LTC1657LIGN#TR [Linear]
LTC1657 - Parallel 16-Bit Rail-to-Rail Micropower DAC; Package: SSOP; Pins: 28; Temperature Range: -40°C to 85°C;
| 型号： | LTC1657LIGN#TR |
| 厂家： | 
Linear |
| 描述： | LTC1657 - Parallel 16-Bit Rail-to-Rail Micropower DAC; Package: SSOP; Pins: 28; Temperature Range: -40°C to 85°C |
| 文件： | 总16页 (文件大小：166K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LTC1655/LTC1655L
16-Bit Rail-to-Rail
Micropower DACs in
SO-8 Package
U
DESCRIPTIO
FEATURES
The LTC®1655/LTC1655L are rail-to-rail voltage output,
16-bit digital-to-analog converters in an SO-8 package.
They include an output buffer and a reference. The 3-wire
serial interface is compatible with SPI/QSPI and
MICROWIRETM protocols. The CLK input has a Schmitt
trigger that allows direct optocoupler interface.
■
16-Bit Monotonicity Over Temperature
■
Deglitched Rail-to-Rail Voltage Output
■
SO-8 Package
ICC(TYP): 600µA
Internal Reference: 2.048V (LTC1655)
■
■
1.25V (LTC1655L)
■
Maximum DNL Error: ±1LSB
TheLTC1655hasanonboard2.048Vreferencethatcanbe
overdriven to a higher voltage. The output swings from 0V
to 4.096V when using the internal reference. The typical
power dissipation is 3.0mW on a single 5V supply.
■
Settling Time: 20µS to ±1LSB
■
750kHz Max Update Rate
Power-On Reset to Zero Volts
3-Wire Cascadable Serial Interface
Low Cost
Pin Compatible Upgrade for LTC1451 12-Bit DAC
Family
■
■
TheLTC1655Lhasanonboard1.25Vreferencethatcanbe
overdriven to a higher voltage. The output swings from 0V
to 2.5V when using the internal reference. The typical
power dissipation is 1.8mW on a single 3V supply.
■
■
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The LTC1655/LTC1655L are pin compatible with Linear
Technology’s 12-bit VOUT DAC family, allowing an easy
upgrade path. They are the only buffered 16-bit DACs in
an SO-8 package and they include an onboard reference
for standalone performance.
APPLICATIO S
■
Digital Calibration
■
Industrial Process Control
■
Automatic Test Equipment
Cellular Telephones
■
, LTC and LT are registered trademarks of Linear Technology Corporation.
MICROWIRE is a trademark of National Semiconductor Corporation.
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FU CTIO AL BLOCK DIAGRA
Functional Block Diagram: 16-Bit Rail-to-Rail DAC
Differential Nonlinearity
vs Input Code
LTC1655: 4.5V TO 5.5V
LTC1655L: 2.7V TO 5.5V
LTC1655: 2.048V
LTC1655L: 1.25V
1.0
0.8
8
6
V
CC
REF
0.6
REF
2
1
D
IN
0.4
CLK
16-BIT
SHIFT
REG
0.2
16
µP
16-BIT
DAC
0
+
–
3
CS/LD
V
OUT
7
AND
–0.2
–0.4
–0.6
–0.8
–1.0
DAC
LATCH
4
D
OUT
POWER-ON
RESET
TO
OTHER
DACS
0
16384
32768
CODE
49152
65535
GND
5
1655/55L TA01
1655/55L TA02
1
LTC1655/LTC1655L
W W
U W
W
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/O
ABSOLUTE MAXIMUM RATINGS
PACKAGE RDER I FOR ATIO
(Note 1)
ORDER PART
NUMBER
VCC to GND .............................................. –0.5V to 7.5V
TTL Input Voltage .................................... –0.5V to 7.5V
VOUT, REF ....................................... –0.5V to VCC + 0.5V
Maximum Junction Temperature ......................... 125°C
Operating Temperature Range
LTC1655C/LTC1655LC ........................... 0°C to 70°C
LTC1655I/LTC1655LI ........................ –40°C to 85°C
Storage Temperature Range ................ –65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
TOP VIEW
LTC1655CN8
CLK
1
2
3
4
8
7
6
5
V
V
CC
LTC1655IN8
LTC1655CS8
LTC1655IS8
LTC1655LCN8
LTC1655LIN8
LTC1655LCS8
LTC1655LIS8
D
IN
OUT
CS/LD
REF
D
GND
OUT
N8 PACKAGE
8-LEAD PDIP
S8 PACKAGE
8-LEAD PLASTIC SO
TJMAX = 125°C, θJA = 100°C/W (N8)
JMAX = 125°C, θJA = 150°C/W (S8)
T
S8 PART MARKING
1655
1655I
1655L
1655LI
Consult factory for Military grade parts.
