGNDA = AGNDB = DGND = 0V, V
REFA
= V
REFB
= +10V, R
L
= 2k
, C
L
= 100pF,
V
OUT
connected to R
FB
(MX7837), T
A
= T
MIN
to T
MAX
, unless otherwise noted.) (Note 1)
Note 2:
The analog outputs can swing to within 2.5V of the supply rails. Hence, for good linearity towards full-scale, |V
REFA
| and |V
REFB
| must
be at least 2.5V lower than V
DD
and |V
SS
|. Tests done with supply voltages below 12.5V are done with V
REFA
= V
REFB
= 8.9V.
Note 3:
Static performance tested at V
DD
= +15V, V
SS
= -15V. Performance over supplies guaranteed by PSRR test.
Note 4:
Guaranteed by design.
POWER REQUIREMENTS
AC CHARACTERISTICS
MX7837/MX7847
Complete, Dual, 12-Bit
Multiplying DACs
4
_______________________________________________________________________________________
__________________________________________Typical Operating Characteristics
(T
A
= +25C, V
DD
= 15V, V
SS
= -15V, R
L
= 2k
, C
L
= 100pF, unless otherwise noted)
25
0
10
1k
10k
OUTPUT VOLTAGE SWING
vs. RESISTIVE LOAD
10
20
LOAD RESISTANCE (
)
V
OUT
(V
p-p
)
100
15
5
V
REF
= 20V
p-p
at 1kHz
0
10
100k
NOISE SPECTRAL DENSITY
100
300
FREQUENCY (Hz)
NOISE SPECTRAL DENSITY (nV/ Hz)
200
100
1k
10k
V
REF
= 0V
DAC CODE = 11...111
GAIN = -1
5
-25
100
10k
10M
SMALL-SIGNAL FREQUENCY RESPONSE
FREQUENCY (Hz)
GAIN (dB)
-5
0
-10
-15
-20
1k
100k
1M
V
REF
= 100mV
p-p
DAC CODE = 11...111
GAIN = -1
-35
-85
1k
100k
MULTIPLYING FEEDTHROUGH ERROR
-75
FREQUENCY (Hz)
ATTENUATION (dB)
-65
-50
-45
-40
-55
-60
-70
-80
10k
1M
V
REFA
= 20V
p-p
V
REFB
= AGNDB
DAC CODE = 00...00
-94
-106
100
1k
10k
TOTAL HARMONIC DISTORTION + NOISE
vs. FREQUENCY (BANDWIDTH = 80kHz)
-102
FREQUENCY (Hz)
THD (dB)
-100
-98
-96
-104
V
REF
= 6V
RMS
DAC CODE = 111...111
-60
-100
100
10k
100k
TOTAL HARMONIC DISTORTION + NOISE
vs. FREQUENCY (BANDWIDTH > 500kHz)
-75
-65
FREQUENCY (Hz)
THD (dB)
1k
-70
-90
-80
-85
-95
V
REF
= 6V
RMS
DAC CODE = 111...111
PARAMETER
MX78_7J/K/A/B
MIN
MAX
SYMBOL
MX78_7S/T
MIN
MAX
UNITS
Address to
WR SetupTime
t
6
MX7837 only
15
15
ns
Address to
WR Hold Time
t
7
MX7837 only
15
15
ns
LDAC Pulse Width
t
8
MX7837 only
80
80
ns
CONDITIONS
CS to WR Hold Time
0
0
CS to WR Setup Time
t
1
0
ns
t
2
0
ns
WR Pulse Width
t
3
80
80
ns
Data to
WR Setup Time
t
4
80
80
ns
Data to
WR Hold Time
t
5
10
10
ns
TIMING CHARACTERISTICS
(V
DD
= 11.4V to 16.5V, V
SS
= -11.4V to -16.5V, AGNDA = AGNDB = DGND = 0V, T
A
= T
MIN
to T
MAX
, unless otherwise noted.) (Note 5)
Note 5:
All input signals are specified with t
R
= t
F
5ns. Logic swing is 0V to 5V.
MX7837/MX7847
Complete, Dual, 12-Bit
Multiplying DACs
_______________________________________________________________________________________
5
A
AGNDA
A = V
OUTA
, 50mV/div
TIMEBASE = 2
s/div
V
REFA
= 100mV SQUARE WAVE
SMALL-SIGNAL PULSE RESPONSE
A
AGNDA
A = V
OUTA
, 5V/div
TIMEBASE = 2
s/div
V
REFA
= 10V SQUARE WAVE
LARGE-SIGNAL PULSE RESPONSE
______________________________________________________________Pin Description
PIN
MX7837
MX7847
NAME
FUNCTION
1
CS
Chip Select active-low logic input
1
CSA
Chip-Select Input for DAC A active-low logic input
2
R
FBA
Amplifier Feedback Resistor for DAC A
2
CSB
Chip-Select Input for DAC B active-low logic input
3
3
V
REFA
Reference Input Voltage for DAC A
4
4
V
OUTA
Analog Output Voltage from DAC A
5
5
AGNDA
Analog Ground for DAC A
6
6
V
DD
Positive Power Supply
7
7
V
SS
Negative Power Supply
8
8
AGNDB
Analog Ground for DAC B
9
9
V
OUTB
Analog Output Voltage from DAC B
10
10
V
REFB
Reference Input Voltage for DAC B
11
11
DGND
Digital Ground
12
R
FBB
Amplifier Feedback Resistor for DAC B
12
DB11
Data Bit 11 (MSB)
13
13
WR
Write Input active-low logic input (MX7837); positive-edge-triggered input used with
CSA and CSB (MX7847)
14
LDAC
Asynchronous Load DAC input, active-low
14-24
DB10-DB0
Data Bit 10 to Data Bit 0 (LSB)
15
A1
Address Input most significant address input for input latches
16
A0
Address Input least significant address input for input latches
17-20
DB7-DB4
Data Bit 7 to Data Bit 4
21-24
DB3/DB11-
DB0/DB8
Data Bit 3 to Data Bit 0 (LSB), or Data Bit 11 (MSB) to Data Bit 8
____________________________Typical Operating Characteristics (continued)
(T
A
= +25C, V
DD
= 15V, V
SS
= -15V, R
L
= 2k
, C
L
= 100pF, unless otherwise noted.)
PDF 
ZIP