LTC1456
12-Bit Rail-to-Rail
Micropower DAC
with Clear Input
FEATURES
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DESCRIPTION
The LTC
®
1456 is a complete single supply, rail-to-rail
voltage output, 12-bit digital-to-analog converter (DAC) in
an SO-8 package. It includes a rail-to-rail output buffer
amplifier and an easy-to-use 3-wire cascadable serial
interface. The LTC1456 includes a CLR pin that asynchro-
nously clears the DAC to zero scale.
The LTC1456 has an internal 2.048V reference and a full-
scale output of 4.095V. It operates on a 4.5V to 5.5V
supply, dissipating 2.2mW.
The low power supply current and the space saving SO-8
package make the LTC1456 ideal for battery-powered
applications.
, LTC and LT are registered trademarks of Linear Technology Corporation.
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SO-8 Package
12-Bit Resolution
Buffered True Rail-to-Rail Voltage Output
Asynchronous Clear Input
Built-In Reference
Schmitt Trigger On Clock Input Allows Direct
Optocoupler Interface
Power-On Reset Clears DAC to 0V
3-Wire Cascadable Serial Interface
Maximum DNL Error: 0.5LSB
Low Cost
APPLICATIONS
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Digital Calibration
Industrial Process Control
Automatic Test Equipment
Cellular Telephones
TYPICAL APPLICATION
Functional Block Diagram: 12-Bit Rail-to-Rail DAC with Clear Input
8
2 D
IN
1 CLK
µP
3 CS/LD
12-BIT
SHIFT
REG
AND
DAC
LATCH
V
CC
4.5V TO 5.5V
2.048V
0.5
+
12-BIT
DAC
–
DNL ERROR (LSB)
V
OUT
7
RAIL-TO-RAIL
VOLTAGE
OUTPUT
4 D
OUT
TO
OTHER
DACS
6 CLR
POWER-ON
RESET
GND
5
1456 TA01
U
U
U
Differential Nonlinearity
vs Input Code
0
–0.5
0
512 1024 1536 2048 2560 3072 3584 4095
CODE
1456 TA02
1
LTC1456
ABSOLUTE
MAXIMUM
RATINGS
V
CC
to GND .............................................. – 0.5V to 7.5V
Logic Inputs to GND ................................ – 0.5V to 7.5V
V
OUT
.............................................. – 0.5V to V
CC
+ 0.5V
Maximum Junction Temperature ......... – 65°C to 125°C
Operating Temperature Range
LTC1456C ............................................ 0°C to 70°C
LTC1456I ........................................ – 40°C to 85°C
Storage Temperature Range ................ – 65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
PACKAGE/ORDER I FOR ATIO
TOP VIEW
CLK 1
D
IN
2
CS/LD 3
D
OUT
4
N8 PACKAGE
8-LEAD PDIP
8
7
6
5
V
CC
V
OUT
CLR
GND
ORDER PART
NUMBER
LTC1456CN8
LTC1456IN8
LTC1456CS8
LTC1456IS8
S8 PART MARKING
1456
1456I
S8 PACKAGE
8-LEAD PLASTIC SO
T
JMAX
= 125°C,
θ
JA
= 100°C/W (N8)
T
JMAX
= 125°C,
θ
JA
= 150°C/W (S8)
Consult factory for Military grade parts.
ELECTRICAL CHARACTERISTICS
V
CC
= 4.5V to 5.5V, V
OUT
unloaded, T
A
= T
MIN
to T
MAX
, unless otherwise noted.
SYMBOL
DAC
Resolution
DNL
INL
V
OS
V
OS
TC
V
FS
V
FS
TC
Differential Nonlinearity
Integral Nonlinearity
Offset Error
Offset Error Temperature
Coefficient
Full-Scale Voltage
Full-Scale Voltage
Temperature Coefficient
Positive Supply Voltage
Supply Current
Short-Circuit Current Low
Short-Circuit Current High
Output Impedance to GND
AC Performance
Voltage Output Slew Rate
Voltage Output Settling Time
Digital Feedthrough
(Note 2)
(Notes 2, 3) to
±0.5LSB
q
q
PARAMETER
CONDITIONS
MIN
12
TYP
MAX
UNITS
Bits
Guaranteed Monotonic (Note 1)
T
A
= 25°C
(Note 1)
T
A
= 25°C
q
q
q
±0.5
±3.5
±4
±12
±18
±15
µV/°C
4.125
4.145
V
V
ppm/°C
T
A
= 25°C
q
4.065
4.045
4.095
4.095
±
24
Power Supply
V
CC
I
CC
For Specified Performance
(Note 4)
V
OUT
Shorted to GND
V
OUT
Shorted to V
CC
Input Code = 0
q
q
4.5
430
5.5
650
120
120
40
120
Op Amp DC Performance
q
q
q
0.4
1.0
14
0.3
nV • s
2
U
LSB
LSB
LSB
mV
mV
V
µA
mA
mA
Ω
V/µs
µs
W
U
U
W W
W
LTC1456
ELECTRICAL CHARACTERISTICS
V
CC
= 4.5V to 5.5V, V
OUT
unloaded, T
A
= T
MIN
to T
MAX
, unless otherwise noted.
SYMBOL
Digital I/O
V
IH
V
IL
V
OH
V
OL
I
LEAK
C
IN
Switching
t
1
t
2
t
3
t
4
t
5
t
6
t
7
t
8
t
9
t
10
D
IN
Valid to CLK Setup
D
IN
Valid to CLK Hold
CLK High Time
CLK Low Time
CS/LD Pulse Width
LSB CLK to CS/LD
CS/LD Low to CLK
D
OUT
Output Delay
CLK Low to CS/LD Low
CLR Pulse Width
C
LOAD
= 15pF, V
CC
= 5V
q
q
q
q
q
q
q
q
q
q
PARAMETER
Digital Input High Voltage
Digital Input Low Voltage
Digital Output High Voltage
Digital Output Low Voltage
Digital Input Leakage
Digital Input Capacitance
CONDITIONS
q
q
MIN
2.4
TYP
MAX
UNITS
V
0.8
V
CC
– 1.0
0.4
±10
10
40
0
40
40
50
40
20
150
20
65
V
V
V
µA
pF
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
I
OUT
= – 1mA, D
OUT
Only
I
OUT
= 1mA, D
OUT
Only
V
CC
= 5V, V
IN
= GND to V
CC
Guaranteed by Design. Not Subject to Test.
q
q
q
q
The
q
denotes specifications which apply over the full operating
temperature range.
Note 1:
Nonlinearity is defined from the first code that is greater than or
equal to the maximum offset specification to code 4095 (full scale).
Note 2:
Load is 5kΩ in parallel with 100pF.
Note 3:
DAC switched between all 1s and the code corresponding to V
OS
for the part.
Note 4:
Digital inputs at 0V or V
CC
.
3
LTC1456
TYPICAL PERFORMANCE CHARACTERISTICS
Differential Nonlinearity (DNL)
0.5
0.4
0.3
INL ERROR (LSB)
2.0
1.6
1.2
0.8
0.4
0
– 0.4
– 0.8
–1.2
–1.6
– 2.0
0.2
DNL (LSB)
0.1
0
– 0.1
– 0.2
– 0.3
– 0.4
– 0.5
0
512 1024 1536 2048 2560 3072 3584 4095
CODE
1456 G01
V
CC
– V
OUT
(V)
Minimum Output Voltage
vs Output Sink Current
700
1.750
OUTPUT PULL-DOWN VOLTAGE (mV)
125°C
600
500
25°C
400
300
200
100
0
0
2
8 10 12 14 16 18 20
4 6
OUTPUT SINK CURRENT (mA)
1456 G04
SUPPLY CURRENT (mA)
OUTPUT SWING (V)
– 55°C
Output Swing vs Load Resistance
4.5
CODE: ALL 1s
4.0
0.8
3.5
OUTPUT SWING (V)
SUPPLY CURRENT (µA)
OFFSET VOLTAGE (mV)
3.0
2.5
2.0
1.5
1.0
0.5
0
10
100
1k
LOAD RESISTANCE (Ω)
10k
1456 G07
4
U W
R
L
Integral Nonlinearity (INL)
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
0
512 1024 1536 2048 2560 3072 3584 4095
CODE
1456 G02
Minimum Supply Headroom for
Full Output Swing vs Load Current
∆V
OUT
< 1LSB
CODE: ALL 1s
V
OUT
= 4.095V
0
5
20
15
10
LOAD CURRENT (mA)
25
30
1456 G03
Supply Current
vs Logic Input Voltage
4.5
ALL DIGITAL INPUTS
TIED TOGETHER
1.615
1.480
1.345
1.210
1.075
0.940
0.805
0.670
0.535
0.400
0
0.5 1
1.5 2 2.5 3 3.5 4
LOGIC INPUT VOLTAGE (V)
4.5 5
1456 G05
Output Swing vs Load Resistance
CODE: ALL 0s
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
10
100
1k
LOAD RESISTANCE (Ω)
10k
1456 G06
V
CC
R
L
Offset Voltage vs Temperature
0.9
Supply Current vs Temperature
550
540
530
520
510
500
490
480
470
460
V
CC
= 4.5V
V
CC
= 5V
V
CC
= 5.5V
0.7
0.6
0.5
0.4
0.3
– 55
– 25
5
35
65
TEMPERATURE (°C)
95
125
1456 G08
450
– 55
– 25
35
65
5
TEMPERATURE (°C)
95
125
1456 G09
LTC1456
PIN FUNCTIONS
CLK (Pin 1):
The Serial Interface Clock. Internal Schmitt
trigger on this input allows direct optocoupler interface.
D
IN
(Pin 2):
The Serial Interface Data. Data on the D
IN
pin
is latched into the shift register on the rising edge of the
serial clock.
CS/LD (Pin 3):
The Serial Interface Enable and Load
Control. When CS/LD is low the CLK signal is enabled, so
the data can be clocked in. When CS/LD is pulled high,
data is loaded from the shift register into the DAC
register, updating the DAC output. When CS/LD is high
the CLK is disabled internally.
D
OUT
(Pin 4):
The Output of the Shift Register Which
Becomes Valid on the Rising Edge of the Serial Clock.
GND (Pin 5):
Ground.
CLR (Pin 6):
The Clear Input. When pulled low, this pin
asynchronously clears the internal shift and DAC registers
to zero scale. Should be tied high for normal operation.
V
OUT
(Pin 7):
The Buffered DAC Output.
V
CC
(Pin 8):
The Positive Supply Input. 4.5V
≤
V
CC
≤
5.5V.
Requires a bypass capacitor to ground.
BLOCK DIAGRA
CLK 1
D
IN
2
12-BIT
SHIFT
REGISTER
CS/LD 3
D
OUT
4
TI I G DIAGRA
CLK
t
9
D
IN
B0
PREVIOUS WORD
CS/LD
D
OUT
W
W
U
U
UW
U
2.048V
8 V
CC
LD
DAC
REGISTER
12-BIT
DAC
+
7 V
OUT
–
POWER-ON
RESET
6 CLR
5 GND
1146 BD
t
1
t
2
t
6
t
7
t
4
t
3
B11
MSB
B10
B1
B0
LSB
t
8
t
5
B11
PREVIOUS WORD
B10
B1
B0
B11
CURRENT WORD
1456 TD
5
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