4 脳 12-Bit and 4 脳 16-Bit Octal DAC with
On-Chip Reference in 14-Lead TSSOP
AD5678
FEATURES
Low power octal DAC with
Four 16-bit DACs
Four 12-bit DACs
14-lead/16-lead TSSOP
On-chip 1.25 V/2.5 V, 5 ppm/掳C reference
Power down to 400 nA @ 5 V, 200 nA @ 3 V
2.7 V to 5.5 V power supply
Guaranteed monotonic by design
Power-on reset to zero scale
3 power-down functions
Hardware LDAC and LDAC override function
CLR function to programmable code
Rail-to-rail operation
AD5678
LDAC
INPUT
REGISTER
INPUT
REGISTER
SCLK
INTERFACE
LOGIC
INPUT
REGISTER
INPUT
REGISTER
INPUT
REGISTER
INPUT
REGISTER
INPUT
REGISTER
INPUT
REGISTER
POWER-ON
RESET
LDAC
1
CLR
1
1
RU-16
FUNCTIONAL BLOCK DIAGRAM
V
DD
V
REFIN
/V
REFOUT
1.25V/2.5V
REF
DAC
REGISTER
DAC
REGISTER
DAC
REGISTER
DAC
REGISTER
DAC
REGISTER
DAC
REGISTER
DAC
REGISTER
DAC
REGISTER
STRING
DAC A
STRING
DAC B
STRING
DAC C
STRING
DAC D
STRING
DAC E
STRING
DAC F
STRING
DAC G
STRING
DAC H
BUFFER
V
OUT
A
BUFFER
V
OUT
B
BUFFER
V
OUT
C
SYNC
BUFFER
V
OUT
D
DIN
BUFFER
V
OUT
E
BUFFER
V
OUT
F
BUFFER
V
OUT
G
BUFFER
V
OUT
H
POWER-DOWN
LOGIC
GND
05299-001
APPLICATIONS
Process control
Data acquisition systems
Portable battery-powered instruments
Digital gain and offset adjustment
Programmable voltage current sources
Programmable attenuators
PACKAGE ONLY
Figure 1.
GENERAL DESCRIPTION
The AD5678 is a low power, octal, buffered voltage-output
DAC with four 12-bit DACs and four 16-bit DACs in a single
package. All devices operate from a single 2.7 V to 5.5 V supply
and are guaranteed monotonic by design.
The AD5678 has an on-chip reference with an internal gain of 2.
The AD5678-1 has a 1.25 V 5 ppm/掳C reference, giving a full-
scale output of 2.5 V; the AD5678-2 has a 2.5 V 5 ppm/掳C
reference, giving a full-scale output of 5 V. The on-board
reference is off at power-up, allowing the use of an external
reference. The internal reference is enabled via a software write.
The part incorporates a power-on reset circuit that ensures that
the DAC output powers up to 0 V and remains powered up at
this level until a valid write takes place. The part contains a
power-down feature that reduces the current consumption of
the device to 400 nA at 5 V and provides software-selectable
output loads while in power-down mode for any or all DAC
channels.
The outputs of all DACs can be updated simultaneously using
the LDAC function, with the added functionality of user-
selectable DAC channels to simultaneously update. There is
also an asynchronous CLR that clears all DACs to a software-
selectable code鈥? V, midscale, or full scale.
The AD5678 utilizes a versatile 3-wire serial interface that
operates at clock rates of up to 50 MHz and is compatible with
standard SPI庐, QSPI鈩? MICROWIRE鈩? and DSP interface
standards. The on-chip precision output amplifier enables rail-
to-rail output swing.
PRODUCT HIGHLIGHTS
1.
2.
3.
4.
5.
Octal DAC (four 12-bit DACs and four 16-bit DACs).
On-chip 1.25 V/2.5 V, 5 ppm/掳C reference.
Available in 14-lead/16-lead TSSOP.
Power-on reset to 0 V.
Power-down capability. When powered down, the DAC
typically consumes 200 nA at 3 V and 400 nA at 5 V.
Rev. A
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rights of third parties that may result from its use. Specifications subject to change without notice. No
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