1
DAC7634
DAC7634
16-Bit, Quad Voltage Output
DIGITAL-TO-ANALOG CONVERTER
DAC7634
DESCRIPTION
The DAC7634 is a 16-bit, quad voltage output, digital-
to-analog converter with guaranteed 15-bit monotonic
performance over the specified temperature range. It
accepts 24-bit serial input data, has double-buffered
DAC input logic (allowing simultaneous update of all
DACs), and provides a serial data output for daisy
chaining multiple DACs. Programmable asynchronous
reset clears all registers to a mid-scale code of 8000
H
or
to a zero-scale of 0000
H
. The DAC7634 can operate
from a single +5V supply or from +5V and 5V sup-
plies.
Low power and small size per DAC make the DAC7634
ideal for automatic test equipment, DAC-per-pin pro-
grammers, data acquisition systems, and closed-loop
servo-control. The DAC7634 is available in a 48-lead
SSOP package and offers guaranteed specifications
over the 40
C to +85
C temperature range.
FEATURES
q
LOW POWER: 10mW
q
UNIPOLAR OR BIPOLAR OPERATION
q
SETTLING TIME: 10
s to 0.003%
q
15-BIT LINEARITY AND MONOTONICITY:
40
C to +85
C
q
PROGRAMMABLE RESET TO MID-SCALE
OR ZERO-SCALE
q
DOUBLE-BUFFERED DATA INPUTS
APPLICATIONS
q
PROCESS CONTROL
q
CLOSED-LOOP SERVO-CONTROL
q
MOTOR CONTROL
q
DATA ACQUISITION SYSTEMS
q
DAC-PER-PIN PROGRAMMERS
1999 Burr-Brown Corporation
PDS-1563B
Printed in U.S.A. January, 2000
International Airport Industrial Park Mailing Address: PO Box 11400, Tucson, AZ 85734 Street Address: 6730 S. Tucson Blvd., Tucson, AZ 85706 Tel: (520) 746-1111
Twx: 910-952-1111 Internet: http://www.burr-brown.com/ Cable: BBRCORP Telex: 066-6491 FAX: (520) 889-1510 Immediate Product Info: (800) 548-6132
For most current data sheet and other product
information, visit www.burr-brown.com
DAC A
DAC
Register A
Input
Register A
Shift
Register
DAC B
DAC
Register B
Input
Register B
DAC C
DAC
Register C
Input
Register C
DAC D
DAC
Register D
Input
Register D
V
REF
L AB
V
REF
H AB
V
REF
H
AB Sense
V
REF
L
AB Sense
V
OUT
D
V
OUT
C
V
OUT
B
V
OUT
A
V
OUT
B
Sense
V
REF
L CD V
REF
H CD
SDI
SDO
Control
Logic
CS
CLOCK
RST
RESTSEL
LDAC
LOAD
AGND
DGND
V
OUT
C
Sense
V
OUT
D
Sense
V
OUT
A
Sense
V
CC
V
SS
V
DD
DAC7634
V
REF
L
CD Sense
V
REF
H
CD Sense
SBAS134
2
DAC7634
DAC7634E
DAC7634EB
PARAMETER
CONDITIONS
MIN
TYP
MAX
MIN
TYP
MAX
UNITS
ACCURACY
Linearity Error
3
4
2
3
LSB
Linearity Match
4
2
LSB
Differential Linearity Error
2
3
1
2
LSB
Monotonicity, T
MIN
to T
MAX
14
15
Bits
Bipolar Zero Error
1
2
T
T
mV
Bipolar Zero Error Drift
5
10
T
T
ppm/
C
Full-Scale Error
1
2
T
T
mV
Full-Scale Error Drift
5
10
T
T
ppm/
C
Bipolar Zero Matching
Channel-to-Channel Matching
1
2
1
2
mV
Full Scale Matching
Channel-to-Channel Matching
1
2
1
2
mV
Power Supply Rejection Ratio (PSRR)
At Full Scale
10
100
T
T
ppm/V
ANALOG OUTPUT
Voltage Output
V
REF
= 2.5V, R
L
= 10k
, V
SS
= 5V
V
REF
L
V
REF
H
T
T
V
Output Current
1.25
+1.25
T
T
mA
Maximum Load Capacitance
No Oscillation
500
T
pF
Short-Circuit Current
10, +30
T
mA
Short-Circuit Duration
GND or V
CC
or V
SS
Indefinite
T
REFERENCE INPUT
Ref High Input Voltage Range
V
REF
L + 1.25
+2.5
T
T
V
Ref Low Input Voltage Range
2.5
V
REF
H 1.25
T
T
V
Ref High Input Current
500
T
A
Ref Low Input Current
500
T
A
DYNAMIC PERFORMANCE
Settling Time
To
0.003%, 5V Output Step
8
10
T
T
s
Channel-to-Channel Crosstalk
See Figure 5.
0.5
T
LSB
Digital Feedthrough
2
T
nV-s
Output Noise Voltage
f = 10kHz
60
T
nV/
Hz
DAC Glitch
7FFF
H
to 8000
H
or 8000
H
to 7FFF
H
40
T
nV-s
DIGITAL INPUT
V
IH
0.7 V
DD
T
V
V
IL
0.3 V
DD
T
V
I
IH
10
T
A
I
IL
10
T
A
DIGITAL OUTPUT
V
OH
I
OH
= 0.8mA
3.6
4.5
T
T
V
V
OL
I
OL
= 1.6mA
0.3
0.4
T
T
V
POWER SUPPLY
V
DD
+4.75
+5.0
+5.25
T
T
T
V
V
CC
+4.75
+5.0
+5.25
T
T
T
V
V
SS
5.25
5.0
4.75
T
T
T
V
I
CC
1.5
2
T
T
mA
I
DD
50
T
A
I
SS
2.3
1.5
T
T
mA
Power
15
20
T
T
mW
TEMPERATURE RANGE
Specified Performance
40
+85
T
T
C
T
Specifications same as DAC7634E.
SPECIFICATIONS
At T
A
= T
MIN
to T
MAX
, V
DD
= V
CC
= +5V, V
SS
= 5V, V
REF
H = +2.5V, and V
REF
L = 2.5V, unless otherwise noted.
The information provided herein is believed to be reliable; however, BURR-BROWN assumes no responsibility for inaccuracies or omissions. BURR-BROWN assumes
no responsibility for the use of this information, and all use of such information shall be entirely at the user's own risk. Prices and specifications are subject to change
without notice. No patent rights or licenses to any of the circuits described herein are implied or granted to any third party. BURR-BROWN does not authorize or warrant
any BURR-BROWN product for use in life support devices and/or systems.
