|
|
PDF LTC2758 Data sheet ( Hoja de datos )
| Número de pieza | LTC2758 | |
| Descripción | Dual Serial 18-Bit SoftSpan Iout DACs | |
| Fabricantes | Linear | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de LTC2758 (archivo pdf) en la parte inferior de esta página. Total 24 Páginas | ||
|
No Preview Available !
FEATURES
n Maximum 18-Bit INL Error: ±1 LSB Over Temperature
n Program or Pin-Strap Six Output Ranges:
0V to 5V, 0V to 10V, –2.5V to 7.5V, ±2.5V, ±5V, ±10V
n Guaranteed Monotonic Over Temperature
n Glitch Impulse 0.4nV•s (3V), 2nV•s (5V)
n 18-Bit Settling Time: 2.1µs
n 2.7V to 5.5V Single Supply Operation
n 1µA Maximum Supply Current
n Voltage-Controlled Offset and Gain Trims
n Serial Interface with Readback of All Registers
n Clear and Power-On-Reset to 0V Regardless of
Output Range
n 48-Pin 7mm × 7mm LQFP Package
APPLICATIONS
n Instrumentation
n Medical Devices
n Automatic Test Equipment
n Process Control and Industrial Automation
LTC2758
Dual Serial 18-Bit
SoftSpan IOUT DACs
DESCRIPTION
The LTC®2758 is a dual 18-bit multiplying serial-input,
current-output digital-to-analog converter. LTC2758A
provides full 18-bit performance (INL and DNL of ±1LSB
maximum) over temperature without any adjustments.
18-bit monotonicity is guaranteed in all performance
grades. This SoftSpan™ DAC operates from a single 3V
to 5V supply and offers six output ranges (up to ±10V)
that can be programmed through the 3-wire SPI serial
interface or pin-strapped for operation in a single range.
Any on-chip register (including DAC output-range set-
tings) can be read for verification in just one instruction
cycle; and if you change register content, the altered
register will be automatically read back during the next
instruction cycle.
Voltage-controlled offset and gain adjustments are also
provided; and the power-on reset circuit and CLR pin both
reset the DAC outputs to 0V regardless of output range.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
SoftSpan is a trademark of Linear Technology Corporation. All other trademarks are the property
of their respective owners.
TYPICAL APPLICATION
Dual 18-Bit VOUT DAC with Software-Selectable Ranges
GAIN A
ADJUST
LT1012
REFERENCE
5V
5V
0.1µF
SPI WITH
READBACK
4
GEADJA ROFSA REFA
RCOMA RINA
RFBA
VDD
DAC A
LTC2758
IOUT1A
IOUT2A
VOSADJA
RFBB
27pF
–
+
LT1468
VOUTA
OFFSET A ADJUST
IOUT1B
2–7pF
DAC B
IOUT2B
+
VOUTB
GND
VOSADJB
LT1468
OFFSET B ADJUST
GEADJB ROFSB REFB
GAIN B
ADJUST
LT1012
RCOMB
RINB
2758 TA01a
REFERENCE
5V
LTC2758 Integral Nonlinearity
1.0 0V TO 10V RANGE
0.8
0.6
0.4
0.2
0
–0.2
–0.4
–0.6
–0.8
–1.0
0
65536
131072
CODE
196608 262143
2758 TA01b
For more information www.linear.com/LTC2758
2758fa
1
1 page  
LTC2758
TIMING CHARACTERISTICS The l denotes specifications that apply over the full operating temperature range,
otherwise specifications are at TA = 25°C.
SYMBOL PARAMETER
CONDITIONS
MIN TYP MAX UNITS
t7 CS/LD Low to SCK Positive Edge
l5
ns
t8 CS/LD High to SCK Positive Edge
l5
ns
t9 SRO Propagation Delay
CLOAD = 10pF
l 26 ns
t10 CLR Pulse Width Low
l 60
ns
t11 LDAC Pulse Width Low
l 20
ns
t12 CLR Low to RFLAG Low
CLOAD = 10pF (Note 13)
l
70 ns
t13 CS/LD High to RFLAG high
CLOAD = 10pF (Note 13)
l
60 ns
SCK Frequency
50% Duty Cycle (Note 14)
l
25 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: Continuous operation above the specified maximum operating
junction temperature may impair device reliability.
Note 3: Calculation from feedback resistance and IOUT1 leakage current
specifications; not production tested. In most applications, unipolar zero-
scale error is dominated by contributions from the output amplifier.
Note 4: Input resistors measured from RINX to RCOMX; feedback resistors
measured from RCOMX to REFX.
Note 5: DAC input resistance is independent of code.
