AD5452YRMZ Analog Devices Inc, AD5452YRMZ Datasheet - Page 15

• Manufacturer Part Number: AD5452YRMZ
• Description: IC DAC 12BIT MULT 50MHZ 8-MSOP
• Manufacturer: Analog Devices Inc

Specifications of AD5452YRMZ

• Data Interface: Serial
• Design Resources: Unipolar, Precision DC Digital-to-Analog Conversion using AD5450/1/2/3 8-14-Bit DACs (CN0052) Precision, Bipolar, Configuration for AD5450/1/2/3 8-14bit Multiplying DACs (CN0053) AC Signal Processing Using AD5450/1/2/3 Current Output DACs (CN0054) Programmable Gain Element Using AD5450/1/2/3 Current Output DAC Family (CN0055) Single Supply Low Noise LED Current Source Driver Using a Current Output DAC in the Reverse Mode (CN0139)
• Settling Time: 110ns
• Number Of Bits: 12
• Number Of Converters: 1
• Voltage Supply Source: Single Supply
• Power Dissipation (max): 55µW
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-MSOP, Micro8™, 8-uMAX, 8-uSOP,
• Resolution (bits): 12bit
• Sampling Rate: 2.7MSPS
• Input Channel Type: Serial
• Supply Voltage Range - Analogue: 2.5V To 5.5V
• Supply Current: 400nA
• Digital Ic Case: RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

GENERAL DESCRIPTION
DAC SECTION
The AD5450, AD5451 and AD5452 are 8-, 10- and 12-bit
current output DACs, consisting of a segmented (4 bits)
inverting R-2R ladder configuration. A simplified diagram for
the 12-bit AD5452 is shown in Figure 39.
The feedback resistor R
typically 9 kΩ (minimum 7 kΩ and maximum 11 kΩ). If I
is kept at the same potential as GND, a constant current flows in
each ladder leg, regardless of digital input code. Therefore, the
input resistance presented at V
nominally of value R. The DAC output (I
dependent, producing various resistances and capacitances.
When choosing the external amplifier, take into account the
variation in impedance generated by the DAC on the amplifier’s
inverting input node.
Access is provided to the V
DAC, making the device extremely versatile and allowing it to
be configured in several different operating modes; for example,
it can provide a unipolar output or to provide 4-quadrant
multipli-cation in bipolar mode. Note that a matching switch is
used in series with the internal R
attempt to measure R
continuity.
CIRCUIT OPERATION
Unipolar Mode
Using a single op amp, these devices can easily be configured to
provide a 2-quadrant multiplying operation or a unipolar output
voltage swing, as shown in Figure 40. When an output amplifier
is connected in unipolar mode, the output voltage is given by:
where:
D is the fractional representation of the digital word loaded to
the DAC.
D
n is the number of bits.
V
V
REF
OUT
= 0 to 255 (8-bit AD5450)
= 0 to 1023 (10-bit AD5451)
= 0 to 4095 (12-bit AD5452)
=
−
2R
S1
2
D
R
n
DAC DATA LATCHES
×
AND DRIVERS
V
Figure 39. Simplified Ladder
2R
FB
S2
REF
R
, power must be applied to V
FB
has a value of R. The value of R is
REF
2R
S3
, R
REF
FB
FB
R
is always constant and
, and I
feedback resistor. If users
2R
S12
OUT
OUT
1 terminals of the
1) is code
2R
R
AGND
DD
to achieve
R
I
OUT
FB
1
OUT
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1
Note that the output voltage polarity is opposite to the V
polarity for dc reference voltages.
These DACs are designed to operate either with negative or
positive reference voltages. The V
the internal digital logic to drive the on and off states of the
DAC switches.
These DACs also are designed to accommodate ac reference
input signals in the range of −10 V to +10 V.
With a fixed 10 V reference, the circuit shown in Figure 40 gives
a unipolar 0 V to −10 V output voltage swing. When V
signal, the circuit performs 2-quadrant multiplication.
Table 5 shows the relationship between the digital code and the
expected output voltage for a unipolar operation using the 8-bit
AD5450.
Table 5. Unipolar Code Table for AD5450
Digital Input
1111 1111
1000 0000
0000 0001
0000 0000
Bipolar Operation
In some applications, it may be necessary to generate a full
4-quadrant multiplying operation or a bipolar output swing.
This can be easily accomplished by using another external
amplifier and some external resistors, as shown in Figure 41. In
this circuit, the second amplifier, A2, provides a gain of 2.
Biasing the external amplifier with an offset from the reference
voltage results in full 4-quadrant multiplying operation. The
transfer function of this circuit shows that both negative and
positive output voltages are created as the input data (D) is
incremented from code zero (V
(V
V
NOTES
1. R1 AND R2 USED ONLY IF GAIN ADJUSTMENT IS REQUIRED.
2. C1 PHASE COMPENSATION (1pF TO 2pF) MAY BE REQUIRED
REF
IF A1 IS A HIGH SPEED AMPLIFIER.
OUT
− 0 V ) to full scale (V
R1
V
SYNC
REF
V
V
µ
DD
DD
CONTROLLER
SCLK SDIN
AD5450/
AD5451/
AD5452
Figure 40. Unipolar Operation
Analog Output (V)
−V
−V
−V
−V
REF
REF
REF
REF
AD5450/AD5451/AD5452
R
(255/256)
(128/256) = −V
(1/256)
(0/256) = 0
OUT
FB
OUT
= +V
I
GND
OUT
DD
R2
= − V
1
power pin is only used by
REF
AGND
).
REF
REF
) to midscale
C1
/2
A1
V
OUT
= 0 TO –V
IN
REF
is an ac
REF