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1
LTC1821
APPLICATIO S
U
DESCRIPTIO
U
FEATURES
TYPICAL APPLICATIO
U
16-Bit, Ultra Precise,
Fast Settling V
OUT
DAC
The LTC
1821 is a parallel input 16-bit multiplying voltage
output DAC that operates from analog supply voltages of
5V up to
15V. INL and DNL are accurate to 1LSB over the
industrial temperature range in both unipolar 0V to 10V and
bipolar
10V modes. Precise 16-bit bipolar
10V outputs are
achieved with on-chip 4-quadrant multiplication resistors.
The LTC1821 is available in a 36-lead SSOP package and is
specified over the industrial temperature range.
The device includes an internal deglitcher circuit that reduces
the glitch impulse to less than 2nVs (typ). The LTC1821
settles to 1LBS in 2
s with a full-scale 10V step. The
combination of fast, precise settling and ultra low glitch make
the LTC1821 ideal for precision industrial control applica-
tions.
The asynchronous CLR pin resets the LTC1821 to zero scale
and resets the LTC1821-1 to midscale.
s
Process Control and Industrial Automation
s
Precision Instrumentation
s
Direct Digital Waveform Generation
s
Software-Controlled Gain Adjustment
s
Automatic Test Equipment
, LTC and LT are registered trademarks of Linear Technology Corporation.
LTC1821/LTC1821-1
Integral Nonlinearity
16-Bit, 4-Quadrant Multiplying DAC with a
Minimum of External Components
DIGITAL INPUT CODE
0
INTEGRAL NONLINEARITY (LSB)
1.0
0.8
0.6
0.4
0.2
0
0.2
0.4
0.6
0.8
1.0
16384
32768
1821 TA02
49152
65535
V
REF
= 10V
V
OUT
=
10V BIPOLAR
V
CC
LTC1821-1
R
FB
I
OUT
R
FB
R
OFS
R
OFS
5V
LD
LD
10
9
3
2
24 23
7
2
6
15pF
17
16
20
13
15
V
V
+
R1
R
COM
8
REF
11
12
14
0.1
F
1
22
V
OUT
15pF
V
OUT
=
1821 TA01
DGND
NC
AGNDS
AGNDF
+
LT
1468
WR
3 TO 6,
25 TO 36
WR
CLR
CLR
16-BIT DAC
R1
R2
16
DATA
INPUTS
0.1
F
15V
15V
0.1
F
+
21
DNC*
19
DNC*
18
*DO NOT CONNECT
DNC*
V
REF
V
REF
V
REF
V
REF
s
2
s Settling to 0.0015% for 10V Step
s
1LSB Max DNL and INL Over Industrial
Temperature Range
s
On-Chip 4-Quadrant Resistors Allow Precise 0V to
10V, 0V to 10V or
10V Outputs
s
Low Glitch Impulse: 2nVs
s
Low Noise: 13nV/
Hz
s
36-Lead SSOP Package
s
Power-On Reset
s
Asynchronous Clear Pin
LTC1821: Reset to Zero Scale
LTC1821-1: Reset to Midscale
2
LTC1821
V
CC
to AGNDF, AGNDS ............................... 0.3V to 7V
V
CC
to DGND .............................................. 0.3V to 7V
Total Supply Voltage (V
+
to V
) ............................... 36V
AGNDF, AGNDS to DGND ............................. V
CC
+ 0.3V
DGND to AGNDF, AGNDS ............................. V
CC
+ 0.3V
REF, R
COM
to AGNDF, AGNDS, DGND ..................
15V
R
OFS
, R
FB
, R1, to AGNDF, AGNDS, DGND ............
15V
Digital Inputs to DGND ............... 0.3V to (V
CC
+ 0.3V)
I
OUT
to AGNDF, AGNDS............... 0.3V to (V
CC
+ 0.3V)
Maximum Junction Temperature .......................... 150
C
Operating Temperature Range
LTC1821C/LTC1821-1C .......................... 0
C to 70
C
LTC1821I/LTC1821-1I ....................... 40
C to 85
C
Storage Temperature Range ................ 65
C to 150
C
Lead Temperature (Soldering, 10 sec)................. 300
C
(Note 1)
ORDER PART
NUMBER
LTC1821ACGW
LTC1821BCGW
LTC1821-1ACGW
LTC1821-1BCGW
LTC1821AIGW
LTC1821BIGW
LTC1821-1AIGW
LTC1821-1BIGW
T
JMAX
= 125
C,
JA
= 80
C/ W
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
TOP VIEW
GW PACKAGE
36-LEAD PLASTIC SSOP WIDE
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
20
19
D4
D5
D6
D7
D8
D9
D10
D11
D12
D13
D14
D15
WR
LD
NC
DNC*
V
DNC*
DGND
V
CC
D3
D2
D1
D0
CLR
REF
R
COM
R1
R
OFS
R
FB
V
OUT
I
OUT
V
+
AGNDS
AGNDF
DNC*
The
q
denotes specifications which apply over the full operating temperature range, otherwise specifications are T
A
= T
MIN
to T
MAX
,
V
+
= 15V, V
= 15V, V
CC
= 5V, V
REF
= 10V, AGNDF = AGNDS = DGND = 0V.
*DO NOT CONNECT
LTC1821B/-1B
LTC1821A/-1A
SYMBOL PARAMETER
CONDITIONS
MIN
TYP
MAX
MIN
TYP
MAX
UNITS
Accuracy
Resolution
q
16
16
Bits
Monotonicity
q
16
16
Bits
INL
Integral Nonlinearity
T
A
= 25
C (Note 2)
2
0.25
1
LSB
T
MIN
to T
MAX
q
2
0.35
1
LSB
DNL
Differential Nonlinearity
T
A
= 25
C
1
0.2
1
LSB
T
MIN
to T
MAX
q
1
0.2
1
LSB
GE
Gain Error
Unipolar Mode
T
A
= 25
C (Note 3)
16
5
16
LSB
T
MIN
to T
MAX
q
24
8
16
LSB
Bipolar Mode
T
A
= 25
C (Note 3)
16
2
16
LSB
T
MIN
to T
MAX
q
24
5
16
LSB
Gain Temperature Coefficient
Gain/
Temperature (Note 4)
q
1
3
1
3
ppm/
C
Unipolar Zero-Scale Error
T
A
= 25
C
3
0.25
2
LSB
T
MIN
to T
MAX
q
6
0.50
4
LSB
Bipolar Zero Error
T
A
= 25
C
12
2
8
LSB
T
MIN
to T
MAX
q
16
3
10
LSB
PSRR
Power Supply Rejection Ratio
V
CC
= 5V
10%
q
2
0.7
2
LSB/V
V
+
, V
=
4.5V to
16.5V
q
2
0.1
2
LSB/V
ABSOLUTE
M
AXI
M
U
M
RATINGS
W
W
W
U
PACKAGE/ORDER I
N
FOR
M
ATIO
N
W
U
U
ELECTRICAL CHARACTERISTICS
Consult factory for parts specified with wider operating temperature ranges.
3
LTC1821
The
q
denotes specifications which apply over the full operating temperature range, otherwise specifications are T
A
= T
MIN
to T
MAX
,
V
+
= 15V, V
= 15V, V
CC
= 5V, V
REF
= 10V, AGNDF = AGNDS = DGND = 0V.
