AD5555CRU Analog Devices Inc, AD5555CRU Datasheet - Page 9

• Manufacturer Part Number: AD5555CRU
• Description: IC DAC 14BIT DUAL SRL IN 16TSSOP
• Manufacturer: Analog Devices Inc

Specifications of AD5555CRU

• Rohs Status: RoHS non-compliant
• Settling Time: 500ns
• Number Of Bits: 14
• Data Interface: Serial
• Number Of Converters: 2
• Voltage Supply Source: Single Supply
• Power Dissipation (max): 55µW
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 16-TSSOP

THEORY OF OPERATION
The AD5545/AD5555 contain a 16-/14-bit, current-output,
digital-to-analog converter, a serial-input register, and a DAC
register. Both parts require a minimum of a 3-wire serial data
interface with an additional LDAC for dual channel simultaneous
update.
DIGITAL-TO-ANALOG CONVERTER
The DAC architecture uses a current-steering R-2R ladder
design. Figure 16 shows the typical equivalent DAC. The DAC
contains a matching feedback resistor for use with an external
I-to-V converter amplifier. The R
output of the external amplifier. The I
to the inverting input of the external amplifier. These DACs are
designed to operate with both negative or positive reference
voltages. The V
the DAC switches on and off. Note that a matching switch is
used in series with the internal 5 kΩ feedback resistor. If users
attempt to measure the R
to achieve continuity. The V
(D) loaded into the corresponding DAC register, according to
Equation 1 and Equation 2, determine the DAC output voltage.
Note that the output full-scale polarity is the opposite of the
V
REF
V
polarity for dc reference voltages.
V
V
REF
OUT
OUT
DIGITAL INTERFACE CONNECTIONS OMITTED FOR CLARITY:
SWITCHES S1 AND S2 ARE CLOSED, V
2R
=
=
–
–
V
V
DD
REF
REF
Figure 16. Equivalent R-2R DAC Circuit
R
power pin is used only by the logic to drive
×
×
2R
D
D
/
/
16
65
FB
,
,
384
536
value, power must be applied to V
REF
R
2R
input voltage and the digital data
FB
pin is connected to the
R
OUT
DD
R
MUST BE POWERED
terminal is connected
S2
5kΩ
02918- 0- 005
S1
V
R
I
GND
OUT
DD
FB
Rev. C | Page 9 of 20
DD
(1)
(2)
These DACs are also designed to accommodate ac reference input
signals. The AD5545/AD5555 accommodate input reference
voltages in the range of –12 V to +12 V. The reference voltage
inputs exhibit a constant nominal input-resistance value of
5 kΩ, ±30%. The DAC output (I
ducing various output resistances and capacitances. When
choosing an external amplifier, the user should take into
account the variation in impedance generated by the AD5545/
AD5555 on the amplifiers inverting input node. The feedback
resistance in parallel with the DAC ladder resistance dominates
output voltage noise.
V
REF
A
DIGITAL INTERFACE CONNECTIONS OMITTED FOR CLARITY:
SWITCHES S1 AND S2 ARE CLOSED, V
2R
AD5545/AD5555
2.500V
R
Figure 17. Recommended System Connections
2R
R
2R
V
OUT
V
ADR03
R
IN
DD
R
GND
MUST BE POWERED
OUT
S2
) is code dependent, pro-
5kΩ
V
DD
AD5545/AD5555
S1
A
GND
5V
R
I
A
OUT
FB
A
A
AD8628
+3V
–3V
02918- 0- 006
V
V
CC
EE
LOAD
V
OUT