3
DAC7634
DAC7634E
DAC7634EB
PARAMETER
CONDITIONS
MIN
TYP
MAX
MIN
TYP
MAX
UNITS
ACCURACY
Linearity Error
(1)
3
4
2
3
LSB
Linearity Match
4
2
LSB
Differential Linearity Error
2
3
1
2
LSB
Monotonicity, T
MIN
to T
MAX
14
15
Bits
Zero Scale Error
1
2
T
T
mV
Zero Scale Error Drift
5
10
T
T
ppm/
C
Full-Scale Error
1
2
T
T
mV
Full-Scale Error Drift
5
10
T
T
ppm/
C
Zero Scale Matching
Channel-to-Channel Matching
1
2
1
2
mV
Full-Scale Matching
Channel-to-Channel Matching
1
2
1
2
mV
Power Supply Rejection Ratio (PSRR)
At Full Scale
10
100
T
T
ppm/V
ANALOG OUTPUT
Voltage Output
V
REF
L = 0V, V
SS
= 0V, R
L
= 10k
0
V
REF
H
T
T
V
Output Current
1.25
+1.25
T
T
mA
Maximum Load Capacitance
No Oscillation
500
T
pF
Short-Circuit Current
30
T
mA
Short-Circuit Duration
GND or V
CC
Indefinite
T
REFERENCE INPUT
Ref High Input Voltage Range
V
REF
L + 1.25
+2.5
T
T
V
Ref Low Input Voltage Range
0
V
REF
H 1.25
T
T
V
Ref High Input Current
250
T
A
Ref Low Input Current
250
T
A
DYNAMIC PERFORMANCE
Settling Time
To
0.003%, 2.5V Output Step
8
10
T
T
s
Channel-to-Channel Crosstalk
See Figure 6.
0.5
T
LSB
Digital Feedthrough
2
T
nV-s
Output Noise Voltage, f = 10kHz
60
T
nV/
Hz
DAC Glitch
7FFF
H
to 8000
H
or 8000
H
to 7FFF
H
40
T
nV-s
DIGITAL INPUT
V
IH
0.7 V
DD
T
V
V
IL
0.3 V
DD
T
V
I
IH
10
T
A
I
IL
10
T
A
DIGITAL OUTPUT
V
OH
I
OH
= 0.8mA
3.6
4.5
T
T
V
V
OL
I
OL
= 1.6mA
0.3
0.4
T
T
V
POWER SUPPLY
V
DD
+4.75
+5.0
+5.25
T
T
T
V
V
CC
+4.75
+5.0
+5.25
T
T
T
V
V
SS
0
0
0
T
T
T
V
I
CC
1.5
2
T
T
mA
I
DD
50
T
A
Power
7.5
10
T
T
mW
TEMPERATURE RANGE
Specified Performance
40
+85
T
T
C
NOTE: (1) If V
SS
= 0V specification applies at Code 0040
H
and above due to possible negative zero-scale error.
T
Specifications same as DAC7634E.
SPECIFICATIONS
At T
A
= T
MIN
to T
MAX
, V
DD
= V
CC
= +5V, V
SS
= 0V, V
REF
H = +2.5V, and V
REF
L = 0V, unless otherwise noted.
4
DAC7634
LINEARITY
DIFFERENTIAL
PACKAGE
SPECIFICATION
ERROR
NONLINEARITY
DRAWING
TEMPERATURE
ORDERING
TRANSPORT
PRODUCT
(LSB)
(LSB)
PACKAGE
NUMBER
RANGE
NUMBER
(1)
MEDIA
DAC7634E
4
3
48-Lead SSOP
333
40
C to +85
C
DAC7634E
Rails
"
"
"
"
"
"
DAC7634E/1K
Tape and Reel
DAC7634EB
3
2
48-Lead SSOP
333
40
C to +85
C
DAC7634EB
Rails
"
"
"
"
"
"
DAC7634EB/1K
Tape and Reel
NOTE: (1) Models with a slash (/) are available only in Tape and Reel in the quantities indicated (e.g., /1K indicates 1000 devices per reel). Ordering 1000 pieces
of "DAC7634E/1K" will get a single 1000-piece Tape and Reel.
PIN DESCRIPTIONS
PIN
NAME
DESCRIPTION
1
NC
No Connection
2
NC
No Connection
3
SDI
Serial Data Input
4
DGND
Digital Ground
5
CLK
Data Clock Input
6
DGND
Digital Ground
7
LDAC
DAC Register Load Control, Rising Edge
Triggered
8
DGND
Digital Ground
9
LOAD
DAC Input Register Load Control, Active Low
10
DGND
Digital Ground
11
CS
Chip Select, Active Low
12
DGND
Digital Ground
13
SDO
Serial Data Output
14
DGND
Digital Ground
15
RSTSEL
Reset Select. Determines the action of RST. If
HIGH, a RST common will set the DAC registers
to mid-scale (8000H). If LOW, a RST command
will set the DAC registers to zero (0000H).
16
DGND
Digital Ground
17
RST
Reset, Rising Edge Triggered. Depending on the
state of RSTSEL, the DAC registers are set to
either mid-scale or zero.
18
DGND
Digital Ground
19
NC
No Connection
20
NC
No Connection
21
DGND
Digital Ground
22
DGND
Digital Ground
23
V
DD
Digital +5V Power Supply
PIN
NAME
DESCRIPTION
24
V
DD
Digital +5V Power Supply
25
V
CC
Analog +5V Power Supply
26
V
CC
Analog +5V Power Supply
27
AGND
Analog Ground
28
AGND
Analog Ground
29
V
SS
Analog 5V Power Supply or 0V Single Supply
30
V
SS
Analog 5V Power Supply or 0V Single Supply
31
V
OUT
D
DAC D Output Voltage
32
V
OUT
D Sense
DAC D's Output Amplifier Inverting Input. Used to
close feedback loop at load.
33
V
REF
L CD Sense
DAC C and D Reference Low Sense Input
34
V
REF
L CD
DAC C and D Reference Low Input
35
V
REF
H CD
DAC C and D Reference High Input
36
V
REF
H CD Sense
DAC C and D Reference High Sense Input
37
V
OUT
C
DAC C Output Voltage
38
V
OUT
C Sense
DAC C's Output Amplifier Inverting Input. Used to
close the feedback loop at the load.
