max5890 Maxim Integrated Products, Inc., max5890 Datasheet - Page 9

• Manufacturer Part Number: max5890
• Description: Max5890 14-bit, 600msps, High-dynamic-performance Dac With Lvds Inputs
• Manufacturer: Maxim Integrated Products, Inc.

The MAX5890 high-performance, 14-bit, current-steer-
ing DAC (see the Functional Diagram) operates with
DAC update rates up to 600Msps. The current-steering
array generates differential full-scale currents in the
2mA to 20mA range. An internal current-switching net-
work, in combination with external 50Ω termination
resistors, converts the differential output currents into a
differential output voltage with a 0.1V to 1V peak-to-
peak output voltage range. The analog outputs have a
-1.0V to +1.1V voltage compliance. For applications
requiring high dynamic performance, use the differen-
tial output configuration and limit the output voltage
swing to ±0.5V at each output. An integrated 1.2V
bandgap reference, control amplifier, and user-selec-
table external resistor determine the data converter’s
full-scale output range.
The MAX5890 operates with the internal 1.2V bandgap
reference or an external reference voltage source.
REFIO serves as the input for an external, low-imped-
ance reference source or as a reference output when
the DAC operates in internal reference mode. For sta-
ble operation with the internal reference, bypass REFIO
to AGND with a 0.1µF capacitor. The REFIO output
resistance is 10kΩ. Buffer REFIO with a high-input-
impedance amplifier when using it as a reference
source for external circuitry.
The MAX5890’s reference circuit (Figure 1) employs a
control amplifier to regulate the full-scale current,
I
Calculate the output current as follows:
where I
DAC. R
determines the amplifier’s full-scale output current for
the DAC. See Table 1 for a matrix of different I
and R
OUTFS
SET
Reference Architecture and Operation
, for the differential current outputs of the DAC.
I
14-Bit, 600Msps, High-Dynamic-Performance
OUTFS
OUTFS
SET
selections.
(located between FSADJ and DACREF)
is the full-scale output current of the
=
_______________________________________________________________________________________
32
×
Detailed Description
V
R
REFIO
SET
×



1
−
Architecture
2
14
1



OUTFS
The complementary current outputs (OUTP, OUTN) can
be connected in a single-ended or differential configu-
ration. A load resistor converts these two output cur-
rents into complementary single-ended output
voltages. A transformer or a differential amplifier con-
verts the differential voltage existing between OUTP
and OUTN to a single-ended voltage. When not using a
transformer, terminate each output with a 25Ω resistor
to ground and a 50Ω resistor between the outputs.
To generate a single-ended output, select OUTP as the
output and connect OUTN to AGND. Figure 2 shows a
simplified diagram of the internal output structure of the
MAX5890.
Table 1. I
Based on a Typical 1.200V Reference
Voltage
Figure 1. Reference Architecture, Internal Reference
Configuration
FULL-SCALE CURRENT
I
0.1µF
DAC with LVDS Inputs
REF
I
= V
REF
REFIO
I
OUTFS
R
/ R
SET
10
15
20
SET
2
5
OUTFS
(mA)
REFIO
FSADJ
DACREF
10kΩ
Analog Outputs (OUTP, OUTN)
REFERENCE
1.2V
and R
CALCULATED
SET
19.2k
7.68k
3.84k
2.56k
1.92k
Selection Matrix
CURRENT-SOURCE
R
ARRAY DAC
SET
(Ω)
1% EIA STD
19.1k
3.83k
2.55k
1.91k
7.5k
OUTN
OUTP
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