MAX5187 Datasheet, PDF (14/16 Pages) Maxim Integrated Products – 8-Bit, 40MHz, Current/Voltage-Output DACs

8-Bit, 40MHz, Current/Voltage-Output DACs
COUNTER
ADR
CLOCK
GENERATOR
WAVEFORM
MEMORY
(RAM)
AV_DD DV_DD
8
MAX5187
MAX5190
400Ω*
9.6k*
LOWPASS
RECONSTRUCTION
FILTER
VARIABLE
f_C
FILTERED
WAVEFORM
(ANALOG OUTPUT)
*MAX5187 ONLY
Figure 8a. Traditional Arbitrary Waveform Generation (AWG)
PIR
PHASE
INCREMENT
REGISTER
CLOCK
GENERATOR
A
D
D
E
PHASE
ACCUMULATOR
ADR
R
ACCUMULATOR
FEEDBACK LOOP
FOR DATA BITS
WAVEFORM
MEMORY
(RAM)
AV_DD DV_DD
DATA
8
MAX5187
MAX5190
REFR
400Ω*
9.6k*
LOWPASS
RECONSTRUCTION
FILTER
VARIABLE
f_C
FILTERED
WAVEFORM
(ANALOG OUTPUT)
*MAX5187 ONLY
Figure 8b. Direct Digital Synthesis AWG (DDS AWG)
ic interference (EMI) can either couple into or be gener-
ated by the MAX5187/MAX5190. Therefore, grounding
and power-supply decoupling guidelines for high-
speed, high-frequency applications should be closely
followed.
First, a multilayer PC board with separate ground and
power-supply planes is recommended. High-speed
signals should be run on controlled impedance lines
directly above the ground plane. Since the MAX5187/
MAX5190 have separate analog and digital ground
buses (AGND and DGND, respectively), the PC board
should also have separate analog and digital ground
sections with only one point connecting the two. Digital
signals should run above the digital ground plane, and
analog signals should run above the analog ground
plane.
Both devices have two power-supply inputs: analog
V_DD (AV_DD) and digital V_DD (DV_DD). Each AV_DD input
should be decoupled with parallel 10µF and 0.1µF
ceramic chip capacitors. These capacitors should be
as close to the pin as possible, and their opposite ends
should be as close as possible to the ground plane.
The DV_DD pins should also have separate 10µF and
0.1µF capacitors adjacent to their respective pins. Try
to minimize the analog load capacitance for proper
operation. For best performance, bypass with low-ESR
0.1µF capacitors to AV_DD.
The power-supply voltages should also be decoupled
with large tantalum or electrolytic capacitors at the
point they enter the PC board. Ferrite beads with addi-
tional decoupling capacitors forming a pi-network can
also improve performance.
Chip Information
TRANSISTOR COUNT: 9464
SUBSTRATE CONNECTED TO AGND
14 ______________________________________________________________________________________