ELECTRICAL CHARACTERISTICS
The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C.
VCC = 4.5V to 5.5V (LTC1655), VCC = 2.7V to 5.5V (LTC1655L); VOUT unloaded, REF unloaded, unless otherwise noted.
SYMBOL PARAMETER
DAC
CONDITIONS
MIN
TYP
MAX
UNITS
Resolution
●
●
16
16
Bits
Bits
Monotonicity
DNL
Differential Nonlinearity
Guaranteed Monotonic (Note 2)
LTC1655, REF = 2.2V, V = 5V (Note 8) (External)
●
●
±0.3
±0.5
±1.0
±1.0
LSB
LSB
CC
LTC1655L, REF = 2.2V, V = 5V (Note 8) (External)
CC
INL
Integral Nonlinearity
Zero Scale Error
Offset Error
LTC1655, REF = 2.2V, V = 5V (Note 8) (External)
●
●
±8
±8
±20
±20
LSB
LSB
CC
LTC1655L, REF = 2.2V, V = 5V (Note 8) (External)
CC
ZSE
LTC1655
LTC1655L
●
●
0
0
3.0
3.5
mV
mV
V
V
Measured at Code 200
OS
LTC1655, REF = 2.2V, V = 5V (Note 8) (External)
●
●
±0.5
±0.5
±3.0
±3.5
mV
mV
CC
LTC1655L, REF = 1.3V, V = 2.7V (Note 8) (External)
CC
TC
Offset Error Tempco
Gain Error
±5
±5
0.5
µV/°C
LSB
OS
REF = 2.2V (External), V = 5V (Note 8)
●
±16
CC
Gain Error Drift
ppm/°C
Power Supply
V
Positive Supply Voltage
For Specified Performance
LTC1655
LTC1655L
CC
●
●
4.5
2.7
5.5
5.5
V
V
I
Supply Current
(Note 3)
●
600
1200
µA
CC
2
LTC1655/LTC1655L
ELECTRICAL CHARACTERISTICS
The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C.
CC = 4.5V to 5.5V (LTC1655), VCC = 2.7V to 5.5V (LTC1655L); VOUT unloaded, REF unloaded, unless otherwise noted.
V
SYMBOL PARAMETER
Op Amp DC Performance
CONDITIONS
MIN
TYP
MAX
UNITS
Short-Circuit Current Low
V
Shorted to GND
OUT
LTC1655
LTC1655L
●
●
70
70
120
140
mA
mA
Short-Circuit Current High
Output Impedance to GND
Output Line Regulation
V
Shorted to V
OUT CC
LTC1655
LTC1655L
●
●
80
70
140
150
mA
mA
Input Code = 0
LTC1655
LTC1655L
●
●
40
70
120
160
Ω
Ω
Input Code = 65535, with Internal Reference
±3
mV/V
AC Performance
Voltage Output Slew Rate
(Note 4)
●
±0.3
±0.7
V/µs
Voltage Output Settling Time
(Note 4) to 0.0015% (16-Bit Settling Time), V = 5V
20
10
µs
µs
CC
(Note 4) to 0.012% (13-Bit Settling Time), V = 5V
CC
Digital Feedthrough
(Note 5)
0.3
12
nV-s
nV-s
Midscale Glitch Impulse
DAC Switched Between 8000 and 7FFF
H
H
Output Voltage Noise
Spectral Density
LTC1655, At 1kHz
LTC1655L, At 1kHz
280
220
nV√Hz
nV√Hz
Reference Output
Reference Output Voltage
LTC1655
LTC1655L
●
●
2.036
1.240
2.048
1.250
2.060
1.260
V
V
Reference Input Range
(Notes 6, 7) LTC1655
LTC1655L
2.2
