Features
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LTC2668
16-Channel 16-/12-Bit ±10V
V
OUT
SoftSpan DACs with
10ppm/°C Max Reference
Description
The
LTC
®
2668
is a family of 16-channel, 16-/12-bit ±10V
digital-to-analog converters with integrated precision
references. They are guaranteed monotonic and have
built-in rail-to-rail output buffers. These SoftSpan™ DACs
offer five output ranges up to ±10V. The range of each
channel is independently programmable, or the part can
be hardware-configured for operation in a fixed range.
The integrated 2.5V reference is buffered separately to each
channel; an external reference can be used for additional
range options. The LTC2668 also includes A/B toggle
capability via a dedicated pin or software toggle command.
The SPI/Microwire-compatible 3-wire serial interface
operates on logic levels as low as 1.71V at clock rates
up to 50MHz.
L,
LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
SoftSpan is a trademark of Linear Technology Corporation. All other trademarks are the property
of their respective owners.
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Precision Reference 10ppm/°C Max
Independently Programmable Output Ranges:
0V to 5V, 0V to 10V, ±2.5V, ±5V, ±10V
Full 16-Bit/12-Bit Resolution at All Ranges
Maximum INL Error: ±4LSB at 16 Bits
A/B Toggle via Software or Dedicated Pin
16:1 Analog Multiplexer
Guaranteed Monotonic Over Temperature
Internal or External Reference
Outputs Drive ±10mA Guaranteed
1.8V to 5V SPI Serial interface
6mm × 6mm 40-Lead QFN Package
applications
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Optical Networking
Instrumentation
Data Acquisition
Automatic Test Equipment
Process Control and Industrial Automation
Block Diagram
REFCOMP 34
OVRTMP
38
RGSTR A
GND
14, 37
REFLO
13, 35
V
OUT0
2
V
OUT1
3
V
OUT2
4
V
OUT3
5
V
OUT4
6
V
OUT5
7
V
OUT6
8
V
OUT7
9
DAC 7
SPAN
SPAN
V
REF
REGISTER
V
REF
REGISTER
RGSTR A
V
REF
REGISTER
INTERNAL REFERENCE
33 REF
36 AVP
V
+
10, 31
V
–
11, 32
Integral Nonlinearity (LTC2668-16)
4
3
2
INL (LSB)
1
0
–1
–2
–3
–4
0
16384
32768
CODE
49152
65535
2668 TA01b
±10V RANGE
MUX
RGSTR B
RGSTR B
MUX
DAC 0
SPAN
SPAN
DAC 15
SPAN
SPAN
30 V
OUT15
29 V
OUT14
28 V
OUT13
27 V
OUT12
• • •
• • •
• • •
• • •
• • •
• • •
• • •
• • •
RGSTR A
RGSTR A
V
REF
REGISTER
26 V
OUT11
25 V
OUT10
24 V
OUT9
MUX
RGSTR B
RGSTR B
MUX
DAC 8
SPAN
SPAN
23 V
OUT8
21
CLR
15
LDAC
20 TGP
39 MSP0
CS/LD
16
SCK 17
SDI 19
SDO 18
MUX 12
CONTROL LOGIC
DECODE
POWER-ON RESET
32-BIT SHIFT REGISTER
MONITOR MUX
40 MSP1
1
MSP2
TOGGLE SELECT REGISTER
22 OVP
2668 TA01a
2668fa
For more information
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1
