LTC1661
Micropower Dual
10-Bit DAC in MSOP
FEATURES
s
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DESCRIPTIO
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Tiny: Two 10-Bit DACs in an 8-Lead MSOP—
Half the Board Space of an SO-8
Micropower: 60µA per DAC
Sleep Mode: 1µA for Extended Battery Life
Rail-to-Rail Voltage Outputs Drive 1000pF
Wide 2.7V to 5.5V Supply Range
Double Buffered for Independent or Simultaneous
DAC Updates
Reference Range Includes Supply for Ratiometric
0V-to-V
CC
Output
Reference Input Has Constant Impedance over All
Codes (260kΩ Typ)—Eliminates External Buffers
3-Wire Serial Interface with
Schmitt Trigger Inputs
Differential Nonlinearity:
≤ ±0.75LSB
Max
The LTC
®
1661 integrates two accurate, serially addres-
sable, 10-bit digital-to-analog converters (DACs) in a
single tiny MS8 package. Each buffered DAC draws just
60µA total supply current, yet is capable of supplying DC
output currents in excess of 5mA and reliably driving
capacitive loads up to 1000pF. Sleep mode further re-
duces total supply current to a negligible 1µA.
Linear Technology’s proprietary, inherently monotonic
voltage interpolation architecture provides excellent lin-
earity while allowing for an exceptionally small external
form factor. The double-buffered input logic provides
simultaneous update capability and can be used to write to
either DAC without interrupting Sleep mode.
Ultralow supply current, power-saving Sleep mode and
extremely compact size make the LTC1661 ideal for
battery-powered applications, while its straightforward
usability, high performance and wide supply range make
it an excellent choice as a general purpose converter.
For additional outputs and even greater board density,
please refer to the LTC1660 micropower octal DAC for
10-bit applications. For 8-bit applications, please consult
the LTC1665 micropower octal DAC.
APPLICATIO S
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Mobile Communications
Digitally Controlled Amplifiers and Attenuators
Portable Battery-Powered Instruments
Automatic Calibration for Manufacturing
Remote Industrial Devices
, LTC and LT are registered trademarks of Linear Technology Corporation.
BLOCK DIAGRA
V
OUT A
8
GND
7
V
CC
6
V
OUT B
5
LATCH
LATCH
LATCH
LATCH
10-BIT
DAC A
10-BIT
DAC B
LSB
CONTROL
LOGIC
ADDRESS
DECODER
SHIFT REGISTER
1
CS/LD
2
SCK
3
D
IN
4
REF
1661 BD
U
Differential Nonlinearity (DNL)
0.75
0.60
0.40
0.20
0
–0.20
–0.40
–0.60
–0.75
0
256
512
CODE
768
1023
1661 G02
W
U
1
LTC1661
ABSOLUTE
(Note 1)
AXI U
RATI GS
Operating Temperature Range
LTC1661C ............................................. 0°C to 70°C
LTC1661I ........................................... – 40°C to 85°C
Lead Temperature (Soldering, 10 sec)................ 300°C
V
CC
to GND .............................................. – 0.3V to 7.5V
Logic Inputs to GND ................................ – 0.3V to 7.5V
V
OUT A
, V
OUT B
, REF to GND ............ – 0.3V to V
CC
+ 0.3V
Maximum Junction Temperature ......................... 125°C
Storage Temperature Range ................ – 65°C to 150°C
PACKAGE/ORDER I FOR ATIO
TOP VIEW
CS/LD
SCK
D
IN
REF
1
2
3
4
8
7
6
5
V
OUT A
GND
V
CC
V
OUT B
ORDER PART
NUMBER
CS/LD 1
LTC1661CMS8
LTC1661IMS8
MS8 PART MARKING
LTDV
LTDW
MS8 PACKAGE
8-LEAD PLASTIC MSOP
T
JMAX
= 125°C,
θ
JA
= 150°C/W
Consult factory for Military grade parts.
The
q
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 2.7V to 5.5V, V
REF
≤
V
CC
, V
OUT
Unloaded unless otherwise noted.