1.3
V
CC
V
CC
/2
/2
V
V
Reference Output Tempco
Reference Input Resistance
LTC1655
LTC1655L
5
10
ppm/°C
ppm/°C
LTC1655, REF Overdriven to 2.2V
LTC1655L, REF Overdriven to 1.3V
●
●
8.5
7.0
13
13
kΩ
kΩ
Reference Short-Circuit Current
Reference Output Line Regulation
Reference Load Regulation
●
40
100
±1.5
5
mA
mV/V
mV/A
I
= 100µA
●
OUT
Reference Output Voltage Noise
Spectral Density
LTC1655, At 1kHz
LTC1655L, At 1kHz
150
115
nV√Hz
nV√Hz
Digital I/O
V
V
V
V
Digital Input High Voltage
Digital Input Low Voltage
Digital Output High Voltage
Digital Output Low Voltage
LTC1655
LTC1655L
●
●
2.4
2.0
V
V
IH
LTC1655
LTC1655L
●
●
0.8
0.6
V
V
IL
LTC1655, I
LTC1655L, I
= –1mA
●
●
V
V
– 1.0
V
V
OH
OL
OUT
CC
CC
= –1mA
– 0.7
OUT
LTC1655, I
LTC1655L, I
= 1mA
●
●
0.4
0.4
V
V
OUT
= 1mA
OUT
3
LTC1655/LTC1655L
ELECTRICAL CHARACTERISTICS
The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C.
VCC = 4.5V to 5.5V (LTC1655), VCC = 2.7V to 5.5V (LTC1655L); VOUT unloaded, REF unloaded, unless otherwise noted.
SYMBOL PARAMETER
CONDITIONS
= GND to V
CC
MIN
TYP
MAX
±10
10
UNITS
µA
I
Digital Input Leakage
V
●
LEAK
IN
C
Digital Input Capacitance
(Note 7)
pF
IN
Switching
t
t
t
t
t
t
t
t
t
D
D
Valid to CLK Setup
Valid to CLK Hold
LTC1655
LTC1655L
●
●
40
60
ns
ns
1
2
3
4
5
6
7
8
9
IN
LTC1655
LTC1655L
●
●
0
0
ns
ns
IN
CLK High Time
LTC1655
LTC1655L
●
●
40
60
ns
ns
CLK Low Time
LTC1655
LTC1655L
●
●
40
60
ns
ns
CS/LD Pulse Width
LSB CLK to CS/LD
CS/LD Low to CLK
LTC1655
LTC1655L
●
●
50
80
ns
ns
LTC1655
LTC1655L
●
●
40
60
ns
ns
LTC1655
LTC1655L
●
●
20
30
ns
ns
D
OUT
Output Delay
LTC1655, C
LTC1655L, C
= 15pF
LOAD
●
●
20
20
120
300
ns
ns
= 15pF
LOAD
CLK Low to CS/LD Low
LTC1655
LTC1655L
●
●
20
30
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 code 128 to code 65535 (full scale).
See Applications Information.
Note 5: Part is clocked with pin toggling between 1s and 0s, CS/LD is low.
Note 6: Reference can be overdriven (see Applications Information).
Note 7: Guaranteed by design. Not subject to test.
Note 8: Guaranteed by correlation for other reference and supply
conditions.
Note 3: DAC switched between all 1s and all 0s. V = 4.096V.
FS
Note 4: Digital inputs at 0V or V
.
CC
4
LTC1655/LTC1655L
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TYPICAL PERFORMANCE CHARACTERISTICS
VCC = 5V (LTC1655), VCC = 3V (LTC1655L) unless otherwise noted.
TC1655 Differential Nonlinearity
LTC1655L Differential Nonlinearity
1.0
0.8
1.0
0.8
0.6
0.6
0.4
0.4
0.2
0.2
0
0
–0.2
–0.4
–0.6
–0.8
–1.0
–0.2
–0.4
–0.6
–0.8
–1.0
0
16,384
32,768
49,152
65,535
65,535
15
0
16,384
32,768
49,152
65,535
DIGITAL INPUT CODE
DIGITAL INPUT CODE
1655/55L G01
1655/55L G01a
LTC1655 Integral Nonlinearity
LTC1655L Integral Nonlinearity
10
8
10
8
6
6
4
4
2
2
0
0
–2
–4
–6
–8
–10
–2
–4
–6
–8
–10
128
16,480
32,832
49,184
65,535
0
16,384
32,768
49,152
DIGITAL INPUT CODE
DIGITAL INPUT CODE
1655/55L G02a
1655/55L G02
LTC1655 Minimum Supply
Headroom for Full Output Swing
vs Load Current
LTC1655L Minimum Supply
Headroom for Full Output Swing
vs Load Current
1.2
1.0
0.8
0.6
0.4
0.2
0
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
∆V
OUT
< 1LSB
∆V
OUT
< 1LSB
OUT
OUT
V
= 4.096V
V
= 2.5V
CODE: ALL 1’s
CODE: ALL 1’s
125°C
25°C
125°C
25°C
–55°C
–55°C
10
5
LOAD CURRENT (mA)
15
10
5
LOAD CURRENT (mA)
0
0
1655/55L G03a
1655/55L G03
5
LTC1655/LTC1655L
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TYPICAL PERFORMANCE CHARACTERISTICS
VCC = 5V (LTC1655), VCC = 3V (LTC1655L) unless otherwise noted.
LTC1655 Minimum Output Voltage
vs Output Sink Current
LTC1655L Minimum Output
Voltage vs Output Sink Current
1.0
0.8
0.6
0.4
0.2
0
CODE: ALL 0s
CODE: ALL 0s
0.8
125°C
25°C
–55°C
0.6
125°C
0.4
25°C
–55°C
0.2
0
10
OUTPUT SINK CURRENT (mA)
15
10
15
0
0
5
5
OUTPUT SINK CURRENT (mA)
1655/55L G04
1655/55L G04a
LTC1655L Full-Scale Voltage vs
Temperature
LTC1655 Full-Scale Voltage vs
Temperature
4.10
4.09
4.08
4.07
2.510
2.505
2.500
2.495
2.490
–55
5
35
65
95
125
–55
5
35
65
95
125
–25
–25
TEMPERATURE (°C)
TEMPERATURE (°C)
1655/55L G05
1655/55L G05a
LTC1655 Offset vs Temperature
LTC1655L Offset vs Temperature
1.0
0.8
0.6
0.5
0.4
0.3
0.2
0.1
0
0.6
0.4
0.2
0
–0.2
–0.4
–0.6
–0.8
–1.0
–55
–10
35
80
125
–55
–10
35
80
125
TEMPERATURE (°C)
TEMPERATURE (°C)
1655/55L G06
1655/55L G06a
6
LTC1655/LTC1655L
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TYPICAL PERFORMANCE CHARACTERISTICS
VCC = 5V (LTC1655), VCC = 3V (LTC1655L) unless otherwise noted.
LTC1655 Supply Current vs
Logic Input Voltage
LTC1655L Supply Current vs
Logic Input Voltage
1.0
0.8
0.6
0.4
3.0
2.6
2.2
1.8
1.4
1.0
0.6
0
1
2
3
0
1
2
3
4
5
LOGIC INPUT VOLTAGE (V)
LOGIC INPUT VOLTAGE (V)
1655/55L G07a
1655/55L G07
LTC1655 Supply Current vs
Temperature
LTC1655L Supply Current vs
Temperature
700
680
660
640
620
600
580
580
560
540
520
500
480
460
V
CC
= 5.5V
V
CC
= 3.3V
V
CC
= 5V
V
V
= 3V
CC
V
CC
= 4.5V
= 2.7V
CC
–55 –35 –15
5
25 45 65 85 105 125
–55 –35 –15
5
25 45 65 85 105 125
TEMPERATURE (°C)
TEMPERATURE (°C)
1655/55L G08
1655/55L G08a
LTC1655 Large-Signal Transient
Response
LTC1655L Large-Signal Transient
Response
5
4
3
2
1
0
3
2
1
0
V
A
UNLOADED
V
UNLOADED
OUT
OUT
T
= 25°C
T = 25°C
A
TIME (5µs/DIV)
TIME (5µs/DIV)
1655/55L G09
1655/55L G10
7
LTC1655/LTC1655L
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PIN FUNCTIONS
CLK (Pin 1): The TTL Level Input for the Serial Interface
Clock.
GND (Pin 5): Ground.
REF (Pin 6): Reference. Output of the internal reference is
2.048V (LTC1655), 1.25V (LTC1655L). There is a gain of
two from this pin to the output. The reference can be
overdriven from 2.2V to VCC/2 (LTC1655) and 1.3V to
VCC/2 (LTC1655L). When tied to VCC/2, the output will
swing from GND to VCC. The output can only swing to
within its offset specification of VCC (see Applications
Information).
DIN (Pin 2): The TTL Level Input for the Serial Interface
Data. Data on the DIN pin is latched into the shift register
on the rising edge of the serial clock and is loaded MSB
first. The LTC1655/LTC1655L requires a 16-bit word.
CS/LD (Pin 3): The TTL Level Input for the Serial Inter-
face 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.
VOUT (Pin7):DeglitchedRail-to-RailVoltageOutput. VOUT
clears to 0V on power-up.
DOUT (Pin 4): Output of the Shift Register. Becomes valid
on the rising edge of the serial clock and swings from GND
to VCC.
VCC (Pin 8): Positive Supply Input. 4.5V ≤ VCC ≤ 5.5V
(LTC1655), 2.7V ≤ VCC ≤ 5.5V (LTC1655L). Requires a
0.1µF bypass capacitor to ground.
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TI I G DIAGRA
t
t
1
9
t
t
6
t
t
3
t
2
4
7
CLK
1
2
3
15
16
D15
MSB
D0
LSB
D
D14
D13
D1
IN
t
5
CS/LD
t
8
D15
PREVIOUS WORD
D14
D13
D0
PREVIOUS WORD
D15
D
OUT
PREVIOUS WORD PREVIOUS WORD
CURRENT WORD
1655/55L TD
8
LTC1655/LTC1655L
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DEFI ITIO S
Differential Nonlinearity (DNL): The difference between
the measured change and the ideal 1LSB change for any
twoadjacentcodes. TheDNLerrorbetweenanytwocodes
is calculated as follows:
lowestcodethatguaranteestheoutputwillbegreaterthan
zero. The INL error at a given input code is calculated as
follows:
INL = [VOUT – VOS – (VFS – VOS)(code/65535)]/LSB
DNL = (∆VOUT – LSB)/LSB
Where VOUT is the output voltage of the DAC measured at
the given input code.
Where ∆VOUT is the measured voltage difference between
two adjacent codes.
Least Significant Bit (LSB): The ideal voltage difference
between two successive codes.
DigitalFeedthrough: Theglitchthatappearsattheanalog
outputcausedbyACcouplingfromthedigitalinputswhen
they change state. The area of the glitch is specified in
(nV)(sec).
LSB = 2VREF/65536
Resolution (n): Defines the number of DAC output states
(2n) that divide the full-scale range. Resolution does not
imply linearity.
Full-Scale Error (FSE): The deviation of the actual full-
scale voltage from ideal. FSE includes the effects of offset
and gain errors (see Applications Information).
Voltage Offset Error (VOS): Nominally, the voltage at the
output when the DAC is loaded with all zeros. A single
supply DAC can have a true negative offset, but the output
cannot go below zero (see Applications Information).
Gain Error (GE): The difference between the full-scale
output of a DAC from its ideal full-scale value after offset
error has been adjusted.
For this reason, single supply DAC offset is measured at
the lowest code that guarantees the output will be greater
than zero.
Integral Nonlinearity (INL): The deviation from a straight
line passing through the endpoints of the DAC transfer
curve(EndpointINL).Becausetheoutputcannotgobelow
zero, the linearity is measured between full scale and the
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OPERATIO
Serial Interface
of the chips, then the CS/LD signal is pulled high to update
all of them simultaneously. The shift register and DAC
register are cleared to all 0s on power-up.
The data on the DIN input is loaded into the shift register
ontherisingedgeoftheclock.TheMSBisloadedfirst.The
DAC register loads the data from the shift register when
CS/LD is pulled high. The clock is disabled internally when
CS/LD is high. Note: CLK must be low before CS/LD is
pulled low to avoid an extra internal clock pulse. The input
word must be 16 bits wide.
Voltage Output
The LTC1655/LTC1655L rail-to-rail buffered output can
source or sink 5mA over the entire operating temperature
range while pulling to within 600mV of the positive supply
voltage or ground. The output stage is equipped with a
deglitcherthatgivesamidscaleglitchof12nV-s.Atpower-
up, the output clears to 0V.
The buffered output of the 16-bit shift register is available
on the DOUT pin which swings from GND to VCC.
Multiple LTC1655s/LTC1655Ls may be daisy-chained to-
getherbyconnectingtheDOUT pintotheDIN pinofthenext
chip while the clock and CS/LD signals remain common to
all chips in the daisy chain. The serial data is clocked to all
The output swings to within a few millivolts of either sup-
ply rail when unloaded and has an equivalent output resis-
tance of 40Ω (70Ω for the LTC1655L) when driving a load
totherails.Theoutputcandrive1000pFwithoutgoinginto
oscillation.
9
LTC1655/LTC1655L
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APPLICATIONS INFORMATION
Rail-to-Rail Output Considerations
error (FSE) is positive, the output for the highest codes
limits at VCC as shown in Figure 1c. No full-scale limiting
can occur if VREF is less than (VCC – FSE)/2.
In any rail-to-rail DAC, the output swing is limited to
voltages within the supply range.
Offset and linearity are defined and tested over the region
of the DAC transfer function where no output limiting can
occur.
If the DAC offset is negative, the output for the lowest
codes limits at 0V as shown in Figure 1b.
Similarly, limiting can occur near full-scale when the REF
pin is tied to VCC/2. If VREF = VCC/2 and the DAC full-scale
POSITIVE
FSE
V
CC
V
= V /2
CC
OUTPUT
VOLTAGE
REF
INPUT CODE
(1c)
V
CC
V
= V /2
CC
OUTPUT
VOLTAGE
REF
0
32768
65535
INPUT CODE
(1a)
OUTPUT
VOLTAGE
0V
NEGATIVE
OFFSET
INPUT CODE
1655/55L F01
(1b)
Figure 1. Effects of Rail-to-Rail Operation On a DAC Transfer Curve. (a) Overall Transfer Function (b) Effect of Negative
Offset for Codes Near Zero Scale (c) Effect of Positive Full-Scale Error for Input Codes Near Full Scale When VREF = VCC/2
10
LTC1655/LTC1655L
U
TYPICAL APPLICATIONS
This circuit shows how to use an LTC1655 to make an is used for the digitally controlled 0mA to 16mA current.
optoisolated digitally controlled 4mA to 20mA process RS is a sense resistor and the op amp modulates the
controller. The controller circuitry, including the transistor Q1 to provide the 4mA to 20mA current through
optoisolation, ispoweredbytheloopvoltagethatcanhave this resistor. The potentiometers allow for offset and full-
a wide range of 6V to 30V. The 2.048V reference output of scale adjustment. The control circuitry dissipates well
the LTC1655 is used for the 4mA offset current and VOUT under the 4mA budget at zero scale.
An Isolated 4mA to 20mA Process Controller
V
LOOP
6V TO 30V
150k
1%
LT®1121-5
IN OUT
20k
5k
8
6
1µF
V
V
REF
CC
1
2
3
75k
1%
CLK
FROM
7
3
2
7
V
OUT
LTC1655
D
IN
+
OPTOISOLATED
INPUTS
1k
6
Q1
2N3440
LT®1077
CS/LD
GND
3k
–
4
5
R
S
5V
10Ω
OPTOISOLATORS
I
OUT
10k
CLK
IN
1655/55L TA03
D
CS/LD
CLK
IN
CS/LD
500Ω
4N28
D
11
LTC1655/LTC1655L
U
TYPICAL APPLICATIONS
the onboard reference is always sourcing current and
never has to sink any current even when VOUT is at full
scale. The LT1077 output will have a wide bipolar output
swing of –4.096V to 4.096V as shown in the figure below.
With this output swing 1LSB = 125µV.
