AD5532B Analog Devices, AD5532B Datasheet - Page 15

• Manufacturer Part Number: AD5532B
• Description: 32-Channel 14-bit Bipolar Voltage-Output DAC
• Manufacturer: Analog Devices

Specifications of AD5532B

• Resolution (bits): 14bit
• Dac Update Rate: 45kSPS
• Dac Settling Time: 22µs
• Max Pos Supply (v): +16.5V
• Single-supply: No
• Dac Type: Voltage Out
• Dac Input Format: Ser,SPI

APPLICATION CIRCUITS
AD5532B in a Typical ATE System
The AD5532B is ideally suited for use in automatic test
equipment. Several DACs are required to control pin drivers,
comparators, active loads, and signal timing. Traditionally,
sample-and-hold devices were used in these applications.
The AD5532B has several advantages: no refreshing is required,
there is no droop, pedestal error is eliminated, and there is no
need for extra filtering to remove glitches. Overall a higher level
of integration is achieved in a smaller area (see Figure 15).
Typical Application Circuit (DAC Mode)
The AD5532B can be used in many optical networking applications
that require a large number of DACs to perform control and
measurement functions. In the example shown in Figure 16, the
outputs of the AD5532B are amplified and used to control actuators
that determine the position of MEMS mirrors in an optical switch.
The exact position of each mirror is measured using sensors. The
sensor readings are muxed using four dual 4-channel matrix switches
(ADG739) and fed back to an 8-channel 14-bit ADC (AD7856).
The control loop is driven by an ADSP-2191M, a 16-bit fixed-
point DSP with three SPORT interfaces and two SPI ports. The
DSP uses some of these serial ports to write data to the DAC,
control the multiplexer, and read back data from the ADC.
REV. A
GENERATION
AND INHIBIT
PATTERN
AD5532B
STORED
PERIOD
DELAY
TIMING
DATA
DACs
AND
Figure 16. Typical Optical Control and
Measurement Application Circuit
Figure 15. AD5532B in an ATE System
SYSTEM BUS
32
1
FORMATTER
COMPARE
REGISTER
DAC
DAC
DAC
MIRROR
ARRAY
MEMS
ACTIVE
DRIVER
LOAD
COMPARATOR
32
1
S
E
N
S
O
R
ADSP-2191M
DAC
DAC
ADG739
MEASUREMENT
PARAMETRIC
4
UNIT
AD8544
DAC
DAC
1
8
2
SYSTEM BUS
AD7856
DUT
–15–
Typical Application Circuit (ISHA Mode)
The AD5532B can be used to set up voltage levels on 32 channels
as shown in the circuit below. An AD780 provides the 3 V refer-
ence for the AD5532B, and for the AD5541 16-bit DAC. A simple
3-wire serial interface is used to write to the AD5541. Because
the AD5541 has an output resistance of 6.25 kW (typ), the time
taken to charge/discharge the capacitance at the V
cant. Thus an AD820 is used to buffer the DAC output. Note
that it is important to minimize noise on V
laying out this circuit.
POWER SUPPLY DECOUPLING
In any circuit where accuracy is important, careful consideration
of the power supply and ground return layout helps to ensure the
rated performance. The printed circuit board on which the
AD5532B is mounted should be designed so that the analog and
digital sections are separated, and confined to certain areas of the
board. If the AD5532B is in a system where multiple devices require
an AGND-to-DGND connection, the connection should be made
at one point only. The star ground point should be established
as close as possible to the device. For supplies with multiple pins
(V
The AD5532B should have ample supply bypassing of 10 µF in
parallel with 0.1 µF on each supply located as close to the package
as possible, ideally right up against the device. The 10 µF capacitors
are the tantalum bead type. The 0.1 µF capacitor should have
low effective series resistance (ESR) and effective series induc-
tance (ESI), like the common ceramic types that provide a low
impedance path to ground at high frequencies, to handle transient
currents due to internal logic switching.
SCLK
SS
DIN
CS
Figure 17. Typical Application Circuit (ISHA Mode)
, V
AV
DD
CC
, AV
AD5541*
AD780*
*ADDITIONAL PINS OMITTED FOR CLARITY
CC
REF
V
), it is recommended to tie those pins together.
OUT
AD820
V
DD
V
OFFS_IN
OFFS_OUT
REFIN
SCLK DIN
IN
AV
AD5532B*
IN
CC
and REFIN when
AD5532B
DV
CC
IN
SYNC
V
pin is signifi-
SS
V
OUT
0–31