LTC2758_15 Datasheet, PDF (5/24 Pages) Linear Technology – Dual Serial 18-Bit SoftSpan IOUT DACs

LTC2758
TIMING CHARACTERISTICS The l denotes specifications that apply over the full operating temperature range,
otherwise specifications are at T_A = 25°C.
SYMBOL PARAMETER
CONDITIONS
MIN TYP MAX UNITS
t₇
CS/LD Low to SCK Positive Edge
l
5
ns
t₈
CS/LD High to SCK Positive Edge
l
5
ns
t₉
SRO Propagation Delay
C_LOAD = 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
C_LOAD = 10pF (Note 13)
l
70
ns
t₁₃
CS/LD High to RFLAG high
C_LOAD = 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 I_OUT1 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 R_INX to R_COMX; feedback resistors
measured from R_COMX to REFX.
Note 5: DAC input resistance is independent of code.
Note 6: Parallel combination of the resistances from the specified pin to
I_OUT1X and from the specified pin to I_OUT2X.
Note 7: Using LT1468 with C_FEEDBACK = 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; C_FB = 50pF.
Note 9: Full-scale transition; REF = 0V.
Note 10: Analog Crosstalk is defined as the AC voltage ratio V_OUTB/V_REFA,
expressed in dB. REFB is grounded, and DAC B is set to 0V-5V span and
zero-, mid- or full- scale code. V_REFA is a 3V_RMS, 1kHz sine wave.
Note 11: REF = 6V_RMS at 1kHz. 0V to 5V range. DAC code = FS. Output
amplifier = LT1468.
Note 12: Calculation from V_n = √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 f_MAX is limited by
SRO propagation delay t₉ as follows:
( ) ^fMAX
=



2
1
t₉ +
t_S



,
where
t_S
is
the
setup
time
of
the
receiving
device.
For more information www.linear.com/LTC2758
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