Note 6: Parallel combination of the resistances from the specified pin to
IOUT1X and from the specified pin to IOUT2X.
Note 7: Using LT1468 with CFEEDBACK = 27pF. A ±0.0004% settling time
of 1.8µs can be achieved by optimizing the time constant on an individual
basis. See Application Note 120, 1ppm Settling Time Measurement for a
Monolithic 18-Bit DAC.
Note 8: Measured at the major carry transition, 0V to 5V range. Output
amplifier: LT1468; CFB = 50pF.
Note 9: Full-scale transition; REF = 0V.
Note 10: Analog Crosstalk is defined as the AC voltage ratio VOUTB/VREFA,
expressed in dB. REFB is grounded, and DAC B is set to 0V-5V span and
zero-, mid- or full- scale code. VREFA is a 3VRMS, 1kHz sine wave.
Note 11: REF = 6VRMS at 1kHz. 0V to 5V range. DAC code = FS. Output
amplifier = LT1468.
Note 12: Calculation from Vn = √4kTRB, where k = 1.38E-23 J/°K
(Boltzmann constant), R = resistance (Ω), T = temperature (°K), and B =
bandwidth (Hz). 0V to 5V Range; zero-, mid-, or full-scale.
Note 13: Guaranteed by design; not production tested.
Note 14: When using SRO, maximum SCK frequency fMAX is limited by
SRO propagation delay t9 as follows:
( )
fMAX
=
2
1
t9 +
tS
,
where
tS
is
the
setup
time
of
the
receiving
device.
For more information www.linear.com/LTC2758
2758fa
5
5 Page 
LTC2758
OPERATION
Output Ranges
The LTC2758 is a dual, current-output, serial-input precision
multiplying DAC with selectable output ranges. Ranges can
either be programmed in software for maximum flexibility
(each of the DACs can be programmed to any one of six
output ranges) or hardwired through pin-strapping. Two
unipolar ranges are available (0V to 5V and 0V to 10V), and
four bipolar ranges (±2.5V, ±5V, ±10V and –2.5V to 7.5V).
These ranges are obtained when an external precision 5V
reference is used. The output ranges for other reference
voltages are easy to calculate by observing that each range
is a multiple of the external reference voltage. The ranges
can then be expressed: 0 to 1×, 0 to 2×, ±0.5×, ±1×, ±2×,
and –0.5× to 1.5×.
Manual Span Configuration
Multiple output ranges are not needed in some applica-
tions. To configure the LTC2758 to operate in a single span
without additional operational overhead, tie the M-SPAN
pin directly to VDD. The active output range for all DACs is
then set via hardware pin strapping of pins S2, S1 and S0
(rather than through the SPI port); and Write and Update
commands have no effect on the active output span. See
Figure 1 and Table 3.
Tie the M-SPAN pin to ground for normal SoftSpan
operation.
Input and DAC Registers
The LTC2758 has 5 internal registers for each DAC, a total
of 10 registers (see Block Diagram). Each DAC channel
has two sets of double-buffered registers, one set for
the code data, and one for the output range of the DAC,
plus one readback register. Double buffering provides the
VDD
LTC2758
VDD
M-SPAN
S2
S1
S0
DAC A
DAC B
CS/LD SDI SCK
2754 F01
–
+
–
+
±10V
±10V
Figure 1. Using M-SPAN to Configure the LTC2758
for Single-Span Operation (±10V Range Shown)
capability to simultaneously update the span (output range)
and code, which allows smooth voltage transitions when
changing output ranges. It also permits the simultaneous
updating of multiple DACs.
Each set of double-buffered registers comprises an Input
register and a DAC register.
Input register: The Write operation shifts data from the
SDI pin into a chosen Input register. The Input registers
are holding buffers; Write operations do not affect the
DAC outputs.
DAC register: The Update operation copies the contents
of an Input register to its associated DAC register. The
contents of a DAC register directly updates the associated
DAC output voltage or output range.
Note that updates always include both Code and Span
register sets; but the values held in the DAC registers will
only change if the associated Input register values have
previously been altered via a Write operation.
For more information www.linear.com/LTC2758
2758fa
11
11 Page | ||
| Páginas | Total 24 Páginas | |
| PDF Descargar | [ Datasheet LTC2758.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| LTC2751 | Current Output 12-/14-/16-Bit SoftSpanTM DACs |  Linear Technology |
| LTC2752 | Dual16-Bit SoftSpan IOUT DACs | Linear Technology |
| LTC2753 | Dual Current Output 12-/14-/16-Bit SoftSpan DACs | Linear Technology |
| LTC2754 | Quad 12-Bit SoftSpan Iout DACs |  Linear Technology Corporation |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
 Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |