max5893egk-d Maxim Integrated Products, Inc., max5893egk-d Datasheet - Page 25

• Manufacturer Part Number: max5893egk-d
• Description: Max5893 12-bit, 500msps Interpolating And Modulating Dual Dac With Cmos Inputs
• Manufacturer: Maxim Integrated Products, Inc.

The MAX5893 features three power-saving modes.
Each DAC can be individually powered down through
bits 2 and 3 of address 00h. The interpolation filters can
also be powered down through bit 4 of address 00h,
preserving the output level of each DAC (the DACs
remain powered). Powering down both DACs will auto-
matically put the MAX5893 into full power-down, includ-
ing the interpolation filters.
System designers need to take the DAC into account
during frequency planning for high-performance appli-
cations. Proper frequency planning can ensure that
optimal system performance is achieved. The
MAX5893 is designed to deliver excellent dynamic per-
formance across wide bandwidths, as required for
communication systems. As with all DACs, some com-
binations of output frequency and update rate produce
better performance than others.
Harmonics are often folded down into the band of inter-
est. Specifically, if the DAC outputs a frequency close
to f
aliased down to:
Thus, if N ≈ (M + 1), the Mth harmonic will be close to
the output frequency. SFDR performance of a current-
steering DAC is often dominated by third-order har-
monic distortion. If this is a concern, placing the output
signal at a different frequency other than f
be considered.
Common to interpolating DACs are images near the
divided clocks. In a DAC configured for 4x interpolation
this applies to images around f
configured for 8x interpolation this applies to images
around f
are not part of the in-band (0 to f
cation, though they are a consideration for out-of-band
(f
relationship of the DATACLK to DAC update clock (see
the Data Clock section). When specifying the output
reconstruction filter for other than baseband signals,
these images should not be ignored.
DATA
S
/ N, the Mth harmonic of the output signal will be
12-Bit, 500Msps Interpolating and Modulating
/ 2 - f
S
/ 8, f
DAC
S
Applications Information
/ 4, and f
______________________________________________________________________________________
f f
/ 2) SFDR and may depend on the
=
S
−
M f
×
S
OUT
/ 2. Most of these images
Frequency Planning
S
Power-Down Mode
DATA
/ 4 and f
=
f
S
⎡
⎢
⎣
/ 2) SFDR specifi-
N M
N
−
S
/ 2. In a DAC
S
⎤
⎥
⎦
/ 4 should
Dual DAC with CMOS Inputs
The MAX5893 features synchronizers that allow for
arbitrary phase alignment between DATACLK and
CLKP/CLKN. The DATACLK causes internal switching
in the MAX5893 and the phase between DATACLK
(input mode) to CLKP/CLKN will influence the images
at DATACLK. Optimum image rejection is achieved
when DATACLK transitions are aligned with the falling
edge of CLKP. Figure 14 shows the image level near
DATACLK as a function of the DATACLK (input mode)
to CLKP/CLKN phase at 500Msps, 4x interpolation for a
10MHz, -6dBFS output signal.
The MAX5893 features a flexible differential clock input
(CLKP, CLKN) with a separate supply (AV
achieve optimum jitter performance. It uses an ultra-low
jitter clock to achieve the required noise density. Clock
jitter must be less than 0.5ps
noise density. For that reason, the CLKP/CLKN input
source must be designed carefully. The differential
clock (CLKN and CLKP) input can be driven from a sin-
gle-ended or a differential clock source. Differential
clock drive is required to achieve the best dynamic
performance from the DAC. For single-ended opera-
tion, drive CLKP with a low noise source and bypass
CLKN to GND with a 0.1µF capacitor.
The CLKP and CLKN pins are internally biased to
AV
Figure 14. Effect of CLKP/CLKN to DATACLK Phase on f
Images
CLK
/ 2. This allows the user to AC-couple clock
-100
-110
f
S
-50
-60
-70
-80
-90
/ 4 IMAGES vs. CLKP/CLKN to DATACLK DELAY
0
f
DATA
= 125MWps, 4x INTERPOLATION
2.0
CLKP/CLKN DELAY (ns)
f
f
S
S
/ 4 - f
/ 4 + f
4.0
RMS
OUT
OUT
to meet the specified
f
A
OUT
OUT
Clock Interface
6.0
= 10MHz
= -6dBFS
Data Clock
8.0
CLK
S
/ 4
) to
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