39
V
OUT
B
DAC B Output Voltage
40
V
OUT
B Sense
DAC B's Output Amplifier Inverting Input. Used to
close the feedback loop at the load.
41
V
REF
H AB Sense
DAC A and B Reference High Sense Input
42
V
REF
H AB
DAC A and B Reference High Input
43
V
OUT
L AB
DAC A and B Reference Low Input
44
V
REF
L AB Sense
DAC A and B Reference Low Sense Input
45
V
SS
Analog 5V Power Supply or 0V Single Supply
46
AGND
Analog Ground
47
V
OUT
A
DAC A Output Voltage
48
V
OUT
A Sense
DAC A's Output Amplifier Inverting Input. Used to
close the feedback loop at the load.
ABSOLUTE MAXIMUM RATINGS
(1)
V
CC
and V
DD
to V
SS
.............................................................. 0.3V to 11V
V
CC
and V
DD
to GND ........................................................... 0.3V to 5.5V
V
REF
L
to V
SS
............................................................. 0.3V to (V
CC
V
SS
)
V
CC
to V
REF
H ............................................................ 0.3V to (V
CC
V
SS
)
V
REF
H
to V
REF
L ......................................................... 0.3V to (V
CC
V
SS
)
Digital Input Voltage to GND ................................... 0.3V to V
DD
+ 0.3V
Digital Output Voltage to GND ................................. 0.3V to V
DD
+ 0.3V
Maximum Junction Temperature ................................................... +150
C
Operating Temperature Range ........................................ 40
C to +85
C
Storage Temperature Range ......................................... 65
C to +125
C
Lead Temperature (soldering, 10s) ............................................... +300
C
NOTE: (1) Stresses above those listed under "Absolute Maximum Ratings"
may cause permanent damage to the device. Exposure to absolute maximum
conditions for extended periods may affect device reliability.
ELECTROSTATIC
DISCHARGE SENSITIVITY
This integrated circuit can be damaged by ESD. Burr-Brown
recommends that all integrated circuits be handled with
appropriate precautions. Failure to observe proper handling
and installation procedures can cause damage.
ESD damage can range from subtle performance degradation
to complete device failure. Precision integrated circuits may
be more susceptible to damage because very small parametric
changes could cause the device not to meet its published
specifications.
PACKAGE/ORDERING INFORMATION
5
DAC7634
Top View
SSOP
PIN CONFIGURATION
NC
NC
SDI
DGND
CLK
DGND
LDAC
DGND
LOAD
DGND
CS
DGND
SDO
DGND
RSTSEL
DGND
RST
DGND
NC
NC
DGND
DGND
V
DD
V
DD
V
OUT
A Sense
V
OUT
A
AGND
V
SS
V
REF
L AB Sense
V
REF
L AB
V
REF
H AB
V
REF
H AB Sense
V
OUT
B Sense
V
OUT
B
V
OUT
C Sense
V
OUT
C
V
REF
H CD Sense
V
REF
H CD
V
REF
L CD
V
REF
L CD Sense
V
OUT
D Sense
V
OUT
D
V
SS
V
SS
AGND
AGND
V
CC
V
CC
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
DAC7634
6
DAC7634
TYPICAL PERFORMANCE CURVES: V
SS
= 0V
At T
A
= +25
C, V
DD
= V
CC
= +5V, V
SS
= 0V, V
REFH
= +2.5V, V
REFL
= 0V, representative unit, unless otherwise specified.
+25
C
+85
C
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
LE (LSB)
DLE (LSB)
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR vs CODE
(DAC A, +25
C)
0000
H
2000
H
4000
H
6000
H
8000
H
Digital Input Code
A000
H
C000
H
E000
H
FFFF
H
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
LE (LSB)
DLE (LSB)
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR vs CODE
(DAC B, +25
C)
0000
H
2000
H
4000
H
6000
H
8000
H
Digital Input Code
A000
H
C000
H
E000
H
FFFF
H
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
LE (LSB)
DLE (LSB)
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR vs CODE
(DAC C, +25
C)
0000
H
2000
H
4000
H
6000
H
8000
H
Digital Input Code
A000
H
C000
H
E000
H
FFFF
H
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
LE (LSB)
DLE (LSB)
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR vs CODE
(DAC D, +25
C)
0000
H
2000
H
4000
H
6000
H
8000
H
Digital Input Code
A000
H
C000
H
E000
H
FFFF
H
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
LE (LSB)
DLE (LSB)
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR vs CODE
(DAC A, +85
C)
0000
H
2000
H
4000
H
6000
H
8000
H
Digital Input Code
A000
H
C000
H
E000
H
FFFF
H
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
LE (LSB)
DLE (LSB)
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR vs CODE
(DAC B, +85
C)
0000
H
2000
H
4000
H
6000
H
8000
H
Digital Input Code
A000
H
C000
H
E000
H
FFFF
H
7
DAC7634
TYPICAL PERFORMANCE CURVES: V
SS
= 0V
(Cont.)
At T
A
= +25
C, V
DD
= V
CC
= +5V, V
SS
= 0V, V
REFH
= +2.5V, V
REFL
= 0V, representative unit, unless otherwise specified.
+85
C
(cont.)
40
C
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
LE (LSB)
DLE (LSB)
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR vs CODE
(DAC C, +85
C)
0000
H
2000
H
4000
H
6000
H
8000
H
Digital Input Code
A000
H
C000
H
E000
H
FFFF
H
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
LE (LSB)
DLE (LSB)
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR vs CODE
(DAC D, +85
C)
0000
H
2000
H
4000
H
6000
H
8000
H
Digital Input Code
A000
H
C000
H
E000
H
FFFF
H
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
LE (LSB)
DLE (LSB)
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR vs CODE
(DAC A, 40
C)
0000
H
2000
H
4000
H
6000
H
8000
H
Digital Input Code
A000
H
C000
H
E000
H
FFFF
H
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
LE (LSB)
DLE (LSB)
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR vs CODE
(DAC B, 40
C)
0000
H
2000
H
4000
H
6000
H
8000
H
Digital Input Code
A000
H
C000
H
E000
H
FFFF
H
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
LE (LSB)
DLE (LSB)
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR vs CODE
(DAC C, 40
C)
0000
H
2000
H
4000
H
6000
H
8000
H
Digital Input Code
A000
H
C000
H
E000
H
FFFF
H
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
LE (LSB)
DLE (LSB)
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR vs CODE
(DAC D, 40
C)
0000
H
2000
H
4000
H
6000
H
8000
H
Digital Input Code
A000
H
C000
H
E000
H
FFFF
H
8
DAC7634
TYPICAL PERFORMANCE CURVES: V
SS
= 0V
(Cont.)
At T
A
= +25
C, V
DD
= V
CC
= +5V, V
SS
= 0V, V
REFH
= +2.5V, V
REFL
= 0V, representative unit, unless otherwise specified.
0.30
0.25
0.20
0.15
0.10
0.05
0.00
V
REFH
CURRENT vs CODE
(all DACs sent to indicated code)
V
REF
Current (mA)
0000
H
2000
H
4000
H
6000
H
8000
H
Digital Input Code
A000
H
C000
H
E000
H
FFFF
H
0.00
0.05
0.10
0.15
0.20
0.25
0.30
V
REFL
CURRENT vs CODE
(all DACs sent to indicated code)
V
REF
Current (mA)
0000
H
2000
H
4000
H
6000
H
8000
H
Digital Input Code
A000
H
C000
H
E000
H
FFFF
H
2
1.5
1
0.5
0
Digital Input Code
0000
H
2000
H
4000
H
6000
H
8000
H
A000
H
C000
H
E000H FFFF
H
POSITIVE SUPPLY CURRENT
vs DIGITAL INPUT CODE
I
CC
(mA)
No Load
All DACs
One DAC
2
1.5
1
0.5
0
0.5
1
1.5
2
ZERO-SCALE ERROR vs TEMPERATURE
Zero-Scale Error (mV)
Temperature (
C)
40 30
10
0
20
10
20
40
50
30
70
80
90
60
Code (0040
H
)
DAC C
DAC B
DAC D
DAC A
2
1.5
1
0.5
0
0.5
1
1.5
2
FULL-SCALE ERROR vs TEMPERATURE
Positive Full-Scale Error (mV)
Code (FFFF
H
)
Temperature (
C)
40 30
10
0
20
10
20
40
50
30
70
80
90
60
DAC C
DAC A
DAC B
DAC D
2
1.5
1
0.5
0
POWER SUPPLY CURRENT vs TEMPERATURE
I
CC
(mA)
Temperature (
C)
40 30
10
0
20
10
20
40
50
30
70
80
90
60
Data = FFFF
H
(all DACs)
No Load
9
DAC7634
TYPICAL PERFORMANCE CURVES: V
SS
= 0V
(Cont.)
At T
A
= +25
C, V
DD
= V
CC
= +5V, V
SS
= 0V, V
REFH
= +2.5V, V
REFL
= 0V, representative unit, unless otherwise specified.
BROADBAND NOISE
Time (10
s/div)
Noise Voltage (50
V/div)
BW = 10kHz
Code = 8000
H
+5V
LDAC
0
Time (2
s/div)
OUTPUT VOLTAGE vs SETTLING TIME
(0V to +2.5V)
Output Voltage
Large-Signal Settling Time: 0.5V/div
Small-Signal Settling Time: 4LSB/div
Time (2
s/div)
OUTPUT VOLTAGE vs SETTLING TIME
(+2.5V to 2mV)
Output Voltage
+5V
LDAC
0
Large-Signal Settling Time: 0.5V/div
Small-Signal Settling Time: 4LSB/div
Time (1
s/div)
OUTPUT VOLTAGE
vs MIDSCALE GLITCH PERFORMANCE
Output Voltage (50mV/div)
+5V
LDAC
0
7FFF
H
to 8000
H
Time (1
s/div)
OUTPUT VOLTAGE
vs MIDSCALE GLITCH PERFORMANCE
Output Voltage (50mV/div)
+5V
LDAC
0
8000
H
to 7FFF
H
1000
100
10
Frequency (Hz)
10
100
1000
10000
100000
1000000
OUTPUT NOISE VOLTAGE vs FREQUENCY
Noise (nV/
Hz)
10
DAC7634
TYPICAL PERFORMANCE CURVES: V
SS
= 0V
(Cont.)
At T
A
= +25
C, V
DD
= V
CC
= +5V, V
SS
= 0V, V
REFH
= +2.5V, V
REFL
= 0V, representative unit, unless otherwise specified.
5
4
3
2
1
0
R
LOAD
(k
)
0.001
0.01
0.1
1
10
100
1000
V
OUT
vs R
LOAD
V
OUT
(V)
Source
Sink
11
DAC7634
TYPICAL PERFORMANCE CURVES: V
SS
= 5V
At T
A
= +25
C, V
DD
= V
CC
= +5V, V
SS
= 5V, V
REFH
= +2.5V, V
REFL
= 2.5V, representative unit, unless otherwise specified.
+85
C
+25
C
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
LE (LSB)
DLE (LSB)
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR vs CODE
(DAC A, +25
C)
0000
H
2000
H
4000
H
6000
H
8000
H
Digital Input Code
A000
H
C000
H
E000
H
FFFF
H
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
LE (LSB)
DLE (LSB)
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR vs CODE
(DAC B, +25
C)
0000
H
2000
H
4000
H
6000
H
8000
H
Digital Input Code
A000
H
C000
H
E000
H
FFFF
H
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
LE (LSB)
DLE (LSB)
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR vs CODE
(DAC C, +25
C)
0000
H
2000
H
4000
H
6000
H
8000
H
Digital Input Code
A000
H
C000
H
E000
H
FFFF
H
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
LE (LSB)
DLE (LSB)
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR vs CODE
(DAC D, +25
C)
0000
H
2000
H
4000
H
6000
H
8000
H
Digital Input Code
A000
H
C000
H
E000
H
FFFF
H
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
LE (LSB)
DLE (LSB)
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR vs CODE
(DAC A, +85
C)
0000
H
2000
H
4000
H
6000
H
8000
H
Digital Input Code
A000
H
C000
H
E000
H
FFFF
H
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
LE (LSB)
DLE (LSB)
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR vs CODE
(DAC B, +85
C)
0000
H
2000
H
4000
H
6000
H
8000
H
Digital Input Code
A000
H
C000
H
E000
H
FFFF
H
12
DAC7634
TYPICAL PERFORMANCE CURVES: V
SS
= 5V
(Cont.)
At T
A
= +25
C, V
DD
= V
CC
= +5V, V
SS
= 5V, V
REFH
= +2.5V, V
REFL
= 2.5V, representative unit, unless otherwise specified.
40
C
+85
C
(cont.)
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
LE (LSB)
DLE (LSB)
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR vs CODE
(DAC C, +85
C)
0000
H
2000
H
4000
H
6000
H
8000
H
Digital Input Code
A000
H
C000
H
E000
H
FFFF
H
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
LE (LSB)
DLE (LSB)
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR vs CODE
(DAC A, 40
C)
0000
H
2000
H
4000
H
6000
H
8000
H
Digital Input Code
A000
H
C000
H
E000
H
FFFF
H
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
LE (LSB)
DLE (LSB)
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR vs CODE
(DAC B, 40
C)
0000
H
2000
H
4000
H
6000
H
8000
H
Digital Input Code
A000
H
C000
H
E000
H
FFFF
H
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
LE (LSB)
DLE (LSB)
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR vs CODE
(DAC C, 40
C)
0000
H
2000
H
4000
H
6000
H
8000
H
Digital Input Code
A000
H
C000
H
E000
H
FFFF
H
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
LE (LSB)
DLE (LSB)
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR vs CODE
(DAC D, 40
C)
0000
H
2000
H
4000
H
6000
H
8000
H
Digital Input Code
A000
H
C000
H
E000
H
FFFF
H
1.0
0.5
0
0.5
1.0
1.5
2.0
2.5
3.0
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
LE (LSB)
DLE (LSB)
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR vs CODE
(DAC D, +85
C)
0000
H
2000
H
4000
H
6000
H
8000
H
Digital Input Code
A000
H
C000
H
E000
H
FFFF
H
13
DAC7634
TYPICAL PERFORMANCE CURVES: V
SS
= 5V
(Cont.)
At T
A
= +25
C, V
DD
= V
CC
= +5V, V
SS
= 5V, V
REFH
= +2.5V, V
REFL
= 2.5V, representative unit, unless otherwise specified.
+0.6
+0.5
+0.4
+0.3
+0.2
+0.1
0.0
V
REFH
CURRENT vs CODE
(all DACs sent to indicated code)
V
REF
Current (mA)
0000
H
2000
H
4000
H
6000
H
8000
H
Digital Input Code
A000
H
C000
H
E000
H
FFFF
H
0.0
0.1
0.2
0.3
0.4
0.5
0.6
V
REFL
CURRENT vs CODE
(all DACs sent to indicated code)
V
REF
Current (mA)
0000
H
2000
H
4000
H
6000
H
8000
H
Digital Input Code
A000
H
C000
H
E000
H
FFFF
H
2
1.5
1
0.5
0
0.5
1
1.5
2
ZERO-SCALE ERROR vs TEMPERATURE
(Code 8000
H
)
Zero-Scale Error (mV)
Temperature (
C)
40 30
10
0
20
10
20
40
50
30
70
80
90
60
DAC A
DAC B
DAC D
DAC C
2
1.5
1
0.5
0
0.5
1
1.5
2
POSITIVE FULL-SCALE ERROR vs TEMPERATURE
(Code FFFF
H
)
Positive Full-Scale Error (mV)
Temperature (
C)
40 30
10
0
20
10
20
40
50
30
70
80
90
60
DAC B
DAC A
DAC D
DAC C
2
1.5
1
0.5
0
0.5
1
1.5
2
NEGATIVE FULL-SCALE ERROR vs TEMPERATURE
(Code 0000
H
)
Negative Full-Scale Error (mV)
Temperature (
C)
40 30
10
0
20
10
20
40
50
30
70
80
90
60
DAC D
DAC A
DAC B
DAC C
3
2
1
0
1
2
3
POWER SUPPLY CURRENT vs TEMPERATURE
I
Q
(mA)
I
CC
I
SS
Temperature (
C)
40 30
10
0
20
10
20
40
50
30
70
80
90
60
Data = FFFF
H
(all DACs)
No Load
14
DAC7634
TYPICAL PERFORMANCE CURVES: V
SS
= 5V
(Cont.)
At T
A
= +25
C, V
DD
= V
CC
= +5V, V
SS
= 5V, V
REFH
= +2.5V, V
REFL
= 2.5V, representative unit, unless otherwise specified.
5
4
3
2
1
0
1
2
3
4
5
R
LOAD
(k
)
0.001
0.01
1
0.1
100
10
1000
V
OUT
vs R
LOAD
V
OUT
(V)
Source
Sink
Time (2
s/div)
OUTPUT VOLTAGE vs SETTLING TIME
(2.5V to +2.5V)
Output Voltage
+5V
LDAC
0
Large-Signal Settling Time: 1V/div
Small-Signal Settling Time: 2LSB/div
Time (2
s/div)
OUTPUT VOLTAGE vs SETTLING TIME
(+2.5V to 2.5V)
Output Voltage
Large-Signal Settling Time: 1V/div
Small-Signal Settling Time:
2LSB/div
+5V
LDAC
0
2
1.5
1
0.5
0
POSITIVE SUPPLY CURRENT
vs DIGITAL INPUT CODE
I
CC
(mA)
Digital Input Code
0000
H
2000
H
4000
H
6000
H
8000
H
A000
H
C000
H
E000
H
FFFF
H
No Load
All DACs
One DAC
15
DAC7634
THEORY OF OPERATION
The DAC7634 is a quad voltage output, 16-bit Digital-to-
Analog Converter (DAC). The architecture is an R-2R
ladder configuration with the three MSB's segmented, fol-
lowed by an operational amplifier that serves as a buffer.
Each DAC has its own R-2R ladder network, segmented
MSBs, and output op amp, as shown in Figure 1. The
minimum voltage output (zero-scale) and maximum voltage
output (full-scale) are set by the external voltage references
(V
REF
L and V
REF
H, respectively).
The digital input is a 24-bit serial word that contains a 2-bit
address code for selecting one of four DACs, a quick load
bit, five unused bits, and the 16-bit DAC code (MSB first).
The converters can be powered from either a single +5V
supply or a dual
5V supply. The device offers a reset
function which immediately sets all DAC output voltages
and DAC registers to mid-scale code 8000
H
or to zero-scale,
code 0000
H
. See Figures 2 and 3 for the basic operation of
the DAC7634.
FIGURE 1. DAC7634 Architecture.
FIGURE 2. Basic Single-Supply Operation of the DAC7634.
