LTC1446/LTC1446L
Dual 12-Bit Rail-to-Rail
Micropower DACs in SO-8
FEATURES
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DESCRIPTIO
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Dual DACs with 12-Bit Resolution
SO-8 Package
Rail-to-Rail Output Amplifiers
Internal Reference
Maximum DNL Error: 0.5LSB
3V Operation (LTC1446L): I
CC
= 650µA Typ
5V Operation (LTC1446): I
CC
= 1000µA Typ
Settling Time: 14µs to
±0.5LSB
Power-On Reset Clears DACs to 0V
3-Wire Cascadable Serial Interface with 500kHz
Update Rate
Schmitt Trigger On Input Allows Direct
Optocoupler Interface
Low Cost
The LTC
®
1446/LTC1446L are dual 12-bit digital-to-analog
converters (DACs) available in an SO-8 package. They are
complete with a rail-to-rail voltage output amplifier, an
internal reference and an easy-to-use 3-wire cascadable
serial interface.
The LTC1446 has an internal reference and a full-scale
output of 4.095V. It operates from a single 4.5V to 5.5V
supply.
The LTC1446L has an internal reference and a full-scale
output of 2.5V. It operates from a single 2.7V to 5.5V
supply.
The low power supply current makes the LTC1446 family
ideal for battery-powered applications. These DACs are
available in space saving 8-pin SO and PDIP packages and
require no external components for operation.
APPLICATIO S
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Digital Calibration
Industrial Process Control
Automatic Test Equipment
Cellular Telephones
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATION
Functional Block Diagram: Dual 12-Bit Rail-to-Rail DAC
7
V
CC
2 D
IN
LTC1446: 5V
LTC1446L: 3V TO 5V
+
12-BIT
DAC B
V
OUT B
8
1 CLK
3 CS/LD
24-BIT
SHIFT
REG
AND
DAC
LATCH
12-BIT
DAC A
4 D
OUT
POWER-ON
RESET
GND
6
1446/1446L TA01
DNL ERROR (LSB)
µP
–
RAIL-TO-RAIL
VOLTAGE
OUTPUT
+
–
V
OUT A
5
U
Differential Nonlinearity vs Input Code
0.5
0.4
0.3
0.2
0.1
0
–0.1
–0.2
–0.3
–0.4
–0.5
0
512 1024 1536 2048 2560 3072 3584 4095
CODE
1446/46L G13
U
U
1
LTC1446/LTC1446L
ABSOLUTE
AXI U
RATI GS
(Note 1)
V
OUT A
/V
OUT B
................................. –0.5V to V
CC
+ 0.5V
Maximum Junction Temperature .......................... 125°C
Storage Temperature Range ..................–65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
V
CC
to GND ................................................ –0.5 to 7.5V
Logic Inputs to GND ................................... –0.5 to 7.5V
Operating Temperature Range
LTC1446C/LTC1446LC ............................ 0°C to 70°C
LTC1446I/LTC1446LI ..........................–40°C to 85°C
PACKAGE/ORDER INFORMATION
TOP VIEW
CLK 1
D
IN
2
CS/LD 3
D
OUT
4
N8 PACKAGE
8-LEAD PDIP
8
7
6
5
V
OUT B
V
CC
GND
V
OUT A
ORDER PART
NUMBER
LTC1446CN8
LTC1446IN8
LTC1446LCN8
LTC1446LIN8
CLK 1
D
IN
2
CS/LD 3
D
OUT
4
T
JMAX
= 125°C,
θ
JA
= 100°C/W
Consult factory for Military grade parts.
The
q
denotes the specifications which apply over the full operating
temperature range. V
CC
= 4.5V to 5.5V (LTC1446), 2.7V to 5.5V (LTC1446L), V
OUT A
and V
OUT B
unloaded, T
A
= T
MIN
to T
MAX,
unless
otherwise noted.
SYMBOL
DAC
Resolution
DNL
INL
ZSE
V
OS
V
OS
TC
V
FS
Differential Nonlinearity
Integral Nonlinearity
Zero-Scale Error
Offset Error
Offset Error Tempco
Full-Scale Voltage
LTC1446, T
A
= 25°C
LTC1446
LTC1446L, T
A
= 25°C
LTC1446L
q
q
q
ELECTRICAL CHARACTERISTICS
PARAMETER
CONDITIONS
Guaranteed Monotonic (Note 2)
T
A
= 25°C
V
FS
TC
V
CC
I
CC
V
CC
I
CC
Full-Scale Voltage Tempco
Positive Supply Voltage
Supply Current
Positive Supply Voltage
Supply Current
For Specified Performance
4.5V
≤
V
CC
≤
5.5V (Note 5)
For Specified Performance
2.7V
≤
V
CC
≤
5.5V (Note 5)
q
q
Power Supply (LTC1446)
4.5
1000
2.7
650
5.5
1500
5.5
1000
V
µA
V
µA
Power Supply (LTC1446L)
q
q
2
U
U
W
W W
U
W
TOP VIEW
8
7
6
5
V
OUT B
V
CC
GND
V
OUT A
ORDER PART
NUMBER
LTC1446CS8
LTC1446IS8
LTC1446LCS8
LTC1446LIS8
S8 PART MARKING
1446
1446L
1446I 1446LI
S8 PACKAGE
8-LEAD PLASTIC SO
T
JMAX
= 125°C,
θ
JA
= 150°C/W
MIN
12
TYP
MAX
UNITS
Bits
q
q
q
q
±0.2
±2.0
±2.5
0
3
±2
±15
4.065
4.045
2.470
2.460
4.095
4.095
2.500
2.500
±0.1
±0.5
4.5
5.0
18
±18
4.125
4.145
2.530
2.540
LSB
LSB
LSB
mV
mV
µV/°C
V
V
V
V
LSB/°C
LTC1446/LTC1446L
ELECTRICAL CHARACTERISTICS
The
q
denotes the specifications which apply over the full operating temperature range. V
CC
= 4.5V to 5.5V (LTC1446), 2.7V to 5.5V
(LTC1446L), V
OUT A
and V
OUT B
unloaded, T
A
= T
MIN
to T
MAX,
unless otherwise noted.
SYMBOL
PARAMETER
Short-Circuit Current Low
Short-Circuit Current High
Output Impedance to GND
AC Performance
Voltage Output Slew Rate
Voltage Output Settling Time
(Note 3)
(Notes 3, 4) to
±0.5LSB
q
CONDITIONS
V
OUT
Shorted to GND
V
OUT
Shorted to V
CC
Input Code = 0
q
q
q
MIN
TYP
55
70
40
MAX
120
120
160
UNITS
mA
mA
Ω
V/µs
µs
Op Amp DC Performance
0.5
1
14
The
q
denotes the specifications which apply over the full operating temperature range.V
CC
= 5V (LTC1446), V
CC
= 3V (LTC1446L),
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
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
C
LOAD
= 15pF
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
LTC1446
TYP MAX
MIN
2
LTC1446L
TYP MAX
UNITS
V
0.8
V
CC
– 1.0
0.4
±10
10
40
0
40
40
50
40
20
150
20
30
60
0
60
60
80
60
30
V
CC
– 0.7
0.6
0.4
±10
10
V
V
V
µA
pF
ns
ns
ns
ns
ns
ns
ns
I
OUT
= – 1mA
I
OUT
= 1mA
V
IN
= GND to V
CC
Guaranteed by Design
q
q
q
q
220
ns
ns
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
Nonlinearity is defined from the first code that is greater than or
equal to the maximum offset specification to code 4095 (full scale).
Note 3:
Load is 5kΩ in parallel with 100pF.
Note 4:
DAC switched between all 1s and the code corresponding to V
OS
for the part.
Note 5:
Digital inputs at 0V or V
CC
.
3
LTC1446/LTC1446L
TYPICAL PERFORMANCE CHARACTERISTICS
LTC1446 Differential Nonlinearity
(DNL)
0.5
0.4
0.3
DNL ERROR (LSB)
INL ERROR (LSB)
2
1
0
–1
–2
–3
0
DNL ERROR (LSB)
512 1024 1536 2048 2560 3072 3584 4095
CODE
1446/46L G02
0.2
0.1
0
–0.1
–0.2
–0.3
–0.4
–0.5
0
512 1024 1536 2048 2560 3072 3584 4095
CODE
1446/46L G01
LTC1446L Integral Nonlinearity
3
2
INL ERROR (LSB)
V
CC
– V
OUT
(V)
1
0
–1
–2
–3
0
0.4
V
CC
– V
OUT
512 1024 1536 2048 2560 3072 3584 4095
CODE
1446/46L G04
LTC1446 Min Output Voltage vs
Output Sink Current
600
CODE: ALL 0'S
OUTPUT PULL-DOWN VOLTAGE (mV)
500
FULL-SCALE VOLTAGE (V)
400
125°C
300
–55°C
200
100
0
25°C
4.11
SUPPLY CURRENT (mA)
0
5
10
OUTPUT SINK CURRENT (mA)
LTC1446/46L • TPC07
4
U W
LTC1446 Integral Nonlinearity (INL)
3
LTC1446L Differential Nonlinearity
0.5
0.4
0.3
0.2
0.1
0
–0.1
–0.2
–0.3
–0.4
–0.5
0
512 1024 1536 2048 2560 3072 3584 4095
CODE
1446/46L G03
LTC1446 Min Supply Headroom for
Full Output Swing vs Load Current
0.8
∆V
OUT
< 1LSB
CODE: ALL 1's
V
OUT
= 4.095V
1.2
1.0
0.8
0.6
0.4
LTC1446L Min Supply Headroom for
Full Output Swing vs Load Current
∆V
OUT
< 1LSB
CODE: ALL 1's
V
OUT
= 2.5V
0.6
0.2
0.2
0
0
10
5
LOAD CURRENT (mA)
15
0
0
5
10
LOAD CURRENT (mA)
15
LTC1446/46L • TPC05
LTC1446/46L • TPC06
LTC1446 Full-Scale Voltage
vs Temperature
3.0
2.6
4.10
LTC1446 Supply Current
vs Logic Input Voltage
2.2
1.8
1.4
1.0
4.09
4.08
15
4.07
–55
–25
5
35
65
TEMPERATURE (°C)
95
125
0.6
0
1
2
3
4
LOGIC INPUT VOLTAGE (V)
5
1446/46L G09
1446/46L G09
LTC1446/LTC1446L
TYPICAL PERFORMANCE CHARACTERISTICS
LTC1446L Supply Current vs Logic
Input Voltage
1.2
1.1
SUPPLY CURRENT (mA)
970
960
SUPPLY CURRENT (µA)
SUPPLY CURRENT (µA)
1.0
0.9
0.8
0.7
0.6
0.5
0.5
1.0
1.5
2.0
LOGIC INPUT VOLTAGE (V)
1446/46L G10
PIN FUNCTIONS
CLK:
The Serial Interface Clock.
D
IN
:
The Serial Interface Data.
CS/LD:
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 registers,
updating the DAC outputs.
D
OUT
:
The output of the shift register which becomes valid
on the rising edge of the serial clock.
GND:
Ground.
V
OUT A
,V
OUT B
:
Buffered DAC Outputs.
V
CC
:
Positive Supply Input.
4.5V
≤
V
CC
≤
5.5V (LTC1446), 2.7V
≤
V
CC
≤
5.5V
(LTC1446L). Requires a 0.1µF bypass capacitor to
ground.
U W
2.5
LTC1446 Supply Current vs
Temperature
700
690
680
670
660
650
640
630
LTC1446L Supply Current
vs Temperature
950
940
930
920
910
V
CC
= 5.5V
V
CC
= 3.3V
V
CC
= 3V
V
CC
= 5V
V
CC
= 2.7V
V
CC
= 4.5V
5 25 45 65 85 105 125
TEMPERATURE (°C)
1446/46L G11
3.0
900
–55 –35 –15
620
– 55 – 35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
1446/46L G12
Large Signal Transient Response
V
OUT
(2V/DIV)
CS/LD
(5V/DIV)
TIME (10µs/DIV)
1446L G13
U
U
U
5
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