Datasheet

MAX5186/MAX5189
Dual, 8-Bit, 40MHz, Current/Voltage,
Simultaneous-Output DACs
______________________________________________________________________________________ 11
Figure 4. Timing Diagram
X = Don’t care
Table 1. Power-Down Mode Selection
CLK
INPUT SAMPLE
N - 1
FOR DAC 1
DAC 1
N - 2
N
N + 1
N + 2
N + 2
N - 2
N
N + 1
t
CH
t
CL
t
DS1
t
DS2
t
CLK
DAC 2
D0–D7
DAC 1 (N - 1)
DAC 2 (N) DAC 1 (N) DAC 2 (N + 1) DAC 1 (N + 1) DAC 2 (N + 2) DAC 1 (N + 2) DAC 2 (N + 3)
INPUT SAMPLE N
FOR DAC 2
UPDATES DAC 1
AND DAC 2 TO N
UPDATES DAC 1
AND DAC 2 TO N + 1
UPDATES DAC 1
AND DAC 2 TO N + 2
UPDATES DAC 1 AND
DAC 2 TO N - 1
PRELOADS SAMPLE N
FOR DAC 2
PRELOADS SAMPLE
N + 1 FOR DAC 2
PRELOADS SAMPLE
N + 2 FOR DAC 2
INPUT SAMPLE
N + 1
FOR DAC 2
INPUT SAMPLE
N + 2
FOR DAC 2
INPUT SAMPLE N
FOR DAC 1
INPUT SAMPLE
N + 1
FOR DAC 1
INPUT SAMPLE
N + 2
FOR DAC 1
t
DH1
t
DH2
N - 1
N - 1
Digital Feedthrough
Digital feedthrough is the noise generated on a DAC’s
output when any digital input transitions. Proper board
layout and grounding will significantly reduce this
noise, but there will always be some feedthrough
caused by the DAC itself.
Total Harmonic Distortion
Total harmonic distortion (THD) is the ratio of the RMS
sum of the input signal’s N harmonics to the fundamen-
tal itself. This is expressed as:
where V
1
is the fundamental amplitude, and V
2
through
V
N
are the amplitudes of the 2nd- through Nth-order
harmonics.
Spurious-Free Dynamic Range (SFDR)
SFDR is the ratio of RMS amplitude of the carrier frequen-
cy (maximum signal component) to the RMS value of the
next largest noise or harmonic distortion component.
SFDR is usually measured in dBc with respect to the car-
rier frequency amplitude or in dBFS with respect to the
DAC’s full-scale range. Depending on its test condition,
SFDR is observed within a predefined window or to
Nyquist. In the case of the MAX5186/MAX5189, the SFDR
performance is measured for a 0dBFS output amplitude
and analyzed within the Nyquist window.
THD 20 log
(V V V V )
V
234 N
1
222 2
=×
++ +








... ...
AGND
High-Z
AGND
High-Z
MAX5189
MAX5186
ShutdownX1
Last state prior to standby modeWake-Up10
MAX5189
MAX5186
Standby00
OUTPUT STATE
POWER-DOWN
MODE
DACEN (DAC
ENABLE)
PD
(POWER-DOWN SELECT)