ELECTRICAL CHARACTERISTICS
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Reference Input
R
REF
DAC Input Resistance (Unipolar)
(Note 6)
q
4.5
6
10
k
R1/R2
R1/R2 Resistance (Bipolar)
(Notes 6, 11)
q
9
12
20
k
R
OFS
, R
FB
Feedback and Offset Resistances
(Note 6)
q
9
12
20
k
AC Performance (Note 4)
Output Voltage Settling Time
V
OUT
= 10V (Notes 7, 8)
2
s
Midscale Glitch Impulse
(Note 10)
2
nVs
Digital-Feedthrough
(Note 9)
2
nVs
Multiplying Feedthrough Error
V
REF
=
10V, 10kHz Sine Wave (Note 7)
1
mV
P-P
Multiplying Bandwidth
Code = Full Scale (Note 7)
600
kHz
Output Noise Voltage Density
1kHz to 100kHz (Note 7)
Code = Zero Scale
13
nV/
Hz
Code = Full Scale
20
nV/
Hz
Output Noise Voltage
0.1Hz to 10Hz (Note 7)
Code = Zero Scale
0.45
V
RMS
Code = Full Scale
1
V
RMS
1/f Noise Corner
(Note 7)
30
Hz
Analog Outputs (Note 4)
V
OUT
DAC Output Swing
R
L
= 2k, V
+
= 15V, V
= 15V
q
12.6
V
R
L
= 2k, V
+
= 5V, V
= 5V
q
2.6
V
DAC Output Load Regulation
V
+
= 15V, V
= 15V,
5mA Load
q
0.02
0.2
LSB/mA
I
SC
Short-Circuit Current
V
OUT
= 0V, V
+
= 15V, V
= 15V
q
12
40
mA
SR
Slew Rate
R
L
= 2k, V
+
= 15V, V
= 15V
20
V/
s
R
L
= 2k, V
+
= 5V, V
= 5V
14
V/
s
Digital Inputs
V
IH
Digital Input High Voltage
q
2.4
V
V
IL
Digital Input Low Voltage
q
0.8
V
I
IN
Digital Input Current
q
0.001
1
A
C
IN
Digital Input Capacitance
(Note 4 ) V
IN
= 0V
q
8
pF
Timing Characteristics
t
DS
Data to WR Setup Time
q
60
20
ns
t
DH
Data to WR Hold Time
q
0
12
ns
t
WR
WR Pulse Width
q
60
25
ns
t
LD
LD Pulse Width
q
110
55
ns
t
CLR
Clear Pulse Width
q
60
40
ns
t
LWD
WR to LD Delay Time
q
0
ns
Power Supply
I
CC
Supply Current, V
CC
Digital Inputs = 0V or V
CC
q
1.5
10
A
I
S
Supply Current, V
+
, V
15V
q
4.5
7.0
mA
5V
q
4.0
6.8
mA
V
CC
Supply Voltage
q
4.5
5
5.5
V
V
+
Supply Voltage
q
4.5
16.5
V
V
Supply Voltage
q
16.5
4.5
V
4
LTC1821
Note 8: To 0.0015% for a full-scale change, measured from the rising
edge of LD.
Note 9: REF
= 0V. DAC register contents changed from all 0s to all 1s or all
1s to all 0s. LD low and WR high.
Note 10: Midscale transition code: 0111 1111 1111 1111 to
1000 0000 0000 0000. Unipolar mode, C
FEEDBACK
= 33pF.
Note 11: R1 and R2 are measured between R1 and R
COM
, REF and R
COM
.
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
1LSB =
0.0015% of full scale =
15.3ppm of full scale.
Note 3: Using internal feedback resistor.
Note 4: Guaranteed by design, not subject to test.
Note 5: I
OUT
with DAC register loaded to all 0s.
Note 6: Typical temperature coefficient is 100ppm/
C.
Note 7: Measured in unipolar mode.
ELECTRICAL CHARACTERISTICS
TYPICAL PERFOR A CE CHARACTERISTICS
U
W
TIME (
s)
0
OUTPUT VOLTAGE (mV)
10
0
10
0.6
1.0
1821 G01
20
30
40
0.2
0.4
0.8
20
30
40
C
FEEDBACK
= 30pF
V
REF
= 10V
1nV-s TYPICAL
FREQUENCY (Hz)
90
SIGNAL/(NOISE + DISTORTION) (dB)
70
50
40
10
1k
10k
100k
1821 G03
