LTC1821
16-Bit, Ultra Precise,
Fast Settling V
OUT
DAC
FEATURES
s
s
DESCRIPTIO
s
s
s
s
s
s
2µs Settling to 0.0015% for 10V Step
1LSB Max DNL and INL Over Industrial
Temperature Range
On-Chip 4-Quadrant Resistors Allow Precise 0V to
10V, 0V to –10V or
±10V
Outputs
Low Glitch Impulse: 2nV•s
Low Noise: 13nV/√Hz
36-Lead SSOP Package
Power-On Reset
Asynchronous Clear Pin
LTC1821: Reset to Zero Scale
LTC1821-1: Reset to Midscale
APPLICATIO S
s
s
s
s
s
Process Control and Industrial Automation
Precision Instrumentation
Direct Digital Waveform Generation
Software-Controlled Gain Adjustment
Automatic Test Equipment
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 2nV•s (typ). The LTC1821
settles to 1LBS in 2µs 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.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
V
REF
–V
REF
16-Bit, 4-Quadrant Multiplying DAC with a
Minimum of External Components
LTC1821/LTC1821-1
Integral Nonlinearity
1.0
0.8
INTEGRAL NONLINEARITY (LSB)
10
R1
R1
16
DATA
INPUTS
3 TO 6,
25 TO 36
9
R
COM
R2
LTC1821-1
16-BIT DAC
WR LD CLR
WR
LD
CLR
24 23
7
DNC* DNC* DNC* NC
18
19
21
22
DGND
1
AGNDF AGNDS
17
16
1821 TA01
*DO NOT CONNECT
+
–
–
2
+
3
5V
6
0.1µF
LT
®
1468
15pF
15pF
8
2
V
CC
11
R
OFS
R
OFS
R
FB
13
V
OUT
V
–
12
R
FB
14
I
OUT
V
+
15
15V
0.1µF
V
REF
V
OUT
=
–V
REF
–15V
0.1µF
REF
20
U
V
REF
= 10V
V
OUT
=
±10V
BIPOLAR
0.6
0.4
0.2
0
–0.2
–0.4
–0.6
–0.8
–1.0
0
49152
32768
16384
DIGITAL INPUT CODE
65535
1821 TA02
U
U
1
LTC1821
ABSOLUTE
MAXIMUM
RATINGS
(Note 1)
PACKAGE/ORDER INFORMATION
TOP VIEW
DGND
V
CC
D3
D2
D1
D0
CLR
REF
R
COM
1
2
3
4
5
6
7
8
9
36 D4
35 D5
34 D6
33 D7
32 D8
31 D9
30 D10
29 D11
28 D12
27 D13
26 D14
25 D15
24 WR
23 LD
22 NC
21 DNC*
20 V
–
19 DNC*
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
ORDER PART
NUMBER
LTC1821ACGW
LTC1821BCGW
LTC1821-1ACGW
LTC1821-1BCGW
LTC1821AIGW
LTC1821BIGW
LTC1821-1AIGW
LTC1821-1BIGW
R1 10
R
OFS
11
R
FB
12
V
OUT
13
I
OUT
14
V
+
15
AGNDS 16
AGNDF 17
DNC* 18
GW PACKAGE
36-LEAD PLASTIC SSOP WIDE
T
JMAX
= 125°C,
θ
JA
= 80°C/ W
*DO NOT CONNECT
Consult factory for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
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.
SYMBOL PARAMETER
Accuracy
Resolution
Monotonicity
INL
DNL
GE
Integral Nonlinearity
Differential Nonlinearity
Gain Error
T
A
= 25°C (Note 2)
T
MIN
to T
MAX
T
A
= 25°C
T
MIN
to T
MAX
Unipolar Mode
T
A
= 25°C (Note 3)
T
MIN
to T
MAX
Bipolar Mode
T
A
= 25°C (Note 3)
T
MIN
to T
MAX
Gain Temperature Coefficient
Unipolar Zero-Scale Error
Bipolar Zero Error
PSRR
Power Supply Rejection Ratio
∆Gain/∆Temperature
(Note 4)
T
A
= 25°C
T
MIN
to T
MAX
T
A
= 25°C
T
MIN
to T
MAX
V
CC
= 5V
±10%
V
+
, V
–
=
±4.5V
to
±16.5V
q
q
q
q
CONDITIONS
LTC1821B/-1B
MIN
TYP
MAX
16
16
±2
±2
±1
±1
±16
±24
±
16
±
24
1
3
±3
±6
±12
±16
2
±2
LTC1821A/-1A
MIN
TYP MAX
16
16
±0.25
±0.35
±0.2
±0.2
±5
±8
±2
±5
1
±0.25
±0.50
±2
±3
0.7
±0.1
±1
±1
±1
±1
±16
±16
±16
±16
3
±2
±4
±8
±10
2
±2
UNITS
Bits
Bits
LSB
LSB
LSB
LSB
LSB
LSB
LSB
LSB
ppm/°C
LSB
LSB
LSB
LSB
LSB/V
LSB/V
q
q
q
q
q
q
q
2
U
W
U
U
W W
W
LTC1821
ELECTRICAL CHARACTERISTICS
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.
