max5858 Maxim Integrated Products, Inc., max5858 Datasheet - Page 17

• Manufacturer Part Number: max5858
• Description: Max5858 Dual, 10-bit, 300msps, Current-output Dac With 4x/2x/1x Interpolation Filters
• Manufacturer: Maxim Integrated Products, Inc.

Apply an external clock to CLKXP and CLKXN at the
desired DAC update rate and allowable input ampli-
tude. CLK is an output and provides the signal neces-
sary to synchronize the input data. CLKXP and CLKXN
accept a frequency range of 0 to 300MHz (see Table
5). Maintain a low capacitive load at the CLK output
(not higher than 10pF for f
The MAX5858 provides an integrated 50ppm/°C, 1.24V,
low-noise bandgap reference that can be disabled and
overridden with an external reference voltage. REFO
serves either as an external reference input or an inte-
grated reference output. If REN is connected to AGND,
the internal reference is selected and REFO provides a
1.24V (50µA) output. Buffer REFO with an external
amplifier, when driving a heavy load.
The MAX5858 also employs a control amplifier
designed to simultaneously regulate the full-scale out-
put current (I
Calculate the output current as:
where I
V
Figure 4. Setting IFS with the Internal 1.24V Reference and the Control Amplifier
Dual, 10-Bit, 300Msps, Current-Output DAC with
REFO
*COMPENSATION CAPACITOR (C
Internal Reference and Control Amplifier
/R
REF
SET
) and I
is the reference output current (I
FS
) for both outputs of the devices.
______________________________________________________________________________________
AGND
FS
OPTIONAL EXTERNAL BUFFER
FOR HEAVIER LOADS
I
FS
COMP
is the full-scale output current.
= 32
MAX4040
CLK
≈ 100nF).
I
REF
✕
of 165MHz).
I
=
REF
V
R
REF
SET
Clocking Modes
AGND
C
COMP
4x/2x/1x Interpolation Filters
*
R
SET
REF
REFO
REFR
=
I
REF
R
fier output current of the MAX5858 (Figure 4). This cur-
rent is mirrored into the current-source array where I
is equally distributed between matched current seg-
ments and summed to valid output current readings for
the DACs.
To disable the internal reference of the MAX5858, con-
nect REN to AV
reference to drive the REFO to set the full-scale output
(Figure 5). For improved accuracy and drift performance,
choose a fixed output voltage reference such as the
1.24V, 25ppm/°C MAX6520 bandgap reference.
The MAX5858 accepts an input data rate up to 165MHz
or the DAC conversion rate of 300MHz. The input latch-
es on the rising edge of the clock, whereas the output
latches on the following rising edge.
Figure 6 depicts the write cycle of the DACs in 4x inter-
polation mode. In this timing diagram, signals applied
to CLKXP and CLKXN are divided by four to create the
DAC’s CLK signal. The MAX5858 DAC output is updat-
ed at the rate of the clock applied to CLKXP/CLKXN.
SET
is the reference resistor that determines the ampli-
REFERENCE
REN
BANDGAP
1.24V
DD
MAX5858
. Apply a temperature-stable, external
AGND
External Reference
Detailed Timing
SOURCE ARRAY
CURRENT-
I
FS
17
FS