LTC2668
aBsolute maximum ratings
(Notes 1, 2)
pin conFiguration
TOP VIEW
REFCOMP
OVRTMP
REFLO
MSP1
MSP0
GND
AVP
Analog Supply Voltage (AVP) ....................... –0.3V to 6V
Digital I/O Voltage (OVP).............................. –0.3V to 6V
REFLO ....................................................... –0.3V to 0.3V
V
+
............................................................ –0.3V to 16.5V
V
–
.. ..........................................................–16.5V to 0.3V
CS/LD,
SCK, SDI,
LDAC, CLR,
TGP .............. –0.3V to 6V
MSP0, MSP1, MSP2 ....... –0.3V to Min (AVP + 0.3V, 6V)
V
OUT0
to V
OUT15
, MUX...V
–
– 0.3V to V
+
+ 0.3V (Max ±16.5V)
REF, REFCOMP ............... –0.3V to Min (AVP + 0.3V, 6V)
SDO ................................–0.3V to Min (OVP + 0.3V, 6V)
OVRTMP
....................................................... –0.3V to 6V
Operating Temperature Range
LTC2668C ................................................ 0°C to 70°C
LTC2668I .............................................–40°C to 85°C
LTC2668H .......................................... –40°C to 125°C
Maximum Junction Temperature .......................... 150°C
Storage Temperature Range .................. –65°C to 150°C
REF
V
–
SDI
40 39 38 37 36 35 34 33 32 31
MSP2 1
V
OUT0
2
V
OUT1
3
V
OUT2
4
V
OUT3
5
V
OUT4
6
V
OUT5
7
V
OUT6
8
V
OUT7
9
V
+
10
11 12 13 14 15 16 17 18 19 20
CS/LD
MUX
SCK
REFLO
GND
LDAC
SDO
TGP
V
–
41
V
–
30
V
OUT15
29
V
OUT14
28
V
OUT13
27
V
OUT12
26
V
OUT11
25
V
OUT10
24
V
OUT9
23
V
OUT8
22 OVP
21
CLR
UJ PACKAGE
40-LEAD (6mm
×
6mm) PLASTIC QFN
T
JMAX
= 150°C,
θ
JA
= 33°C/W,
θ
JC
= 2°C/W
EXPOSED PAD IS V
–
, MUST BE SOLDERED TO PCB
V
+
2
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For more information
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LTC2668
orDer inFormation
LTC2668
C
UJ
16
#TR PBF
LEAD FREE DESIGNATOR
PBF = Lead Free
TAPE AND REEL
TR = 2000-Piece Tape and Reel
RESOLUTION
16 = 16-Bit
12 = 12-Bit
PACKAGE TYPE
UJ = 40-Lead QFN
TEMPERATURE GRADE
C = Commercial Temperature Range (0°C to 70°C)
I = Industrial Temperature Range (–40°C to 85°C)
H = Automotive Temperature Range (–40°C to 125°C)
PRODUCT PART NUMBER
Consult LTC Marketing for information on nonstandard lead based finish parts.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/
proDuct selection guiDe
LEAD FREE FINISH
LTC2668CUJ-16#PBF
LTC2668IUJ-16#PBF
LTC2668HUJ-16#PBF
LTC2668CUJ-12#PBF
LTC2668IUJ-12#PBF
LTC2668HUJ-12#PBF
TAPE AND REEL
LTC2668CUJ-16#TRPBF
LTC2668IUJ-16#TRPBF
LTC2668HUJ-16#TRPBF
LTC2668CUJ-12#TRPBF
LTC2668IUJ-12#TRPBF
LTC2668HUJ-12#TRPBF
PART MARKING
LTC2668UJ-16
LTC2668UJ-16
LTC2668UJ-16
LTC2668UJ-12
