AD5452YRMZ Analog Devices Inc, AD5452YRMZ Datasheet - Page 17

• 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

Stability
In the I-to-V configuration, the I
inverting node of the op amp must be connected as close as
possible, and proper PCB layout techniques must be employed.
Because every code change corresponds to a step function, gain
peaking may occur if the op amp has limited gain bandwidth
product (GBP) and there is excessive parasitic capacitance at the
inverting node. This parasitic capacitance introduces a pole into
the open-loop response, which can cause ringing or instability
in the closed-loop applications circuit.
An optional compensation capacitor, C1, may be added in
parallel with R
41 . Too small a value of C1 can produce ringing at the output,
and too large a value can adversely affect the settling time. C1
should be found empirically, but 1 pF to 2 pF is generally
adequate for the compensation.
SINGLE-SUPPLY APPLICATIONS
Voltage-Switching Mode
Figure 42 shows these DACs operating in the voltage-switching
mode. The reference voltage, V
the output voltage is available at the V
configuration, a positive reference voltage results in a positive
output voltage, making single-supply operation possible. The
output from the DAC is voltage at a constant impedance (the
DAC ladder resistance); therefore, an op amp is necessary to
buffer the output voltage. The reference input no longer sees
constant input impedance, but one that varies with code;
therefore, the voltage input should be driven from a low
impedance source.
It is important to note that with this configuration V
to low voltages because the switches in the DAC ladder do not
have the same source-drain drive voltage. As a result, their on
resistance differs, which degrades the integral linearity of the
DAC. Also, V
internal diode turns on, causing the device to exceed the
maximum ratings. In this type of application, the full range of
multiplying capability of the DAC is lost.
Positive Output Voltage
Note that the output voltage polarity is opposite to the V
polarity for dc reference voltages. To achieve a positive voltage
NOTES
1. ADDITIONAL PINS OMITTED FOR CLARITY.
2. C1 PHASE COMPENSATION (1pF TO 2pF) MAY BE REQUIRED
V
IF A1 IS A HIGH SPEED AMPLIFIER.
IN
Figure 42. Single-Supply Voltage-Switching Mode
IN
FB
must not go negative by more than 0.3 V, or an
for stability, as shown in Figure 40 and Figure
I
OUT
1
R
FB
GND
V
V
IN
V
DD
DD
REF
, is applied to the I
OUT
of the DAC and the
R1
REF
terminal. In this
R2
OUT
IN
V
1 pin, and
OUT
is limited
REF
Rev. 0 | Page 17 of 28
output, an applied negative reference to the input of the DAC is
preferred over the output inversion through an inverting
amplifier because of the resistors’ tolerance errors. To generate a
negative reference, the reference can be level-shifted by an op
amp such that the V
the virtual ground and −2.5 V, respectively, as shown in Figure 43.
ADDING GAIN
In applications in which the output voltage is required to be
greater than V
amplifier, or it can be achieved in a single stage. It is important
to consider the effect of the temperature coefficients of the
DAC’s thin-film resistors. Simply placing a resistor in series
with the R
coefficients, and results in larger gain temperature coefficient
errors. Instead, increase the gain of the circuit by using the
recommended configuration shown in Figure 44. R1, R2, and
R3 should have similar temperature coefficients, but they need
not match the temperature coefficients of the DAC. This
approach is recommended in circuits where gains greater than 1
are required.
DIVIDER OR PROGRAMMABLE GAIN ELEMENT
Current-steering DACs are very flexible and lend themselves to
many different applications. If this type of DAC is connected as
the feedback element of an op amp and R
resistor as shown in Figure 45, then the output voltage is
inversely proportional to the digital input fraction, D.
NOTES
1. ADDITIONAL PINS OMITTED FOR CLARITY.
2. C1 PHASE COMPENSATION (1pF TO 2pF) MAY BE REQUIRED
IF A1 IS A HIGH SPEED AMPLIFIER.
V
NOTES
1. ADDITIONAL PINS OMITTED FOR CLARITY.
2. C1 PHASE COMPENSATION (1pF TO 2pF) MAY BE REQUIRED
IN
IF A1 IS A HIGH SPEED AMPLIFIER.
+5V
–5V
V
Figure 43. Positive Output Voltage with Minimum Components
OUT
ADR03
GND
R1
–2.5V
FB
V
Figure 44. Increasing Gain of Current-Output DAC
IN
resistor causes mismatches in the temperature
IN
V
V
REF
V
, gain can be added with an additional external
DD
V
V
REF
DD
DD
V
= +5V
DD
OUT
GND
GND
and GND pins of the reference become
R
R
FB
FB
AD5450/AD5451/AD5452
I
I
OUT
OUT
1
1
C1
C1
FB
is used as the input
R3
R2
V
GAIN =
R1 =
OUT
= 0V TO +2.5V
R2 + R3
V
R2R3
OUT
R2 + R3
R2