This circuit shows how to make a bipolar output 16-bit
DAC with a wide output swing using an LTC1655 and an
LT1077. R1 and R2 resistively divide down the LTC1655
output and an offset is summed in using the LTC1655
onboard2.048VreferenceandR3andR4. R5ensuresthat
A Wide Swing, Bipolar Output 16-Bit DAC
5V
0.1µF
8
V
CC
1
2
3
CLK
7
µP
V
OUT
LTC1655
D
IN
R1
5V
CS/LD
100k
GND
5
V
REF
6
1%
3
2
7
LT1077
4
+
–
6
(2)(D )(4.096)
IN
R2
200k
1%
V
OUT
:
– 4.096V
TRANSFER CURVE
32768
65536
4.096
R3
100k
1%
R4
200k
1%
–5V
65535
0
1655/55L TA05
V
OUT
D
IN
R5
100k
1%
–4.096
12
LTC1655/LTC1655L
U
TYPICAL APPLICATIONS
Thiscircuitshowsadigitallyprogrammablecurrentsource
fromanexternalvoltagesourceusinganexternalopamp,
an LT1218 and an NPN transistor (2N3440). Any digital
word from 0 to 65535 is loaded into the LTC1655 and its
output correspondingly swings from 0V to 4.096V. This
voltage will be forced across the resistor RA. If RA is
chosen to be 412Ω, the output current will range from
0mA at zero scale to 10mA at full scale. The minimum
voltage for VS is determined by the load resistor RL and
Q1’s VCESAT voltage. With a load resistor of 50Ω, the
voltage source can be 5V.
Digitally Programmable Current Source
5V
5V < V < 100V
S
FOR R ≤ 50Ω
8
L
0.1µF
V
CC
1
2
3
(D )(4.096)
IN
CLK
R
L
I
=
OUT
(65536)(R )
7
3
2
7
A
V
LTC1655
µP
+
D
OUT
IN
≈ 0mA TO 10mA
6
Q1
2N3440
LT1218
CS/LD
–
GND
5
4
R
A
412Ω
1%
1655/55L TA04
13
LTC1655/LTC1655L
U
Dimensions in inches (millimeters) unless otherwise noted.
PACKAGE DESCRIPTION
N8 Package
8-Lead PDIP (Narrow 0.300)
(LTC DWG # 05-08-1510)
0.400*
(10.160)
MAX
8
7
6
5
4
0.255 ± 0.015*
(6.477 ± 0.381)
1
2
3
0.130 ± 0.005
0.300 – 0.325
0.045 – 0.065
(3.302 ± 0.127)
(1.143 – 1.651)
(7.620 – 8.255)
0.065
(1.651)
TYP
0.009 – 0.015
(0.229 – 0.381)
0.125
0.020
(0.508)
MIN
(3.175)
MIN
+0.035
0.325
–0.015
0.018 ± 0.003
(0.457 ± 0.076)
0.100
(2.54)
BSC
+0.889
8.255
(
)
N8 1098
–0.381
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm)
14
LTC1655/LTC1655L
U
Dimensions in inches (millimeters) unless otherwise noted.
PACKAGE DESCRIPTION
S8 Package
8-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.189 – 0.197*
(4.801 – 5.004)
7
5
8
6
0.150 – 0.157**
(3.810 – 3.988)
0.228 – 0.244
(5.791 – 6.197)
1
3
4
2
0.010 – 0.020
(0.254 – 0.508)
× 45°
0.053 – 0.069
(1.346 – 1.752)
0.004 – 0.010
(0.101 – 0.254)
0.008 – 0.010
(0.203 – 0.254)
0°– 8° TYP
0.016 – 0.050
(0.406 – 1.270)
0.050
(1.270)
BSC
0.014 – 0.019
(0.355 – 0.483)
TYP
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
SO8 1298
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tationthattheinterconnectionofitscircuitsasdescribedhereinwillnotinfringeonexistingpatentrights.
15
LTC1655/LTC1655L
U
TYPICAL APPLICATION
This circuit shows how to measure negative offset. Since
LTC1655/LTC1655L operate on a single supply, if its
offset is negative, the output for code 0 limits to 0V. To
measure this negative offset, a negative supply is needed.
Connect resistor R1 as shown in the figure below. The
output voltage is the offset when code 0 is loaded in.
Negative Offset Measurement
5V
0.1µF
8
V
CC
1
2
3
CLK
LTC1655/
LTC1655L
7
µP
V
OUT
D
IN
R1
100k
CS/LD
GND
5
–5V
1655/55L TA06
RELATED PARTS
PART
NUMBER
DESCRIPTION
COMMENTS
5V to 15V Single Supply, Complete V
LTC1257
Single 12-Bit V
DAC, Full Scale: 2.048V, V : 4.75V to 15.75V,
DAC SO-8 Package
OUT
OUT
CC
in Reference Can Be Overdriven Up to 12V, i.e., FS
= 12V
MAX
LTC1446/ Dual 12-Bit V
LTC1446L
DACs in SO-8 Package
LTC1446: V = 4.5V to 5.5V, V
= 0V to 4.095V
OUT
CC
OUT
LTC1446L: V = 2.7V to 5.5V, V
= 0V to 2.5V
CC
OUT
LTC1448
Dual 12-Bit V
DAC, V : 2.7V to 5.5V
Output Swings from GND to REF. REF Input Can Be Tied to V
CC
OUT
CC
LTC1450/ Single 12-Bit V
LTC1450L
DACs with Parallel Interface
LTC1450: V = 4.5V to 5.5V, V
= 0V to 4.095V
OUT
CC
OUT
LTC1450L: V = 2.7V to 5.5V, V
= 0V to 2.5V
CC
OUT
LTC1451
LTC1452
LTC1453
Single Rail-to-Rail 12-Bit DAC, Full Scale: 4.095V, V : 4.5V to 5.5V,
Internal 2.048V Reference Brought Out to Pin
5V, Low Power Complete V
DAC in SO-8 Package
CC
OUT
Single Rail-to-Rail 12-Bit V
Multiplying DAC, V : 2.7V to 5.5V
Low Power, Multiplying V
DAC with Rail-to-Rail
OUT
CC
OUT
Buffer Amplifier in SO-8 Package
Single Rail-to-Rail 12-Bit V
DAC, Full Scale: 2.5V, V : 2.7V to 5.5V 3V, Low Power, Complete V DAC in SO-8 Package
OUT
CC
OUT
LTC1454/ Dual 12-Bit V
LTC1454L
DACs in SO-16 Package with Added Functionality
LTC1454: V = 4.5V to 5.5V, V
= 0V to 4.095V
OUT
CC
OUT
LTC1454L: V = 2.7V to 5.5V, V
= 0V to 2.5V
CC
OUT
LTC1456
Single Rail-to-Rail Output 12-Bit DAC with Clear Pin,
Full Scale: 4.095V, V : 4.5V to 5.5V
Low Power, Complete V
Package with Clear Pin
DAC in SO-8
OUT
CC
LTC1458/ Quad 12 Bit Rail-to-Rail Output DACs with Added Functionality
LTC1458L
LTC1458: V = 4.5V to 5.5V, V
= 0V to 4.095V
CC
OUT
LTC1458L: V = 2.7V to 5.5V, V
= 0V to 2.5V
CC
OUT
LTC1650
Single 16-Bit V
Industrial DAC in 16-Pin SO, V = ±5V
Low Power, Deglitched, 4-Quadrant Mulitplying V
Output Swing ±4.5V
DAC,
OUT
CC
OUT
LTC1654
Dual 14-Bit DAC
1LSB DNL, 2 DACs in SO-8 Footprint
LTC1657/ Single 16-Bit V
LTC1657L
DAC with Parallel Interface
LTC1657: V = 5V, Low Power, Deglitched, V
= 0V to 4.096V
OUT
CC
OUT
LTC1657L: V = 3V, Low Power, Deglitched, V
= 0V to 2.5V
CC
OUT
LTC1658
Single Rail-to-Rail 14-Bit V
DAC in 8-Pin MSOP,
DAC in 8-Pin MSOP,
Low Power, Multiplying V
Swings from GND to REF. REF Input Can Be Tied to V
DAC in MS8 Package. Output
OUT
OUT
OUT
V
= 2.7V to 5.5V
CC
CC
LTC1659
Single Rail-to-Rail 12-Bit V
= 2.7V to 5.5V
Low Power, Multiplying V
DAC in MS8 Package. Output
OUT
V
Swings from GND to REF. REF Input Can Be Tied to V
CC
CC
16555lf LT/TP 0800 4K • PRINTED IN USA
LINEAR TECHNOLOGY CORPORATION 1998
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
16
●
●
(408)432-1900 FAX:(408)434-0507 www.linear-tech.com
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