FEATURES
Infinite Sample-and-Hold Capability to ⴞ0.018% Accuracy
Infinite Sample-and-Hold Total Unadjusted Error ⴞ2.5 m V
High Integration:
32-Channel DAC in 12 mm ⴛ 12 mm CSPBGA
Per Channel Acquisition Time of 16 s Max
Adjustable Voltage Output Range
Output Impedance 0.5 ⍀
Output Voltage Span 10 V
Readback Capability
DSP/Microcontroller Compatible Serial Interface
Parallel Interface
Temperature Range –40ⴗC to +85ⴗC
APPLICATIONS
Optical Networks
Automatic Test Equipment
Level Setting
Instrumentation
Industrial Control Systems
Data Acquisition
Low Cost I/O
Infinite Sample-and-Hold
AD5533B
GENERAL DESCRIPTION
The AD5533B combines a 32-channel voltage translation function
with an infinite output hold capability. An analog input voltage on
the common input pin, V
tation transferred to a chosen DAC register. V
is then updated to reflect the new contents of the DAC register.
Channel selection is accomplished via the parallel address inputs
A0–A4 or via the serial input port. The output voltage range is
determined by the offset voltage at the OFFS_IN pin and the gain
of the output amplifier. It is restricted to a range from V
to V
– 2 V because of the headroom of the output amplifier.
DD
The device is operated with AV
to +5.25 V, V
= –4.75 V to –16.5 V, and VDD = +8 V to
SS
+16.5 V and requires a stable 3 V reference on REF_IN as well
as an offset voltage on OFFS_IN.
2. The AD5533B is available in a 74-lead CSPBGA with a
body size of 12 mm ⫻ 12 mm.
3. In infinite sample-and-hold mode, a total unadjusted error of
±2.5 mV is achieved by laser-trimming on-chip resistors.
, is sampled and its digital represen-
IN
= +5 V ± 5%, DVCC = +2.7 V
CC
for this DAC
OUT
*
+ 2 V
SS
FUNCTIONAL BLOCK DIAGRAM
DV
AV
CC
V
IN
TRACK / RESET
BUSY
GND
DAC
AGND
DGND
SER / PAR
*Protected by U.S. Patent No. 5,969,657; other patents pending.
AD5533B
ADC
INTERFACE
CONTROL
LOGIC
DIND
CC
OUT
REF IN REF OUT
REV. A
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties that
may result from its use. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices.
Nonlinearity±0.006% typInput Range 100 mV to 2.96 V
OUT
±0.018% maxAfter Gain and Offset Adjustment
Total Unadjusted Error (TUE)±2.5mV typSee TPC 6.
±12mV
max
Gain3.51/3.52/3.53min/typ/max
Offset Error
ANALOG INPUT (V
±1
±10mV
)
IN
mV typ
max
See TPC 2.
Input Voltage Range0 to 3VNominal Input Range
Input Lower Dead Band70mV max50 mV typ. Referred to V
IN
See Figure 5.
Input Upper Dead Band40mV max12 mV typ. Referred to V
IN
See Figure 5.
Input Current1µA max100 nA typ. V
one channel.
Input Capacitance
3
20pF typ
acquired on
IN
ANALOG INPUT (OFFS_IN)
Input Voltage Range0/4V min/maxOutput Range Restricted from
+ 2 V to VDD – 2 V
V
SS
Input Current1µA max100 nA typ
VOLTAGE REFERENCE
REF_IN
Nominal Input Voltage3.0V
Input Voltage Range
3
2.85/3.15V min/max
Input Current1µA max<1 nA typ
REF_OUT
Output Voltage3V typ
Output Impedance
Reference Temperature Coefficient
ANALOG OUTPUTS (V
Output Temperature Coefficient
DC Output Impedance0.5
Output RangeV
Resistive Load
Capacitive Load
Short-Circuit Current
DC Power Supply Rejection Ratio
DC Crosstalk
ANALOG OUTPUT (OFFS_OUT)
Output Temperature Coefficient
DC Output Impedance
3
3
0–31)
OUT
3, 5
3, 5
3
3
3
3, 4
3
3, 4
280
kΩ
typ
60ppm/°C typ
10ppm/°C typ
Ω
typ
+ 2/VDD – 2V min/max100 µA Output Load
SS
5
kΩ
min
100pF max
7mA typ
–70dB typVDD= +15 V ± 5%
–70dB typV
= –15 V ± 5%
SS
250µV maxOutputs Loaded
10ppm/°C typ
1.3
kΩ
typ
Output Range50 to REF_IN – 12mV typ
Output Current10µA maxSource Current
Capacitive Load100pF max
DIGITAL INPUTS
3
Input Current±10µA max5 µA typ
Input Low Voltage0.8V maxDV
0.4V maxDV
Input High Voltage2.4V minDV
2.0V minDV
= 5 V ± 5%
CC
= 3 V ± 10%
CC
= 5 V ± 5%
CC
= 3 V ± 10%
CC
Input Hysteresis (SCLK and CS Only)200mV typ
Input Capacitance10pF max
.
.
–2–
REV. A
AD5533B
Parameter
1
DIGITAL OUTPUTS (BUSY, D
OUT
B Version
3
)
2
UnitConditions/Comments
Output Low Voltage0.4V maxDVCC = 5 V. Sinking 200 µA.
Output High Voltage4.0V minDV
= 5 V. Sourcing 200 µA.
CC
Output Low Voltage0.4V maxDVCC = 3 V. Sinking 200 µA.
Output High Voltage2.4V minDV
High Impedance Leakage Current± 1µA maxD
High Impedance Output Capacitance15pF typD
= 3 V. Sourcing 200 µA.
CC
Only
OUT
Only
OUT
POWER REQUIREMENTS
Power Supply Voltages
V
DD
V
SS
AV
CC
DV
CC
Power Supply Currents
I
DD
I
SS
AI
CC
DI
CC
Power Dissipation
NOTES
1
See Terminology section.
2
B Version: Industrial temperature range –40°C to +85°C; typical at +25°C.
3
Guaranteed by design and characterization, not production tested.
4
AD780 as reference for the AD5533B.
5
Ensure that you do not exceed TJ (max). See Absolute Maximum Ratings.
6
Outputs unloaded.
Specifications subject to change without notice.
6
6
8/16.5V min/max
–4.75/–16.5V min/max
4.75/5.25V min/max
2.7/5.25V min/max
15mA max10 mA typ. All channels full-scale.
15mA max10 mA typ. All channels full-scale.
33mA max26 mA typ
1.5mA max1 mA typ
280mW typVDD = +10 V, VSS = –5 V
(VDD = +8 V to +16.5 V, VSS = –4.75 V to –16.5 V; AVCC = +4.75 V to +5.25 V; DVCC = +2.7 V to +5.25 V;
AC CHARACTERISTICS
All outputs unloaded. All specifications T
ParameterB Version
Output Settling Time
Acquisition Time16µs max
OFFS_IN Settling Time
Digital Feedthrough
Output Noise Spectral Density @ 1 kHz
AC Crosstalk
NOTES
1
B version: Industrial temperature range –40°C to +85°C; typical at 25°C.
2
Guaranteed by design and characterization, not production tested.
Specifications subject to change without notice.
2
2
2
2
AGND = DGND = DAC_GND = 0 V; REF_IN = 3 V; OFFS_IN = 0 V; Output Range from V
to T
MIN
, unless otherwise noted.)
MAX
1
UnitConditions/Comments
3µs max
10µs max500 pF, 5 kΩ Load; 0 V–3 V Step
2
0.2nV-s typ
400nV/√Hz typ
5nV-s typ
+ 2 V to VDD – 2 V.
SS
REV. A
–3–
AD5533B
TIMING CHARACTERISTICS
PARALLEL INTERFACE
Parameter
t
1
t
2
t
3
t
4
t
5
t
6
NOTES
1
See Parallel Interface Timing Diagram.
2
Guaranteed by design and characterization, not production tested.
Specifications subject to change without notice.
1, 2
Limit at T
(B Version)UnitConditions/Comments
0ns minCS to WR Setup Time
0ns minCS to WR Hold Time
50ns minCS Pulsewidth Low
50ns minWR Pulsewidth Low
20ns minA4–A0, CAL, OFFS_SEL to WR Setup Time
7ns minA4–A0, CAL, OFFS_SEL to WR Hold Time
SERIAL INTERFACE
Parameter
f
CLKIN
t
1
t
2
t
3
t
4
t
5
t
6
t
7
3
t
8
3
t
9
t
10
4
t
11
NOTES
1
See Serial Interface Timing Diagrams.
2
Guaranteed by design and characterization, not production tested.
3
These numbers are measured with the load circuit of Figure 2.
4
SYNC should be taken low while SCLK is low for readback.
Specifications subject to change without notice.
1, 2
Limit at T
(B Version)UnitConditions/Comments
20MHz maxSCLK Frequency
20ns minSCLK High Pulsewidth
20ns minSCLK Low Pulsewidth
15ns minSYNC Falling Edge to SCLK Falling Edge Setup Time
50ns minSYNC Low Time
10ns minDIN Setup Time
5ns minDIN Hold Time
5ns minSYNC Falling Edge to SCLK Rising Edge Setup Time for Readback
20ns maxSCLK Rising Edge to D
60ns maxSCLK Falling Edge to D
400ns min10th SCLK Falling Edge to SYNC Falling Edge for Readback
7ns minSCLK Falling Edge to SYNC Falling Edge Setup Time for
MIN
MIN
, T
, T
MAX
MAX
Readback
Valid
OUT
High Impedance
OUT
PARALLEL INTERFACE TIMING DIAGRAM
CS
WR
A4– A0 , CAL,
SEL
OFFS
Figure 1. Parallel Write (ISHA Mode Only)
OUTPUT
Figure 2. Load Circuit for D
–4–
TO
PIN
C
L
50pF
200A
200A
I
OL
1.6V
I
OH
Timing Specifications
OUT
REV. A
SERIAL INTERFACE TIMING DIAGRAMS
S
t
1
SCLK
12345678 910
AD5533B
SYNC
D
SCLK
YNC
D
OUT
t
3
IN
MSBLSB
t
2
t
4
t
5
t
6
Figure 3. 10-Bit Write (ISHA Mode and Both Readback Modes)
t
7
10
t
11
t
10
t
1
213456789
t
2
t
4
t
8
MSB
10
11
121314
t
9
LSB
Figure 4. 14-Bit Read (Both Readback Modes)
REV. A
–5–
AD5533B
ABSOLUTE MAXIMUM RATINGS
(TA = 25°C, unless otherwise noted.)
1, 2
VDD to AGND . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to +17 V
to AGND . . . . . . . . . . . . . . . . . . . . . . . . +0.3 V to –17 V
V
SS
AV
to AGND, DAC_GND . . . . . . . . . . . . . –0.3 V to +7 V
CC
to DGND . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to +7 V
DV
CC
Digital Inputs to DGND . . . . . . . . . . –0.3 V to DV
Digital Outputs to DGND . . . . . . . . . –0.3 V to DV
+ 0.3 V
CC
+ 0.3 V
CC
REF_IN to AGND, DAC_GND . . . . –0.3 V to AVCC + 0.3 V
to AGND, DAC_GND . . . . . . . . –0.3 V to AV
V
IN
0–31 to AGND . . . . . . . . . . VSS – 0.3 V to V
V
OUT
OFFS_IN to AGND . . . . . . . . . . VSS – 0.3 V to V
OFFS_OUT to AGND . . . . AGND – 0.3 V to AV
+ 0.3 V
CC
+ 0.3 V
DD
+ 0.3 V
DD
+ 0.3 V
CC
AGND to DGND . . . . . . . . . . . . . . . . . . . . –0.3 V to +0.3 V
Time at Peak Temperature . . . . . . . . . . . . 10 sec to 40 sec
)/θ
Max Power Dissipation . . . . . . . . . . . . (150°C – T
mW
A
JA
Max Continuous Load Current at TJ = 70°C,
per Channel Group . . . . . . . . . . . . . . . . . . . . . . . 15.5 mA
NOTES
1
Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the
device at these or any other conditions above those listed in the operational sections
of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
2
Transient currents of up to 100 mA will not cause SCR latch-up.
3
This limit includes load power.
4
This maximum allowed continuous load current is spread over eight channels,
with channels grouped as follows:
Group 1: Channels 3, 4, 5, 6, 7, 8, 9, 10
Group 2: Channels 14, 16, 18, 20, 21, 24, 25, 26
Group 3: Channels 15, 17, 19, 22, 23, 27, 28, 29
Group 4: Channels 0, 1, 2, 11, 12, 13, 30, 31
For higher junction temperatures, derate as follows:
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily
accumulate on the human body and test equipment and can discharge without detection. Although
WARNING!
the AD5533B features proprietary ESD protection circuitry, permanent damage may occur on
devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are
recommended to avoid performance degradation or loss of functionality.
(1–2)Analog Supply Pins. Voltage range from 4.75 V to 5.25 V.
CC
V
(1–4)VDD Supply Pins. Voltage range from 8 V to 16.5 V.
