max5885egmtd Maxim Integrated Products, Inc., max5885egmtd Datasheet - Page 10

• Manufacturer Part Number: max5885egmtd
• Description: Max5885 3.3v, 16-bit, 200msps High Dynamic Performance Dac With Cmos Inputs
• Manufacturer: Maxim Integrated Products, Inc.

Although not recommended because of additional
noise pickup from the ground plane, for single-ended
operation IOUTP should be selected as the output, with
IOUTN connected to AGND. Note that a single-ended
output configuration has a higher 2nd-order harmonic
distortion at high output frequencies than a differential
output configuration.
Figure 3 displays a simplified diagram of the
MAX5885’s internal output structure.
The MAX5885 features a flexible differential clock input
(CLKP, CLKN) operating from separate supplies
(VCLK, CLKGND) to achieve the best possible jitter
performance. The two clock inputs can be driven from
a single-ended or a differential clock source. For sin-
gle-ended operation, CLKP should be driven by a logic
source, while CLKN should be bypassed to AGND with
a 0.1µF capacitor.
The CLKP and CLKN pins are internally biased to V
This allows the user to AC-couple clock sources directly
to the device without external resistors to define the DC
level. The input resistance of CLKP and CLKN is >5kΩ.
See Figure 4 for a convenient and quick way to apply a
differential signal created from a single-ended source
(e.g., HP 8662A signal generator) and a wideband
transformer. These inputs can also be driven from a
CMOS-compatible clock source; however, it is recom-
mended to use sinewave or AC-coupled ECL drive for
best performance.
3.3V, 16-Bit, 200Msps High Dynamic
Performance DAC with CMOS Inputs
10
Figure 3. Simplified Analog Output Structure
SWITCHES
CURRENT
______________________________________________________________________________________
AV
DD
SOURCES
CURRENT
Clock Inputs (CLKP, CLKN)
I
OUT
IOUTN
IOUTP
CLK
I
OUT
/2.
Figure 5 shows the timing relationship between differ-
ential, digital CMOS data, clock, and output signals.
The MAX5885 features a 1.25ns hold, a 0.4ns setup,
and a 1.8ns propagation delay time. There is a 3.5
clock-cycle latency between CLKP/CLKN transitioning
high/low and IOUTP/IOUTN.
The MAX5885 features single-ended, CMOS-compatible
receivers on the bus input interface. These CMOS inputs
(B0–B15) allow for a voltage swing of 3.3V.
Segment shuffling can improve the SFDR of the
MAX5885 at higher output frequencies and amplitudes.
Note that an improvement in SFDR can only be achieved
at the cost of a slight increase in the DAC’s noise floor.
Pin SEL0 controls the segment-shuffling function. If SEL0
is pulled low, the segment-shuffling function of the DAC is
disabled. SEL0 can also be left open, because an internal
pulldown resistor helps to deactivate the segment-shuf-
fling feature. To activate the MAX5885 segment-shuffling
function, SEL0 must be pulled high.
The MAX5885 is equipped with a single-ended, CMOS-
compatible XOR input, which may be left open (XOR
provides an internal pulldown resistor) or pulled down
to DGND, if not used. Input data is XORed with the bit
applied to the XOR pin. Pulling XOR high inverts the
input data. Pulling XOR low leaves the input data nonin-
verted. By applying a pseudorandom bit stream to XOR
and applying data while XOR is high, the bit transitions
in the digital input data can be decorrelated from the
DAC output, allowing the user to troubleshoot possible
spurious or harmonic distortion degradation due to dig-
ital feedthrough on the PC board.
Figure 4. Differential Clock Signal Generation
CMOS-Compatible Digital Inputs (B0–B15)
CLOCK SOURCE
(e.g., HP 8662A)
SINGLE-ENDED
WIDEBAND RF TRANSFORMER
PERFORMS SINGLE-ENDED TO
DIFFERENTIAL CONVERSION.
1:1
Data Timing Relationship
CLKGND
Segment Shuffling (SEL0)
XOR Function (XOR)
25Ω
25Ω
0.1µF
0.1µF
CLKP
CLKN
DAC
TO