Datasheet

MAX5884
3.3V, 14-Bit, 200Msps High Dynamic
Performance DAC with CMOS Inputs
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Detailed Description
Architecture
The MAX5884 is a high-performance, 14-bit, current-
steering DAC (Figure 1) capable of operating with
clock speeds up to 200MHz. The converter consists of
separate input and DAC registers, followed by a cur-
rent-steering circuit. This circuit is capable of generat-
ing differential full-scale currents in the range of 2mA to
20mA. An internal current-switching network in combi-
nation with external 50Ω termination resistors convert
the differential output currents into a differential output
voltage with a peak-to-peak output voltage range of
0.1V to 1V. An integrated 1.2V bandgap reference,
control amplifier, and user-selectable external resistor
determine the data converter’s full-scale output range.
Reference Architecture and Operation
The MAX5884 supports operation with the on-chip 1.2V
bandgap reference or an external reference voltage
source. REFIO serves as the input for an external, low-
impedance reference source, and as the output if the
DAC is operating with the internal reference. For stable
operation with the internal reference, REFIO should be
decoupled to AGND with a 0.1µF capacitor. Due to its
limited output drive capability, REFIO must be buffered
with an external amplifier, if heavier loading is required.
The MAX5884’s reference circuit (Figure 2) employs a
control amplifier, designed to regulate the full-scale
current I
OUT
for the differential current outputs of the
DAC. Configured as a voltage-to-current amplifier, the
output current can be calculated as follows:
I
OUT
= 32 ✕ I
REFIO
- 1 LSB
I
OUT
= 32 ✕ I
REFIO
- (I
OUT
/ 2
14
)
where I
REFIO
is the reference output current (I
REFIO
=
V
REFIO
/R
SET
) and I
OUT
is the full-scale output current
of the DAC. Located between FSADJ and DACREF,
R
SET
is the reference resistor, which determines the
amplifier’s output current for the DAC. See Table 1 for a
matrix of different I
OUT
and R
SET
selections.
Analog Outputs (IOUTP, IOUTN)
The MAX5884 outputs two complementary currents
(IOUTP, IOUTN) that can be operated in a single-
ended or differential configuration. A load resistor can
convert these two output currents into complementary
single-ended output voltages. The differential voltage
existing between IOUTP and IOUTN can also be con-
verted to a single-ended voltage using a transformer or
a differential amplifier configuration. If no transformer is
used, the output should have a 50Ω termination to the
analog ground and a 50Ω resistor between the outputs.
0.1µF
1.2V
REFERENCE
10kΩ
I
REF
R
SET
DACREF
FSADJ
REFIO
I
REF
= V
REFIO
/R
SET
CURRENT-STEERING
DAC
AV
DD
IOUTP
IOUTN
Figure 2. Reference Architecture, Internal Reference
Configuration
R
SET
(kΩ)
FULL-SCALE CURRENT
I
OUT
(mA)
REFERENCE CURRENT
I
REF
(µA)
CALCULATED
1% EIA STD
OUTPUT VOLTAGE
V
IOUTP/N
* (mV
P-P
)
2 62.5 19.2 19.1 100
5 156.26 7.68 7.5 250
10 312.5 3.84 3.83 500
15 468.75 2.56 2.55 750
20 625 1.92 1.91 1000
Table 1. I
OUT
and R
SET
Selection Matrix Based on a Typical 1.200V Reference Voltage
*Terminated into a 50Ω load.