SYMBOL
Accuracy
Resolution
Monotonicity
DNL
INL
V
OS
FSE
PSR
Differential Nonlinearity
Integral Nonlinearity
Offset Error
V
OS
Temperature Coefficient
Full-Scale Error
Full-Scale Error Temperature Coefficient
Power Supply Rejection
Input Voltage Range
Resistance
Capacitance
I
REF
V
CC
I
CC
Reference Current
Positive Supply Voltage
Supply Current
Sleep Mode
For Specified Performance
V
CC
= 5V (Note 3)
V
CC
= 3V (Note 3)
Sleep Mode (Note 3)
Power Supply
q
q
q
q
q
ELECTRICAL CHARACTERISTICS
PARAMETER
CONDITIONS
1V
≤
V
REF
≤
V
CC
– 0.1V (Note 2)
1V
≤
V
REF
≤
V
CC
– 0.1V (Note 2)
1V
≤
V
REF
≤
V
CC
– 0.1V (Note 2)
Measured at Code 20
V
CC
= 5V, V
REF
= 4.096V
V
REF
= 2.5V
Reference Input
q
Active Mode
2
U
U
W
W W
U
W
TOP VIEW
8
7
6
5
V
OUT A
GND
V
CC
V
OUT B
ORDER PART
NUMBER
LTC1661CN8
LTC1661IN8
SCK 2
D
IN
3
REF 4
N8 PACKAGE
8-LEAD PLASTIC DIP
T
JMAX
= 125°C,
θ
JA
= 100°C/W
MIN
10
10
TYP
MAX
UNITS
Bits
Bits
q
q
q
q
±0.1
±0.4
±5
±15
±1
±30
0.18
0
140
260
15
0.001
2.7
120
95
1
±0.75
±2
±30
±12
LSB
LSB
mV
µV/°C
LSB
µV/°C
LSB/V
q
V
CC
V
kΩ
pF
q
q
q
1
5.5
195
154
3
µA
V
µA
µA
µA
LTC1661
The
q
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 2.7V to 5.5V, V
REF
≤
V
CC
, V
OUT
Unloaded unless otherwise noted.
SYMBOL
PARAMETER
Short-Circuit Current Low
Short-Circuit Current High
AC Performance
Voltage Output Slew Rate
Voltage Output Settling Time
Capacitive Load Driving
Digital I/O
V
IH
V
IL
I
LK
C
IN
Digital Input High Voltage
Digital Input Low Voltage
Digital Input Leakage
Digital Input Capacitance
V
CC
= 2.7V to 5.5V
V
CC
= 2.7V to 3.6V
V
CC
= 4.5V to 5.5V
V
CC
= 2.7V to 5.5V
V
IN
= GND to V
CC
(Note 6)
q
q
q
q
q
q
ELECTRICAL CHARACTERISTICS
CONDITIONS
V
OUT
= 0V, V
CC
= V
REF
= 5V, Code = 1023
V
OUT
= V
CC
= V
REF
= 5V, Code = 0
Rising (Notes 4, 5)
Falling (Notes 4, 5)
To
±0.5LSB
(Notes 4, 5)
q
q
MIN
10
7
TYP
25
19
0.60
0.25
30
1000
MAX
100
120
UNITS
mA
mA
V/µs
V/µs
µs
pF
V
V
DC Performance
2.4
2.0
0.8
0.6
±10
10
V
V
µA
pF
TI I G CHARACTERISTICS
range, otherwise specifications are at T
A
= 25°C.
PARAMETER
D
IN
Valid to SCK Setup
D
IN
Valid to SCK Hold
SCK High Time
SCK Low Time
CS/LD Pulse Width
LSB SCK High to CS/LD High
CS/LD Low to SCK High
SCK Low to CS/LD Low
CS/LD High to SCK Positive Edge
SCK Frequency
V
CC
= 2.7V to 5.5V
t
1
t
2
t
3
t
4
t
5
t
6
t
7
t
9
t
11
D
IN
Valid to SCK Setup
D
IN
Valid to SCK Hold
SCK High Time
SCK Low Time
CS/LD Pulse Width
LSB SCK High to CS/LD High
CS/LD Low to SCK High
SCK Low to CS/LD Low
CS/LD High to SCK Positive Edge
SCK Frequency
SYMBOL
t
1
t
2
t
3
t
4
t
5
t
6
t
7
t
9
t
11
V
CC
= 4.5V to 5.5V
Note 1:
Absolute maximum ratings are those values beyond which the life
of a device may be impaired.
UW
The
q
denotes the specifications which apply over the full operating temperature
CONDITIONS
q
q
MIN
40
0
30
30
80
30
20
0
20
TYP
15
– 10
14
14
27
2
– 21
–5
0
MAX
UNITS
ns
ns
ns
ns
ns
ns
ns
ns
ns
(Note 6)
(Note 6)
(Note 6)
(Note 6)
(Note 6)
(Note 6)
(Note 6)
Square Wave (Note 6)
(Note 6)
(Note 6)
(Note 6)
(Note 6)
(Note 6)
(Note 6)
(Note 6)
(Note 6)
(Note 6)
Square Wave (Note 6)
q
q
q
q
q
q
q
q
16.7
60
0
50
50
100
50
30
0
30
20
– 10
15
15
30
3
– 14
–5
0
10
MHz
ns
ns
ns
ns
ns
ns
ns
ns
ns
MHz
q
q
q
q
q
q
q
q
q
q
Note 2:
Nonlinearity and monotonicity are defined from code 20 to code
1023 (full scale). See Applications Information.