R
2R
2R
2R
2R
2R
2R
2R
2R
2R
V
REF
H
V
OUT
V
OUT
Sense
V
REF
H Sense
V
REF
L
V
REF
L Sense
R
F
NC
NC
SDI
DGND
CLK
DGND
LDAC
DGND
LOAD
DGND
CS
DGND
SDO
DGND
RSTSEL
DGND
RST
DGND
NC
NC
DGND
DGND
V
DD
V
DD
V
OUT
A Sense
V
OUT
A
AGND
V
SS
V
REF
L AB Sense
V
REF
L AB
V
REF
H AB
V
REF
H AB Sense
V
OUT
B Sense
V
OUT
B
V
OUT
C Sense
V
OUT
C
V
REF
H CD Sense
V
REF
H CD
V
REF
L CD
V
REF
L CD Sense
V
OUT
D Sense
V
OUT
D
V
SS
V
SS
AGND
AGND
V
CC
V
CC
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
DAC7634
Reset DAC Registers
Chips Select
Serial Data Out
Serial Data In
Clock
Load DAC Registers
Load
NC = No Connection
0V to +2.5V
0V to +2.5V
0V to +2.5V
0V to +2.5V
+2.5000V
+2.5000V
+5V
0.1
F
1
F
+
16
DAC7634
FIGURE 3. Basic Dual-Supply Operation of the DAC7634.
ANALOG OUTPUTS
When V
SS
= 5V (dual supply operation), the output ampli-
fier can swing to within 2.25V of the supply rails, guaran-
teed over the 40
C to +85
C temperature range. When
V
SS
= 0V (single-supply operation), and with R
LOAD
also
connected to ground, the output can swing to ground. Care
must also be taken when measuring the zero-scale error
when V
SS
= 0V. Since the output voltage cannot swing
below ground, the output voltage may not change for the
first few digital input codes (0000
H
, 0001
H
, 0002
H
, etc.) if
the output amplifier has a negative offset. At the negative
limit of 2mV, the first specified output starts at code 0040
H
.
Due to the high accuracy of these D/A converters, system
design problems such as grounding and contact resistance
become very important. A 16-bit converter with a 2.5V full-
scale range has a 1LSB value of 38
V. With a load current
of 1mA, series wiring and connector resistance of only
40m
(R
W2
) will cause a voltage drop of 40
V, as shown in
Figure 4. To understand what this means in terms of a
system layout, the resistivity of a typical 1 ounce copper-
clad printed circuit board is 1/2 m
per square. For a 1mA
load, a 10 milli-inch wide printed circuit conductor 600
milli-inches long will result in a voltage drop of 30
V.
The DAC7634 offers a force and sense output configuration
for the high open-loop gain output amplifier. This feature
allows the loop around the output amplifier to be closed at
the load (as shown in Figure 4), thus ensuring an accurate
output voltage.
V
OUT
A Sense
V
OUT
A
AGND
V
SS
V
REF
L AB Sense
V
REF
L AB
V
REF
H AB
V
REF
H AB Sense
V
OUT
B Sense
V
OUT
B
48
47
46
45
44
43
42
41
40
39
DAC7634
R
W1
R
W2
+2.5V
+V
V
OUT
R
W1
R
W2
V
OUT
FIGURE 4. Analog Output Closed-Loop Configuration
(1/2 DAC7634). R
W
represents wiring resis-
tances.
NC
NC
SDI
DGND
CLK
DGND
LDAC
DGND
LOAD
DGND
CS
DGND
SDO
DGND
RSTSEL
DGND
RST
DGND
NC
NC
DGND
DGND
V
DD
V
DD
V
OUT
A Sense
V
OUT
A
AGND
V
SS
V
REF
L AB Sense
V
REF
L AB
V
REF
H AB
V
REF
H AB Sense
V
OUT
B Sense
V
OUT
B
V
OUT
C Sense
V
OUT
C
V
REF
H CD Sense
V
REF
H CD
V
REF
L CD
V
REF
L CD Sense
V
OUT
D Sense
V
OUT
D
V
SS
V
SS
AGND
AGND
V
CC
V
CC
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
DAC7634
Reset DAC Registers
Chips Select
Serial Data Out
Serial Data In
Clock
Load DAC Registers
Load
NC = No Connection
2.5V to +2.5V
2.5V to +2.5V
2.5V to +2.5V
2.5V to +2.5V
+2.5000V
+2.5000V
2.5000V
2.5000V
+5V
+5V
0.1
F
1
F
1
F
+
0.1
F
0.1
F
1
F
5V
5V
+5V
+
+
17
DAC7634
REFERENCE INPUTS
The reference inputs, V
REF
L and V
REF
H, can be any voltage
between V
SS
+ 2.5V and V
CC
2.5V, provided that V
REF
H
is at least 1.25V greater than V
REF
L. The minimum output of
each DAC is equal to V
REF
L
plus a small offset voltage
(essentially, the offset of the output op amp). The maximum
output is equal to V
REF
H plus a similar offset voltage. Note
that V
SS
(the negative power supply) must either be
connected to ground or must be in the range of 4.75V to
5.25V. The voltage on V
SS
sets several bias points within
the converter. If V
SS
is not in one of these two configura-
tions, the bias values may be in error and proper operation
of the device is not guaranteed.
The current into the V
REF
H input and out of V
REF
L depends
on the DAC output voltages, and can vary from a few
microamps to approximately 0.5mA. The reference input
appears as a varying load to the reference. If the reference
can sink or source the required current, a reference buffer is
not required. The DAC7634 features a reference drive and
sense connection such that the internal errors caused by the
changing reference current and the circuit impedances can
be minimized. Figures 5 through 13 show different reference
configurations, and the effect on the linearity and differen-
tial linearity.
+2.5V
+V
2.5V
V
V
OUT
5V
V
OUT
V
OUT
A Sense
V
OUT
A
AGND
V
SS
V
REF
L AB Sense
V
REF
L AB
V
REF
H AB
V
REF
H AB Sense
V
OUT
B Sense
V
OUT
B
48
47
46
45
44
43
42
41
40
39
DAC7634
2200pF
100
1000pF
1000pF
2200pF
+V
OPA2234
V
100
FIGURE 5. Dual Supply Configuration-Buffered References, used for Dual Supply Performance
FIGURE 6. Single-Supply Buffered Reference with a Reference Low of 50mV (1/2 DAC7634).