110
100
60
80
100
V
CC
= 5V
C
FEEDBACK
= 30pF
REFERENCE = 6V
RMS
500kHz FILTER
80kHz FILTER
30kHz FILTER
LD PULSE
5V/DIV
GATED
SETTLING
WAVEFORM
500
V/DIV
500ns/DIV
1821 G02
V
REF
= 10V
C
FEEDBACK
= 20pF
0V TO 10V STEP
FREQUENCY (Hz)
90
SIGNAL/(NOISE + DISTORTION) (dB)
70
50
40
10
1k
10k
100k
1821 G04
110
100
60
80
100
V
CC
= 5V USING AN LT1468
C
FEEDBACK
= 15pF
REFERENCE = 6V
RMS
500kHz FILTER
80kHz FILTER
30kHz
FILTER
FREQUENCY (Hz)
90
SIGNAL/(NOISE + DISTORTION) (dB)
70
50
40
10
1k
10k
100k
1821 G05
110
100
60
80
100
V
CC
= 5V USING AN LT1468
C
FEEDBACK
= 15pF
REFERENCE = 6V
RMS
500kHz FILTER
80kHz FILTER
30kHz FILTER
INTPUT VOLTAGE (V)
0
SUPPLY CURRENT (mA)
3
4
5
4
1821 G06
2
1
0
1
2
3
5
V
CC
= 5V
ALL DIGITAL INPUTS
TIED TOGETHER
Midscale Glitch Impulse
Unipolar Multiplying Mode
Signal-to-(Noise + Distortion)
vs Frequency
Full-Scale Setting Waveform
Bipolar Multiplying Mode
Signal-to-(Noise + Distortion)
vs Frequency, Code = All Zeros
Bipolar Multiplying Mode
Signal-to-(Noise + Distortion)
vs Frequency, Code = All Ones
V
CC
Supply Current vs Digital
Input Voltage
5
LTC1821
TYPICAL PERFOR A CE CHARACTERISTICS
U
W
SUPPLY VOLTAGE (V)
0
0
LOGIC THRESHOLD (V)
0.5
1.0
1.5
2.0
3.0
1
2
3
4
1821 G07
5
7
6
2.5
DIGITAL INPUT CODE
0
1.0
INTEGRAL NONLINEARITY (LSB)
0.8
0.4
0.2
0
1.0
0.4
16384
32768
1821 G08
0.6
0.6
0.8
0.2
49152
65535
DIGITAL INPUT CODE
0
1.0
DIFFERENTIAL NONLINEARITY (LSB) 0.8
0.4
0.2
0
1.0
0.4
16384
32768
1821 G09
0.6
0.6
0.8
0.2
49152
65535
REFERENCE VOLTAGE (V)
10
INTEGRAL NONLINEARITY (LSB)
0.2
0.6
1.0
6
1821 G10
0.2
0.6
0
0.4
0.8
0.4
0.8
1.0
6
2
2
8
8
4
0
4
10
REFERENCE VOLTAGE (V)
10
INTEGRAL NONLINEARITY (LSB)
0.2
0.6
1.0
6
1821 G11
0.2
0.6
0
0.4
0.8
0.4
0.8
1.0
6
2
2
8
8
4
0
4
10
REFERENCE VOLTAGE (V)
10
DIFFERENTIAL NONLINEARITY (LSB)
0.2
0.6
1.0
6
1821 G12
0.2
0.6
0
0.4
0.8
0.4
0.8
1.0
6
2
2
8
8
4
0
4
10
REFERENCE VOLTAGE (V)
10
DIFFERENTIAL NONLINEARITY (LSB)
0.2
0.6
1.0
6
1821 G13
0.2
0.6
0
0.4
0.8
0.4
0.8
1.0
6
2
2
8
8
4
0
4
10
SUPPLY VOLTAGE (V)
1.0
INTEGRAL NONLINEARITY (LSB)
0.8
0.4
0.2
0
1.0
0.4
2
4
5
1821 G14
0.6
0.6
0.8
0.2
3
6
7
V
REF
= 10V
V
REF
= 10V
V
REF
= 2.5V
V
REF
= 2.5V
SUPPLY VOLTAGE (V)
INTEGRAL NONLINEARITY (LSB)
2.0
1.0
0.5
0
2.0
1.0
2
4
5
1821 G15
1.5
1.5
0.5
3
6
7
V
REF
= 10V
V
REF
= 10V
V
REF
= 2.5V
V
REF
= 2.5V
Logic Threshold vs V
CC
Supply
Voltage
Integral Nonlinearity (INL)
Differential Nonlinearity (DNL)
Integral Nonlinearity vs Reference
Voltage in Unipolar Mode
Integral Nonlinearity vs Reference
Voltage in Bipolar Mode
Differential Nonlinearity vs
Reference Voltage in Unipolar Mode
Differential Nonlinearity vs
Reference Voltage in Bipolar Mode
Integral Nonlinearity vs V
CC
Supply
Voltage in Unipolar Mode
Integral Nonlinearity vs V
CC
Supply
Voltage in Bipolar Mode
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