LTC1257
Complete Single Supply
12-Bit Voltage Output
DAC in SO-8
FEATURES
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DESCRIPTION
The LTC
®
1257 is a complete single supply, 12-bit voltage
output D/A converter (DAC) in an SO-8 package. The
LTC1257 includes an output buffer amplifier, 2.048V volt-
age reference and an easy to use 3-wire cascadable serial
interface. An external reference can be used to override
the internal reference and extend the output voltage range
to 12V. The power supply current is a low 350µA when
operating from a 5V supply, making the LTC1257 ideal
for battery-powered applications. The space-saving 8-pin
SO package and operation with no external components
provide the smallest 12-bit D/A system available.
L,
LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
8-Pin SO Package
Buffered Voltage Output
Built-In 2.048V Reference
500µV/LSB with 2.048V Full Scale
1/2LSB Max DNL Error
Guaranteed 12-Bit Monotonic
3-Wire Cascadable Serial Interface
Wide Single Supply Range: V
CC
= 4.75V to 15.75V
Low Power: I
CC
Typ = 350µA with 5V Supply
APPLICATIONS
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Digital Offset/Gain Adjustment
Industrial Process Control
Automatic Test Equipment
TYPICAL APPLICATION
Daisy-Chained Control Outputs
5V
0.5
Differential Nonlinearity
vs Input Code
0.1µF
CONTROL OUTPUT 1
V
CC
V
OUT
LTC1257
GND V
REF
D
IN
LOAD
D
OUT
µP
DNL ERROR (LSBs)
CLK
0.0
0.1µF
CONTROL OUTPUT 2
V
CC
V
OUT
LTC1257
GND V
REF
D
IN
CLK
LOAD
D
OUT
TO NEXT DAC
1257 TA01
–0.5
0
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CODE
1257 TA05
1257fc
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LTC1257
ABSOLUTE MAXIMUM RATINGS
(Note 1)
V
CC
to GND ............................................. –0.5V to 16.5V
TTL Input Voltage .......................... –0.5V to V
CC
+ 0.5V
V
OUT
................................................ –0.5V to V
CC
+ 0.5V
REF ................................................. –0.5V to V
CC
+ 0.5V
Operating Temperature Range
LTC1257C ................................................ 0°C to 70°C
LTC1257I............................................. –40°C to 85°C
Maximum Junction Temperature
Plastic Package ...................................... –65°C to 125°C
Storage Temperature Range .................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec)................... 300°C
PIN CONFIGURATION
TOP VIEW
CLK 1
D
IN
2
LOAD
3
D
OUT
4
N8 PACKAGE
8-LEAD PDIP
T
JMAX
= 125°C,
θ
JA
= 100°C/W
8 V
CC
7 V
OUT
6 REF
5 GND
CLK 1
D
IN
2
LOAD
3
D
OUT
4
TOP VIEW
8 V
CC
7 V
OUT
6 REF
5 GND
S8 PACKAGE
8-LEAD PLASTIC SO
T
JMAX
= 125°C,
θ
JA
= 150°C/W
ORDER INFORMATION
LEAD FREE FINISH
LTC1257CN8#PBF
LTC1257IN8#PBF
LTC1257CS8#PBF
LTC1257IS8#PBF
TAPE AND REEL
LTC1257CN8#TRPBF
LTC1257IN8#TRPBF
LTC1257CS8#TRPBF
LTC1257IS8#TRPBF
PART MARKING
LTC1257CN8
LTC1257IN8
1257
1257I
PACKAGE DESCRIPTION
8-Lead PDIP
8-Lead PDIP
8-Lead Plastic SO
8-Lead Plastic SO
TEMPERATURE RANGE
0°C to 70°C
–40°C to 85°C
0°C to 70°C
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
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/
The
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denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= T
MIN
to T
MAX
. V
CC
= 4.75V to 15.75V, internal or external reference
(2.475V ≤ V
REF
≤ V
CC
– 2.7V), unless otherwise noted.
SYMBOL
DAC
DNL
INL
PARAMETER
Resolution
Differential Nonlinearity
Integral Nonlinearity
CONDITIONS
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ELECTRICAL CHARACTERISTICS
MIN
12
TYP
MAX
UNITS
Bits
LSB
LSB
LSB
Guaranteed Monotonic (Note 4)
LTC1257C (Note 4)
LTC1257I (Note 4)
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±0.5
±3.5
±4.0
1257fc
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LTC1257
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= T
MIN
to T
MAX
. V
CC
= 4.75V to 15.75V, internal or external reference
(2.475V ≤ V
REF
≤ V
CC
– 2.7V), unless otherwise noted.