V
OUT
V
OUT
A Sense
V
OUT
A
AGND
V
SS
V
REF
L AB Sense
V
REF
L AB
V
REF
H AB
V
REF
H AB Sense
V
OUT
B Sense
V
OUT
B
48
47
46
45
44
43
42
41
40
39
DAC7634
+2.5V
+V
OPA2350
98k
+0.050V
2k
V
OUT
NOTE: V
REF
L has been chosen to be 50mV to allow for current sinking voltage
drops across the 100
resistor and the output stage of the buffer op amp.
2200pF
100
1000pF
1000pF
2200pF
+V
100
18
DAC7634
FIGURE 9. Single-Supply Buffered Reference with V
REF
L = +1.25V and V
REF
H = +2.5V (1/2 DAC7634).
FIGURE 7. Integral Linearity and Differential Linearity
Error Curves for Figure 6.
FIGURE 8. Integral Linearity and Differential Linearity
Error Curves for Figure 9.
FIGURE 10. Single-Supply Buffered V
REF
H (1/2 DAC7634).
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
LE (LSB)
DLE (LSB)
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR vs CODE
(DAC A, +25
C)
0000
H
2000
H
4000
H
6000
H
8000
H
Digital Input Code
A000
H
C000
H
E000
H
FFFF
H
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
LE (LSB)
DLE (LSB)
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR vs CODE
(DAC A, +25
C)
0000
H
2000
H
4000
H
6000
H
8000
H
Digital Input Code
A000
H
C000
H
E000
H
FFFF
H
+2.5V
+V
+1.25V
+V
V
OUT
V
OUT
A Sense
V
OUT
A
AGND
V
SS
V
REF
L AB Sense
V
REF
L AB
V
REF
H AB
V
REF
H AB Sense
V
OUT
B Sense
V
OUT
B
48
47
46
45
44
43
42
41
40
39
DAC7634
OPA2350
V
OUT
2200pF
100
1000pF
1000pF
2200pF
+V
100
+V
1000pF
2200pF
100
+2.5V
OPA2350
+V
V
OUT
V
OUT
A Sense
V
OUT
A
AGND
V
SS
V
REF
L AB Sense
V
REF
L AB
V
REF
H AB
V
REF
H AB Sense
V
OUT
B Sense
V
OUT
B
48
47
46
45
44
43
42
41
40
39
DAC7634
V
OUT
19
DAC7634
FIGURE 11. Linearity and Differential Linearity Error Curves
for Figure 10.
FIGURE 12. Low Cost Single-Supply Configuration.
FIGURE 13. Linearity and Differential Linearity Error Curves
for Figure 12.
INPUT
DAC
A1
A0
CS
RST
RSTSEL
LDAC
LOAD
REGISTER
REGISTER
MODE
DAC
L
L
L
H
X
X
L
Write
Hold
Write Input
A
L
H
L
H
X
X
L
Write
Hold
Write Input
B
H
L
L
H
X
X
L
Write
Hold
Write Input
C
H
H
L
H
X
X
L
Write
Hold
Write Input
D
X
X
H
H
X
H
Hold
Write
Update
All
X
X
H
H
X
H
H
Hold
Hold
Hold
All
X
X
X
L
X
X
Reset to Zero
Reset to Zero
Reset to Zero
All
X
X
X
H
X
X
Reset to Midscale
Reset to Midscale
Reset to Midscale
All
TABLE I. DAC7634 Logic Truth Table.
2.5
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
LE (LSB)
DLE (LSB)
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR vs CODE
(DAC A, +25
C)
0000
H
2000
H
4000
H
6000
H
8000
H
Digital Input Code
A000
H
C000
H
E000
H
FFFF
H
+2.5V
+V
V
OUT
V
OUT
A Sense
V
OUT
A
AGND
V
SS
V
REF
L AB Sense
V
REF
L AB
V
REF
H AB
V
REF
H AB Sense
V
OUT
B Sense
V
OUT
B
48
47
46
45
44
43
42
41
40
39
DAC7634
V
OUT
2.5
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
2.5
2.0
1.5
1.0
0.5
0
0.5
1.0
1.5
2.0
LE (LSB)
DLE (LSB)
LINEARITY ERROR AND
DIFFERENTIAL LINEARITY ERROR vs CODE
(DAC A, +25
C)
0000
H
2000
H
4000
H
6000
H
8000
H
Digital Input Code
A000
H
C000
H
E000
H
FFFF
H
DIGITAL INTERFACE
Table I shows the basic control logic for the DAC7634. The
interface consists of a Signal Data Clock (CLK) input, Serial
Data (SDI), DAC Input Register Load Control Signal
(LOAD), and DAC Register Load Control Signal (LDAC).
In addition, a Chip Select (CS) input is available to enable
serial communication when there are multiple serial devices.
An asynchronous Reset (RST) input, by the rising edge, is
provided to simplify start-up conditions, periodic resets, or
emergency resets to a known state, depending on the status
of the reset select (RSTSEL) signal.
The DAC code, quick load control, and address are provided
via a 24-bit serial interface (see Figure 15). The first two bits
select the input register that will be updated when LOAD
goes LOW. The third bit is a "Quick Load" bit such that if
HIGH, the code in the shift register is loaded into ALL
DAC's input register when LOAD signal goes LOW. If the
"Quick Load" bit is LOW, the content of shift register is
loaded only to the DAC input register that is addressed. The
"Quick Load" bit is followed by five unused bits. The last
sixteen bits (MSB first) are the DAC code.
B23
B22
B21
B20
B19
B18
B17
B16
B15
B14
B13
B12
B11
B10
B9
B8
B7
B6
B5
B4
B3
B2
B1
B0
A1
A0
X
X
X
X
X
D15
D14
D13
D12
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
QUICK
LOAD
SERIAL DATA INPUT
20
DAC7634
(1)
V
V
L
V
H
V
L
N
OUT
REF
REF
REF
=
+
(
)
,
65 536
DAC7634
CLK
SDI
CS
SCK
DIN
CS
SDO
DAC7634
CLK
SDI
CS
SDO
DAC7634
CLK
SDI
CS
SDO
To
Other
Serial
Devices
FIGURE 14. Daisy-Chaining DAC7634.
The internal DAC register is edge triggered and not level
triggered. When the LDAC signal is transitioned from LOW
to HIGH, the digital word currently in the DAC input
register is latched. The first set of registers (the DAC input
registers) are level triggered via the LOAD signal. This
double-buffered architecture has been designed so that new
data can be entered for each DAC without disturbing the
analog outputs. When the new data has been entered into the
device, all of the DAC outputs can be updated simulta-
neously by the rising edge of LDAC. Additionally, it allows
the DAC input registers to be written to at any point, then the
DAC output voltages can be synchronously changed via a
trigger signal (LDAC).