SYMBOL
R
REF
R1/R2
R
OFS
, R
FB
PARAMETER
DAC Input Resistance (Unipolar)
R1/R2 Resistance (Bipolar)
Feedback and Offset Resistances
Output Voltage Settling Time
Midscale Glitch Impulse
Digital-Feedthrough
Multiplying Feedthrough Error
Multiplying Bandwidth
Output Noise Voltage Density
CONDITIONS
(Note 6)
(Notes 6, 11)
(Note 6)
∆V
OUT
= 10V (Notes 7, 8)
(Note 10)
(Note 9)
V
REF
=
±10V,
10kHz Sine Wave (Note 7)
Code = Full Scale (Note 7)
1kHz to 100kHz (Note 7)
Code = Zero Scale
Code = Full Scale
0.1Hz to 10Hz (Note 7)
Code = Zero Scale
Code = Full Scale
(Note 7)
R
L
= 2k, V
+
= 15V, V
–
= –15V
R
L
= 2k, V
+
= 5V, V
–
= –5V
V
+
= 15V, V
–
= –15V,
±5mA
Load
V
OUT
= 0V, V
+
= 15V, V
–
= –15V
R
L
= 2k, V
+
= 15V, V
–
= –15V
R
L
= 2k, V
+
= 5V, V
–
= –5V
q
q
q
q
q
q
q
q
q
q
MIN
4.5
9
9
TYP
6
12
12
2
2
2
1
600
13
20
0.45
1
30
MAX
10
20
20
UNITS
kΩ
kΩ
kΩ
µs
nV•s
nV•s
mV
P-P
kHz
nV/√Hz
nV/√Hz
µV
RMS
µV
RMS
Hz
V
V
Reference Input
AC Performance (Note 4)
Output Noise Voltage
1/f Noise Corner
Analog Outputs (Note 4)
V
OUT
DAC Output Swing
DAC Output Load Regulation
I
SC
SR
Short-Circuit Current
Slew Rate
±12.6
±2.6
0.02
12
40
20
14
2.4
0.8
0.001
±1
8
60
0
60
110
60
0
1.5
4.5
4.0
4.5
4.5
–16.5
5
10
7.0
6.8
5.5
16.5
– 4.5
20
–12
25
55
40
0.2
LSB/mA
mA
V/µs
V/µs
V
V
µA
pF
ns
ns
ns
ns
ns
ns
µA
mA
mA
V
V
V
Digital Inputs
V
IH
V
IL
I
IN
C
IN
t
DS
t
DH
t
WR
t
LD
t
CLR
t
LWD
I
CC
I
S
V
CC
V
+
V
–
Digital Input High Voltage
Digital Input Low Voltage
Digital Input Current
Digital Input Capacitance
Data to WR Setup Time
Data to WR Hold Time
WR Pulse Width
LD Pulse Width
Clear Pulse Width
WR to LD Delay Time
Supply Current, V
CC
Supply Current, V
+
, V
–
Supply Voltage
Supply Voltage
Supply Voltage
Digital Inputs = 0V or V
CC
±15V
±5V
(Note 4 ) V
IN
= 0V
q
Timing Characteristics
q
q
q
q
q
q
Power Supply
q
q
q
q
q
q
3
LTC1821
ELECTRICAL CHARACTERISTICS
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.
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
.
TYPICAL PERFOR A CE CHARACTERISTICS
Midscale Glitch Impulse
40
30
OUTPUT VOLTAGE (mV)
SIGNAL/(NOISE + DISTORTION) (dB)
C
FEEDBACK
= 30pF
V
REF
= 10V
LD PULSE
5V/DIV
GATED
SETTLING
WAVEFORM
500µV/DIV
20
10
0
–10
–20
– 30
– 40
0
0.2
0.4
0.6
TIME (µs)
0.8
1.0
1821 G01
1nV-s TYPICAL
Bipolar Multiplying Mode
Signal-to-(Noise + Distortion)
vs Frequency, Code = All Zeros
– 40
SIGNAL/(NOISE + DISTORTION) (dB)
– 50
– 60
– 70
– 80
SIGNAL/(NOISE + DISTORTION) (dB)
V
CC
= 5V USING AN LT1468
C
FEEDBACK
= 15pF
REFERENCE = 6V
RMS
– 60
– 70
– 80
500kHz FILTER
– 90
80kHz FILTER
30kHz FILTER
SUPPLY CURRENT (mA)
500kHz FILTER
– 90
80kHz FILTER
30kHz
FILTER
10
100
1k
10k
FREQUENCY (Hz)
100k
1821 G04
–100
–110
4
U W
Full-Scale Setting Waveform
– 40
– 50
– 60
– 70
– 80
Unipolar Multiplying Mode
Signal-to-(Noise + Distortion)
vs Frequency
V
CC
= 5V
C
FEEDBACK
= 30pF
REFERENCE = 6V
RMS
500kHz FILTER
– 90
80kHz FILTER
30kHz FILTER
10
100
1k
10k
FREQUENCY (Hz)
100k
1821 G03
500ns/DIV
V
REF
= –10V
C
FEEDBACK
= 20pF
0V TO 10V STEP
1821 G02
–100
–110
Bipolar Multiplying Mode
Signal-to-(Noise + Distortion)
vs Frequency, Code = All Ones
– 40
– 50
5
V
CC
Supply Current vs Digital
Input Voltage
V
CC
= 5V
ALL DIGITAL INPUTS
TIED TOGETHER
V
CC
= 5V USING AN LT1468
C
FEEDBACK
= 15pF
REFERENCE = 6V
RMS
4
3
2
1
–100
–110
10
100
0
1k
10k
FREQUENCY (Hz)
100k
1821 G05
0
1
3
2
INTPUT VOLTAGE (V)
4
5
1821 G06
LTC1821
TYPICAL PERFOR A CE CHARACTERISTICS
Logic Threshold vs V
CC
Supply
Voltage
3.0
INTEGRAL NONLINEARITY (LSB)
2.5
LOGIC THRESHOLD (V)
2.0
1.5
1.0
0.5
0
0.6
0.4
0.2
0
– 0.2
– 0.4
– 0.6
– 0.8
–1.0
DIFFERENTIAL NONLINEARITY (LSB)
0
1
5
2
3
4
SUPPLY VOLTAGE (V)
Integral Nonlinearity vs Reference
Voltage in Unipolar Mode
1.0
0.8
INTEGRAL NONLINEARITY (LSB)
INTEGRAL NONLINEARITY (LSB)
0.6
0.4
0.2
0
– 0.2
– 0.4
– 0.6
– 0.8
–1.0
–10 – 8 – 6 – 4 – 2 0 2 4 6
REFERENCE VOLTAGE (V)
8
10
DIFFERENTIAL NONLINEARITY (LSB)
Differential Nonlinearity vs
Reference Voltage in Bipolar Mode
1.0
DIFFERENTIAL NONLINEARITY (LSB)
1.0
0.8
INTEGRAL NONLINEARITY (LSB)
0.8
0.6
0.4
0.2
0
– 0.2
– 0.4
– 0.6
– 0.8
–1.0
–10 – 8 – 6 – 4 – 2 0 2 4 6
REFERENCE VOLTAGE (V)
8
10
0.6
0.4
0.2
0
– 0.2
– 0.4
– 0.6
– 0.8
–1.0
2
3
4
5
6
SUPPLY VOLTAGE (V)
7
1821 G14
INTEGRAL NONLINEARITY (LSB)
U W
6
7
1821 G07
Integral Nonlinearity (INL)
1.0
0.8
1.0
0.8
0.6
0.4
0.2
0
– 0.2
– 0.4
– 0.6
– 0.8
–1.0
Differential Nonlinearity (DNL)
0
49152
32768
16384
DIGITAL INPUT CODE
65535
1821 G08
0
49152
32768
16384
DIGITAL INPUT CODE
65535
1821 G09
Integral Nonlinearity vs Reference
Voltage in Bipolar Mode
1.0
0.8
0.6
0.4
0.2
0
– 0.2
– 0.4
– 0.6
– 0.8
–1.0
–10 – 8 – 6 – 4 – 2 0 2 4 6
REFERENCE VOLTAGE (V)
8
10
1.0
0.8
0.6
0.4
0.2
0
– 0.2
– 0.4
– 0.6
– 0.8
Differential Nonlinearity vs
Reference Voltage in Unipolar Mode
–1.0
–10 – 8 – 6 – 4 – 2 0 2 4 6
REFERENCE VOLTAGE (V)
8
10
1821 G10
1821 G11
1821 G12
Integral Nonlinearity vs V
CC
Supply
Voltage in Unipolar Mode
2.0
1.5
1.0
0.5
0
Integral Nonlinearity vs V
CC
Supply
Voltage in Bipolar Mode
V
REF
= 10V
V
REF
= 2.5V
V
REF
= 10V
V
REF
= 2.5V
V
REF
= 10V
V
REF
= 2.5V
V
REF
= 10V
V
REF
= 2.5V
– 0.5
–1.0
–1.5
–2.0
2
3
4
5
6
SUPPLY VOLTAGE (V)
7
1821 G15
1821 G13
5
FPGA/CPLD
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