LTC2668UJ-12
LTC2668UJ-12
PACKAGE DESCRIPTION
40-Lead (6mm × 6mm) QFN
40-Lead (6mm × 6mm) QFN
40-Lead (6mm × 6mm) QFN
40-Lead (6mm × 6mm) QFN
40-Lead (6mm × 6mm) QFN
40-Lead (6mm × 6mm) QFN
TEMPERATURE RANGE
0°C to 70°C
–40°C to 85°C
–40°C to 125°C
0°C to 70°C
–40°C to 85°C
–40°C to 125°C
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For more information
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3
LTC2668
electrical characteristics
LTC2668-16/LTC2668-12
LTC2668-12
SYMBOL
PARAMETER
Resolution
Monotonicity
DNL
INL
Differential Nonlinearity
Integral Nonlinearity
All Ranges (Note 3)
All Ranges (Note 3)
All Ranges (Note 3)
V
+
/V
–
= ±15V
V
–
= GND (Note 3)
C-Grade, I-Grade
H-Grade
0V to 5V Range
0V to 10V Range
All Unipolar Ranges
All Unipolar Ranges,
V
–
= GND
All Bipolar Ranges
All Bipolar Ranges
All Ranges, External Reference
AVP = 5V, ±10%
V
+
/V
–
= ±15V, ±5%
CONDITIONS
To V
–
(Unloaded, V
–
= GND)
To V
+
(Unloaded, V
+
= 5V)
To V
–
(–10mA ≤ I
OUT
≤ 10mA)
To V
+
(–10mA ≤ I
OUT
≤ 10mA)
–10mA ≤ I
OUT
≤ 10mA
(Note 4)
–10mA ≤ I
OUT
≤ 10mA
(Note 4)
Due to Full-Scale Output Change
Due to Load Current Change
Due to Powering Down (per Channel)
AVP = 5.5V, V
+
/V
–
= ±15.75V, V
REF
= 2.5V,
±10V Output Range
Code: Zero-Scale; Forcing Output to GND
Code: Full-Scale; Forcing Output to GND
Reference
Reference Output Voltage
Reference Temperature Coefficient
Reference Line Regulation
Reference Short-Circuit Current
(Note 7)
AVP ±10%
AVP = 5.5V, Forcing Output to GND
l
l
l
l
l
l
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. AVP = 5V, OVP = 5V, V
+
= 15V, V
–
= –15V, V
REF
= 2.5V, V
OUT
unloaded
unless otherwise specified.
LTC2668-16
MIN
16
16
±0.05
±0.2
±0.2
±0.2
±1
±2
1
2
4
±0.5
±1
±1
±1
±2
±4
±0.2
±2.2
±2.2
±2.2
±1
±2
1
2
4
±1
±4
±4
±5
±2
±4
TYP
MAX
UNITS
Bits
Bits
LSB
LSB
LSB
LSB
mV
mV
ppm/°C
mV
%FSR
ppm/°C
%FSR
ppm/°C
LSB/V
LSB/V
MAX
UNITS
V
V
V
V
µV/mA
Ω
µV
µV/mA
µV
CONDITIONS
l
l
l
l
l
l
l
l
MIN
12
12
TYP
MAX
DC Performance
V
OS
Unipolar Offset Error
V
OS
Temperature Coefficient
ZSE
BZE
GE
PSR
Single-Supply Zero-Scale Error
Bipolar Zero Error
BZE Temperature Coefficient
Gain Error
Gain Temperature Coefficient
Power Supply Rejection
All Ranges
±0.02 ±0.08
1
±0.02 ±0.08
2
0.1
0.001
MIN
TYP
±0.02 ±0.08
1
±0.02 ±0.08
2
1
0.01
SYMBOL PARAMETER
V
OUT
Output Voltage Swing
V
–
+ 0.004
V
+
– 0.004
l
l
l
l
V
+
– 1.4
78
0.078
±1
±2
±4
V
–
+ 1.4
150
0.15
Load Regulation
R
OUT
DC Output Impedance
DC Crosstalk (Note 5)
0V to 5V Range
I
SC
V
+
/V
–
Short-Circuit Output Current
(Note 6)
16
–40
2.495
2.5
±2
50
42
–14.5
2.505
±10
5
mA
mA
V
ppm/°C
µV/V
mA
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4