Note that CS and CLK are combined with an OR gate, which
controls the serial-to-parallel shift register. These two inputs
are completely interchangeable. In addition, care must be
taken with the state of CLK when CS rises at the end of a
serial transfer. If CLK is LOW when CS rises, the OR gate
will provide a rising edge to the shift register, shifting the
internal data one additional bit. The result will be incorrect
data and possible selection of the wrong input register(s). If
both CS and CLK are used, CS should rise only when CLK
is HIGH. If not, then either CS or CLK can be used to
operate the shift register. See Table II for more information.
SERIAL-DATA OUTPUT
The Serial-Data Output (SDO) is the internal shift register's
output. For DAC7634, the SDO is a driven output and does
not require an external pull-up. Any number of DAC7634's
can be daisy chained by connecting the SDO pin of one
device to the SDI pin of the following device in the chain,
as shown in Figure 14.
DIGITAL TIMING
Figure 15 and Table III provide detailed timing for the
digital interface of the DAC7634.
DIGITAL INPUT CODING
The DAC7634 input data is in Straight Binary format. The
output voltage is given by Equation 1.
where N is the digital input code. This equation does not
CS
(1)
CLK
(1)
LOAD
RST
SERIAL SHIFT REGISTER
H
(2)
X
(3)
H
H
No Change
L
(4)
L
H
H
No Change
L
(5)
H
H
Advanced One Bit
L
H
H
Advanced One Bit
H
(6)
X
L
(7)
H
No Change
H
(6)
X
H
(8)
No Change
NOTES: (1) CS and CLK are interchangeable. (2) H = Logic HIGH.
(3) X = Don't Care. (4) L = Logic LOW (5) = Positive Logic Transition.
(6) A HIGH value is suggested in order to avoid a "false clock" from advancing
the shift register and changing the shift register. (7) If data is clocked into the
serial register while LOAD is LOW, the selected DAC register will change as
the shift register bits "flow" through A1 and A0. This will corrupt the data in
each DAC register that has been erroneously selected. (8) Rising edge of RST
causes no change in the contents of the serial shift register.
TABLE II. Serial Shift Register Truth Table.
include the effects of offset (zero-scale) or gain (full-scale)
errors.
DIGITALLY-PROGRAMMABLE
CURRENT SOURCE
The DAC7634 offers a unique set of features that allows a
wide range of flexibility in designing applications circuits
such as programmable current sources. The DAC7634 offers
both a differential reference input, as well as an open-loop
configuration around the output amplifier. The open-loop
configuration around the output amplifier allows a transistor
to be placed within the loop to implement a digitally-
programmable, unidirectional current source. The availabil-
ity of a differential reference allows programmability for
both the full-scale and zero-scale currents. The output cur-
rent is calculated as:
(2)
I
V
H
V
L
R
V
L R
OUT
REF
REF
SENSE
REF
SENSE
=
+
(
)
,
/
N
65 536
21
DAC7634
SYMBOL
DESCRIPTION
MIN
UNITS
t
DS
Data Valid to CLK Rising
10
ns
t
DH
Data Held Valid after CLK Rises
20
ns
t
CH
CLK HIGH
25
ns
t
CL
CLK LOW
25
ns
t
CSS
CS LOW to CLK Rising
15
ns
t
CSH
CLK HIGH to CS Rising
0
ns
t
LD1
LOAD HIGH to CLK Rising
10
ns
t
LD2
CLK Rising to LOAD LOW
30
ns
t
LDRW
LOAD LOW Time
30
ns
t
LDDL
LDAC LOW Time
100
ns
t
LDDH
LDAC HIGH Time
150
ns
t
RSSS
RESETSEL Valid to RESET HIGH
0
ns
t
RSSH
RESET HIGH to RESETSEL Not Valid
100
ns
t
RSTL
RESET LOW Time
10
ns
t
RSTH
RESET HIGH Time
10
ns
t
S
Settling Time
10
s
TABLE III. Timing Specifications (T
A
= 40
C to +85
C).
FIGURE 15. Digital Input and Output Timing.
A1
(LSB)
SDI
CLK
CS
LOAD
A0
D15
D1
D0
SDI
CLK
LDAC
RESET
V
OUT
tcss
t
LD1
t
CL
t
CH
t
DS
t
DH
t
LD2
t
LDRW
t
S
t
RSTH
t
RSTL
t
RSSS
t
RSSH
t
CSH
t
S
1 LSB
ERROR BAND
1 LSB
ERROR BAND
RESETSEL
X
X
X
X
X
QUICK
LOAD
(MSB)
t
LDDD
LDAC
t
LDDH
t
LDDL
22
DAC7634
(3)
FIGURE 16. 4-to-20mA Digitally Controlled Current Source (1/2 DAC7634).
I
OUT
V
PROGRAMMED
125
I
OUT
V
PROGRAMMED
125
GND
V
OUT
A Sense
V
OUT
A
AGND
V
SS
V
REF
L AB Sense
V
REF
L AB
V
REF
H AB
V
REF
H AB Sense
V
OUT
B Sense
V
OUT
B
48
47
46
45
44
43
42
41
40
39
DAC7634
+2.5V
OPA2350
80k
20k
2200pF
100
1000pF
1000pF
2200pF
+V
+V
100
Figure 16 shows a DAC7634 in a 4mA to 20mA current
output configuration. The output current can be determined
by Equation 3:
At full-scale, the output current is 16mA, plus the 4mA, for
the zero current. At zero scale the output current is the offset
current of 4mA (0.5V/125
).
I
V
V
N
V
OUT
=
+
2 5
0 5
125
65 536
0 5
125
.
.
,
.
PACKAGING INFORMATION
ORDERABLE DEVICE
STATUS(1)
PACKAGE TYPE
PACKAGE DRAWING
PINS
PACKAGE QTY
DAC7634E
ACTIVE
SSOP
DL
48
30
DAC7634E/1K
ACTIVE
SSOP
DL
48
1000
DAC7634EB
ACTIVE
SSOP
DL
48
30
DAC7634EB/1K
ACTIVE
SSOP
DL
48
1000
(1) The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in
a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
PACKAGE OPTION ADDENDUM
www.ti.com
3-Oct-2003
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