MAX5893 Maxim Integrated Products, MAX5893 Datasheet - Page 28
MAX5893
Manufacturer Part Number
MAX5893
Description
12-Bit/ 500Msps Interpolating and Modulating Dual DAC with CMOS Inputs
Manufacturer
Maxim Integrated Products
Datasheet
1.MAX5893.pdf
(32 pages)
For stable operation with the internal reference, REFIO
should be decoupled to GND with a 1µF capacitor.
REFIO must be buffered with an external amplifier, if
heavy loading is required, due to its 10kΩ output resis-
tance.
Alternatively, apply a temperature-stable external refer-
ence to REFIO (Figure 18). The internal reference is over-
driven by the external reference. For improved accuracy
and drift performance, choose a fixed output voltage ref-
erence such as the MAX6520 bandgap reference.
The MAX5893’s reference circuit (Figure 19) employs a
control amplifier, designed to regulate the full-scale
12-Bit, 500Msps Interpolating and Modulating
Dual DAC with CMOS Inputs
Figure 18. Typical External Reference Circuit
28
Table 5. I
* Terminated into a 50 Ω load.
REFERENCE
EXTERNAL
______________________________________________________________________________________
1.25V
FULL-SCALE
I
OUTFS
CURRENT
10
15
20
I
REF
2
5
OUTFS
(mA)
R
1µF
SET
DACREF
FSADJ
REFIO
and R
REFERENCE
REFERENCE
SET
CURRENT
1.2V
I
REF
156.26
312.50
468.75
625.00
62.50
10kΩ
Selection Matrix Based on a Typical 1.20V Reference Voltage
(µA)
MAX5893
ARRAY DAC
CURRENT-
SOURCE
CALCULATED
19.2k
7.68k
3.84k
2.56k
1.92k
current I
DAC. The output current can be calculated as:
where I
V
of the DAC. Located between FSADJ and DACREF,
R
amplifier’s output current for the DAC. Use Table 5 for a
matrix of different I
Figure 19. MAX5893 Internal Reference Architecture
R
REFIO
SET
SET
1µF
I
REF
(Ω)
is the reference resistor, which determines the
/R
REFIO
OUT
SET
R
SET
DACREF
1% EIA STD
I
FSADJ
OUTFS
REFIO
) and I
for the differential current outputs of the
I
is the reference output current (I
19.1k
3.83k
2.55k
1.91k
OUTFS
7.5k
OUTFS
= 32 x I
OUT
REFERENCE
= 32 x I
1.2V
is the full-scale output current
10kΩ
and R
REFIO
REFIO
SET
- (I
OUTPUT VOLTAGE
V
www.DataSheet4U.com
IOUTP/N
- 1LSB
OUT
selections.
MAX5893
ARRAY DAC
CURRENT-
/2
1000
SOURCE
100
250
500
750
12
* (mV
)
P-P
REFIO
)
=