max5885egmtd Maxim Integrated Products, Inc., max5885egmtd Datasheet - Page 9

• Manufacturer Part Number: max5885egmtd
• Description: Max5885 3.3v, 16-bit, 200msps High Dynamic Performance Dac With Cmos Inputs
• Manufacturer: Maxim Integrated Products, Inc.

The MAX5885 is a high-performance, 16-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.
The MAX5885 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 MAX5885’s reference circuit (Figure 2) employs a
control amplifier, designed to regulate the full-scale
current I
DAC. Configured as a voltage-to-current amplifier, the
output current can be calculated as follows:
where I
V
of the DAC. Located between FSADJ and DACREF,
Table 1. I
*Terminated into a
REFIO
FULL-SCALE CURRENT
Reference Architecture and Operation
/R
REFIO
OUT
SET
I
OUT
I
OUT
10
15
20
OUT
) and I
2
5
for the differential current outputs of the
(mA)
is the reference output current (I
I
OUT
50Ω load.
= 32
and R
_______________________________________________________________________________________
= 32
OUT
✕
Detailed Description
I
is the full-scale output current
REFIO
✕
SET
I
REFIO
Performance DAC with CMOS Inputs
3.3V, 16-Bit, 200Msps High Dynamic
REFERENCE CURRENT
- (I
Selection Matrix Based on a Typical 1.200V Reference Voltage
- 1 LSB
OUT
I
REF
156.26
468.75
312.5
/ 2
62.5
625
Architecture
(µA)
16
)
REFIO
=
CALCULATED
R
amplifier’s output current for the DAC. See Table 1 for a
matrix of different I
The MAX5885 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.
Figure 2. Reference Architecture, Internal Reference
Configuration
19.2
7.68
3.84
2.56
1.92
SET
I
REF
I
REF
= V
is the reference resistor, which determines the
REFIO
0.1µF
R
SET
R
DACREF
/R
SET
FSADJ
REFIO
SET
(kΩ)
Analog Outputs (IOUTP, IOUTN)
1% EIA STD
REFERENCE
OUT
19.1
3.83
2.55
1.91
10kΩ
7.5
1.2V
and R
SET
CURRENT-STEERING
selections.
OUTPUT VOLTAGE
V
IOUTP/N
DAC
AV
DD
1000
100
250
500
750
* (mV
P-P
IOUTP
IOUTN
)
9