3
LTC1661
TI I G CHARACTERISTICS
Note 3:
Digital inputs at 0V or V
CC
.
Note 4:
Load is 10kΩ in parallel with 100pF.
Note 5:
V
CC
= V
REF
= 5V. DAC switched between 0.1V
FS
and 0.9V
FS
,
i.e., codes k = 102 and k = 922.
Note 6:
Guaranteed by design and not subject to test.
TYPICAL PERFOR A CE CHARACTERISTICS
Integral Nonlinearity (INL)
2.0
1.5
1.0
0.5
LSB
0.20
V
CC
– V
OUT
(mV)
LSB
0
–0.5
–1.0
–1.5
–2.0
0
256
512
CODE
768
1023
1661 G01
Minimum V
OUT
vs
Load Current (Output Sinking)
1400
1200
1000
V
OUT
(mV)
V
CC
= 5V
CODE = 0
V
OUT
(V)
V
OUT
(V)
800
25°C
600
–55°C
400
200
0
0
2
|
I
OUT
|
(mA) (Sinking)
4
6
4
U W
UW
Differential Nonlinearity (DNL)
0.75
0.60
0.40
1000
800
600
1400
1200
Minimum Supply Headroom vs
Load Current (Output Sourcing)
V
REF
= 4.096V
∆V
OUT
< 1LSB
CODE = 1023
125°C
25°C
–55°C
400
0
–0.20
–0.40
–0.60
–0.75
0
256
512
CODE
768
1023
1661 G02
200
0
0
2
|
4
6
I
OUT
(mA) (Sourcing)
|
8
10
1661 G03
Midscale Output Voltage vs
Load Current
3
2.9
2.8
2.7
2.6
2.5
2.4
2.3
2.2
2.1
2
SOURCE
–20
–10
SINK
20
30
1661 G05
Midscale Output Voltage vs
Load Current
2
1.9
1.8
1.7
1.6
1.5
1.4
1.3
1.2
1.1
1
–15 –12
–8
SOURCE
SINK
8
12 15
1661 G06
125°C
V
REF
= V
CC
CODE = 512
V
CC
= 5.5V
V
REF
= V
CC
CODE = 512
V
CC
= 3.6V
V
CC
= 3V
V
CC
= 5V
V
CC
= 4.5V
V
CC
= 2.7V
8
10
1661 G04
–30
0
10
I
OUT
(mA)
–4
0
4
I
OUT
(mA)
LTC1661
TYPICAL PERFOR A CE CHARACTERISTICS
Load Regulation vs
Output Current
2
1.5
1
∆V
OUT
(LSB)
V
CC
= V
REF
= 5V
CODE = 512
∆V
OUT
(LSB)
0
–0.5
–1
–1.5
–2
–2
SOURCE
–1
0
I
OUT
(mA)
SINK
1
2
1661 G07
0
–0.5
–1
–1.5
–2
–500
SOURCE
0
I
OUT
(µA)
SINK
V
OUT
(V)
0.5
Supply Current vs
Logic Input Voltage
1.0
ALL DIGITAL INPUTS
SHORTED TOGETHER
0.8
SUPPLY CURRENT (mA)
SUPPLY CURRENT (µA)
0.6
0.4
0.2
0
0
1
2
3
4
LOGIC INPUT VOLTAGE (V)
5
1661 G10
TI I G DIAGRA
SCK
t
9
D
IN
t
5
CS/LD
U W
W
t
7
Load Regulation vs
Output Current
5
2
1.5
1
0.5
V
CC
= V
REF
= 3V
CODE = 512
Large-Signal Step Response
V
CC
= V
REF
= 5V
10% TO
CODE = 922
90% STEP
4
3
2
1
CODE = 102
0
20
40
60
TIME (µs)
80
100
1661 G09
0
500
1661 G08
Supply Current vs Temperature
150
140
130
120
110
100
90
80
70
60
50
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
1661 G11
V
REF
= V
CC
CODE = 1023
V
CC
= 5.5V
V
CC
= 4.5V
V
CC
= 3.6V
V
CC
= 2.7V
UW
t
1
t
2
t
3
t
4
t
6
t
11
A3
A2
A1
X1
X0
1661 TD
5
嵌入式系统
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