SYMBOL
OFF
PARAMETER
Offset Error
CONDITIONS
When Using Internal Reference, LTC1257C
When Using Internal Reference, LTC1257I
When Using External Reference, LTC1257C
When Using External Reference, LTC1257I
When Using Internal Reference (Note 2)
When Using External Reference (Note 2)
(Note 2)
I
REF
= 0, LTC1257C
I
RE
F = 0, LTC1257I
I
REF
= 0
I
REF
= 0, LTC1257C
I
REF
= 0, LTC1257I
0µA ≤ I
REF
≤ 100µA
V
CC
> V
REF
+ 2.7V
(Note 2)
V
REF
Shorted to GND
For Specified Performance
4.75V ≤ V
CC
≤ 5.25V
4.75V ≤ V
CC
≤ 15.75V
V
OUT
Shorted to GND
V
OUT
Shorted to V
CC
Input Code = 0
5kΩ in Parallel with 100pF
To ±1/2LSB, 5kΩ in Parallel with 100pF, V
CC
= 4.75V
(Notes 2, 3)
MIN
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ELECTRICAL CHARACTERISTICS
TYP
OFF
TC
Offset Error Tempco
Gain Error
Gain Error Tempco
±0.02
±15
0.5
±0.01
2.028
2.018
2.048
±0.06
MAX
±8
±10
±4
±5
±0.066
±30
±2
±0.02
2.068
2.078
±0.4
±0.7
±1
12
18
90
UNITS
LSB
LSB
mV
mV
LSB/°C
µV/°C
LSB
LSB/°C
V
V
LSB/°C
LSB/V
LSB/V
LSB
V
kΩ
pF
mA
V
µA
µA
mA
mA
Ω
V/µs
µs
nV/s
V
V
V
V
µA
pF
ns
ns
ns
ns
Reference
Reference Output Voltage
Reference Output Tempco
Reference Line Regulation
Reference Load Regulation
Reference Input Range
Reference Input Resistance
Reference Input Capacitance
Short-Circuit Current
Power Supply
Positive Supply Voltage
V
CC
Supply Current
I
CC
Op Amp DC Performance
Short-Circuit Current Low
Short-Circuit Current High
Output Impedance to GND
AC Performance
Voltage Output Slew Rate
Voltage Output Settling Time
Digital Feedthrough
Digital I/O
Digital Input High Voltage
V
IH
Digital Input Low Voltage
V
IL
Digital Output High Voltage
V
OH
Digital Output Low Voltage
V
OL
Digital Input Leakage
I
LEAK
Digital Input Capacitance
C
IN
Switching (Note 2)
D
IN
Valid to CLK Setup
t
1
D
IN
Valid to CLK Hold
t
2
CLK High Time
t
3
CLK Low Time
t
4
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2.475
8
14
15
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4.75
350
800
15.75
600
1500
60
60
500
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250
1.0
6
50
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2.4
0.8
V
CC
– 1
0.4
±10
10
100
25
350
350
I
OUT
= –1mA, D
OUT
Only
I
OUT
= 1mA, D
OUT
Only
V
IN
= GND to V
CC
(Note 2)
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1257fc
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LTC1257
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= T
MIN
to T
MAX
. V
CC
= 4.75V to 15.75V, internal or external reference
(2.475V ≤ V
REF
≤ V
CC
– 2.7V), unless otherwise noted.
SYMBOL
t
5
t
6
t
7
t
8
f
CLK
PARAMETER
LOAD
Pulse Width
LSB CLK to
LOAD
LOAD
High to CLK
D
OUT
Output Delay
Maximum Clock Frequency
CONDITIONS
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ELECTRICAL CHARACTERISTICS
C
LOAD
= 15pF
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MIN
150
0
0
35
TYP
MAX
150
1.4
UNITS
ns
ns
ns
ns
MHz
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2:
Guaranteed by design; not subject to test.
Note 3:
DAC switched from all 1s to all 0s, and all 0s to all 1s code.
Note 4:
Guaranteed with internal V
REF
or with external V
REF
range of
2.475V to 12V. Tested at 10V.