For more information
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LTC2668
electrical characteristics
SYMBOL PARAMETER
REFCOMP Pin Short-Circuit Current
Reference Load Regulation
Reference Output Voltage Noise
Density
Reference Input Range
Reference Input Current
Reference Input Capacitance (Note 9)
Power Supply
AVP
V
+
V
–
OVP
I
AVP
I
S
I
OVP
Analog Supply Voltage
Analog Positive Supply
Analog Negative Supply
Digital I/O Supply Voltage
Supply Current AVP
Supply Current V
+
/V
–
Supply Current OVP (Note 12)
AVP Shutdown Supply Current
V
+
Shutdown Supply Current
V
–
Shutdown Supply Current
Monitor Mux
Monitor Mux DC Output Impedance
Monitor Mux Leakage Current
Monitor Mux Output Voltage Range
Monitor Mux Continuous Current
(Note 9)
AC Performance
t
SET
Settling Time (Notes 9, 13)
0V to 5V or ±2.5V Span, ±5V Step
Settling Time (Notes 9, 13)
0V to 10V or ±5V Span, ±10V Step
Settling Time (Notes 9, 13)
±10V Span, ±20V Step
SR
Voltage Output Slew Rate
Capacitive Load Driving
Glitch Impulse (Note 14)
DAC-to-DAC Crosstalk (Note 15)
e
n
Output Voltage Noise
0V to 5V Output Span,
Internal Reference
At Mid-Scale Transition, 0V to 5V Range
Due to Full-Scale Output Change
Density at f = 1kHz
Density at f = 10kHz
0.1Hz to 10Hz, Internal Reference
0.1Hz to 200kHz, Internal Reference
±0.024% (±1LSB at 12 Bits)
±0.0015% (±1LSB at 16 Bits)
±0.024% (±1LSB at 12 Bits)
±0.0015% (±1LSB at 16 Bits)
±0.024% (±1LSB at 12 Bits)
±0.0015% (±1LSB at 16 Bits)
4.5
9
8
9
15.5
20.5
5
1000
8
6
90
80
1.7
55
µs
µs
µs
µs
µs
µs
V/µs
pF
nV
•
s
nV
•
s
nV/√Hz
nV/√Hz
µV
RMS
µV
RMS
Monitor Mux Disabled (High Impedance)
Monitor Mux Selected to DAC Channel
l
l
l
l
l
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. AVP = 5V, OVP = 5V, V
+
= 15V, V
–
= –15V, V
REF
= 2.5V, V
OUT
unloaded
unless otherwise specified.
CONDITIONS
AVP = 5.5V, Forcing Output to GND
AVP = 5V ± 10%, I
OUT
= 100µA Sourcing
C
REFCOMP
= C
REF
= 0.1µF, at f = 10kHz
External Reference Mode (Note 8)
External Reference
l
l
l
l
MIN
TYP
140
32
MAX
200
UNITS
µA
mV/mA
nV/√Hz
0.5
0.001
40
4.5
4.5
–15.75
1.71
5.4
9.4
4.6
8
0.02
1
35
–60
–27
2.2
0.02
V
–
0
AVP – 1.75
1
V
µA
pF
5.5
15.75
–4.5
AVP + 0.3
6.5
12
6.5
9.5
1
3
70
V
V
V
V
V
mA
mA
mA
mA
µA
µA
µA
µA
kΩ
V
–
Not Tied to GND
V
–
Tied to GND
AVP = 5V, Unipolar Ranges (Note 10)
AVP = 5V, Bipolar Ranges (Note 10)
Unipolar Ranges (Code = 0)
Bipolar Ranges (Note 11)
OVP = 5V
OVP = AVP = 5V, V
+
/V
–
= ±15V
OVP = AVP = 5V, V
+
/V
–
= ±15V
OVP = AVP = 5V, V
+
/V
–
= ±15V
l
l
l
l
l
l
l
l
l
l
1
V
+
– 1.4
±1
µA
V
mA
2668fa
For more information
www.linear.com/LTC2668
5
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