TYPICAL PERFORMANCE CHARACTERISTICS
Minimum Supply Voltage
vs Load Current #1
5.0
4.8
MINIMUM SUPPLY VOLTAGE (V)
4.6
4.4
4.2
4.0
3.8
3.6
3.4
3.2
3.0
0.01
0.1
1
OUTPUT LOAD CURRENT (mA)
10
1257 G01
Minimum Supply Voltage
vs Load Current #2
15.0
MINIMUM SUPPLY VOLTAGE (V)
0.38
V
REF
= 10V
V
OUT
= FULL SCALE
T
A
= 25°C
SUPPLY CURRENT (mA)
0.37
0.36
0.35
0.34
14.5
14.0
13.5
13.0
12.5
12.0
11.5
11.0
0.01
0.1
1
OUTPUT LOAD CURRENT (mA)
10
1257 G02
Supply Current vs Temperature
V
REF
= INTERNAL
V
OUT
= FULL SCALE
T
A
= 25°C
V
CC
= 5.25V
V
CC
= 5V
V
CC
= 4.75V
0.33
0.32
0.31
–50 –25
50
25
75
0
TEMPERATURE (°C)
100
125
1257 G03
Supply Current
vs Logic Input Voltage
0.59
V
CC
= 5V
T
A
= 25°C
OUTPUT VOLTAGE SWING (V)
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.34
0
1
3
2
LOGIC VOLTAGE (V)
4
5
1257 G04
Output Swing vs Load Resistance
1000
OUTPUT PULL-DOWN VOLTAGE (mV)
V
CC
= 5V
ZERO SCALE
R
L
TIED TO V
CC
FULL SCALE
R
L
TIED TO GND
Pull-Down Voltage
vs Output Sink Current Capability
0.54
SUPPLY CURRENT (mA)
100
0.49
10
0.44
HOT
COLD
ROOM
0.39
1
0
10
100
1k
LOAD RESISTANCE ( )
10k
1257 G05
0.1
1
10
100
OUTPUT SINK CURRENT (µA)
1000
1257 G06
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LTC1257
TYPICAL PERFORMANCE CHARACTERISTICS
Full-Scale Voltage
vs Temperature
2.0495
2.0490
FULL-SCALE VOLTAGE (V)
2.0485
2.0480
2.0475
2.0470
2.0465
–50 –25
V
CC
= 5V
INTERNAL REFERENCE
ZERO-SCALE VOLTAGE (mV)
0.9
0.8
0.7
ERROR (LSB)
0.6
0.5
0.4
0.3
0.2
0.1
50
25
75
0
TEMPERATURE (°C)
100
125
0
–50
–25
0
25
50
75
TEMPERATURE (°C)
100
125
V
CC
= 5V
INTERNAL REFERENCE
Zero-Scale Voltage
vs Temperature
2.0
1.6
1.2
0.8
0.4
0
–0.4
–0.8
–1.2
–1.6
–2.0
Integral Nonlinearity (INL)
V
CC
= 5V
INTERNAL REFERENCE
T
A
= 25°C
0
512 1024 1536 2048 2560 3072 3584 4096
CODE
1257 G09
1257 G07
1257 G08
Differential Nonlinearity (DNL)
REFERENCE COMPENSATION RESISTANCE ( )
0.5
70
60
50
Reference Compensation
Resistance vs C
L
Broadband Noise
CODE = FFF
H
BW = 3Hz TO 1MHz
GAIN = 1100×
DNL ERROR (LSBs)
0.0
30
20
10
0
0.01
0.1
1
C
L
(µF)
10
100
1257 G11
–0.5
0
512 1024 1536 2048 2560 3072 3584 4098
CODE
1257 TA05
0.1V/DIV
40
TIME = 5ms/DIV
1257 G12
PIN FUNCTIONS
CLK (Pin 1):
The TTL level input for the serial interface clock.
D
IN
(Pin 2):
The TTL level input for the serial interface
data. Data on the D
IN
pin is latched into the shift register
on the rising edge of the serial clock.
LOAD (Pin 3):
The TTL level input for the serial interface
load control. Data is loaded from the shift register into the
DAC register, thus updating the DAC output when
LOAD
is pulled low. The DAC register is transparent as long as
LOAD
is held low.
D
OUT
(Pin 4):
The output of the shift register which becomes
valid on the rising edge of the serial clock. The D
OUT
pin
is driven from GND to V
CC
by an internal CMOS inverter.
Multiple LTC1257s may be cascaded by connecting the
D
OUT
pin to the D
IN
pin of the next chip.
GND (Pin 5):
Ground.
REF (Pin 6):
The output of the 2.048V reference and the
input to the DAC resistor ladder. An external reference
with voltage from 2.475V to V
CC
– 2.7V may be used to
override the internal reference.
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