DD
V
(1–4)VSS Supply Pins. Voltage range from –4.75 V to –16.5 V.
SS
DGNDDigital GND Pins
DV
CC
DAC_GND (1–2)Reference GND Supply for all the DACs
REF_INReference Voltage for Channels 0–31
REF_OUTReference Output Voltage
V
(0–31)Analog Output Voltages from the 32 Channels
OUT
V
IN
1
A4–A1
CAL
2
, A0
1
CS/SYNCThis pin is both the active low chip select pin for the parallel interface and the frame synchronization pin for
1
WR
OFFSET_SEL
2
SCLK
2
D
IN
D
OUT
SER/PAR
1
1
OFFS_INOffset Input. The user can supply a voltage here to offset the output span. OFFS_OUT can also be tied to
OFFS_OUTOffset Output. This is the acquired/programmed offset voltage that can be tied to the OFFS_IN pin to
BUSYThis output tells the user when the input voltage is being acquired. It goes low during acquisition and
TRACK/RESET
NOTES
1
Internal pull-down devices on these logic inputs. Therefore, they can be left floating and will default to a logic low condition.
2
Internal pull-up devices on these logic inputs. Therefore, they can be left floating and will default to a logic high condition.
Digital Supply Pins. Voltage range from 2.7 V to 5.25 V.
Analog Input Voltage
Parallel Interface. 5-address pins for 32 channels. A4 = MSB of channel address. A0 = LSB.
Parallel Interface. Control input that allows all 32 channels to acquire VIN simultaneously.
the serial interface.
Parallel Interface. Write pin. Active low. This is used in conjunction with the CS pin to address the device
using the parallel interface.
Parallel Interface. Offset select pin. Active high. This is used to select the offset channel.
Serial Clock Input for Serial Interface. This operates at clock speeds up to 20 MHz.
Data Input for Serial Interface. Data must be valid on the falling edge of SCLK.
Output from the DAC Registers for Readback. Data is clocked out on the rising edge of SCLK and is valid
on the falling edge of SCLK.
This pin allows the user to select whether the serial or parallel interface will be used. If the pin is tied low,
the parallel interface will be used. If it is tied high, the serial interface will be used.
this pin if the user wants to drive this pin with the offset channel.
offset the span.
returns high when the acquisition operation is complete.
2
If this input is held high, VIN is acquired once the channel is addressed. While it is held low, the input to the
gain/offset stage is switched directly to V
. The addressed channel begins to acquire VIN on the rising edge
IN
of TRACK. See TRACK Input section for further information. This input can also be used as a means of
resetting the complete device to its power-on-reset conditions. This is achieved by applying a low going
pulse of between 90 ns and 200 ns to this pin. See section on RESET Function for further details.
–8–
REV. A
AD5533B
TERMINOLOGY
VIN to V
Nonlinearity
OUT
This is a measure of the maximum deviation from a straight line
passing through the endpoints of the V
versus V
IN
OUT
transfer
function. It is expressed as a percentage of the full-scale span.
Total Unadjusted Error (TUE)
This is a comprehensive specification that includes relative accuracy, gain, and offset errors. It is measured by sampling a range
of voltages on V
to the ideal value. It is expressed in mV.
V
OUT
and comparing the measured voltages on
IN
Offset Error
This is a measure of the output error when VIN = 70 mV. Ideally,
with VIN = 70 mV:
VGainGainVmV
=×− −×()(())
OUTOFFS IN
Offset error is a measure of the difference between V
and V
(ideal). It is expressed in mV and can be positive or
OUT
701
_
(actual)
OUT
negative. See Figure 5.
Gain Error
This is a measure of the span error of the analog channel. It is
the deviation in slope of the transfer function. See Figure 5. It is
calculated as:
Gain ErrorActual Full Scale Output
Ideal Full Scale Output Offset Error
=−
-
-
−
where
Ideal Full Scale OutputGainGainV
-=×− −×(.)(() )
2961
OFFS IN
_
Ideal Gain = 3.52
Output Temperature Coefficient
This is a measure of the change in analog output with changes in
temperature. It is expressed in ppm/°C.
DC Power Supply Rejection Ratio
DC Power Supply Rejection Ratio (PSRR) is a measure of
the change in analog output for a change in supply voltage
and VSS). It is expressed in dBs. VDD and VSS are varied ±5%.
(V
DD
DC Crosstalk
This is the dc change in the output level of one channel in response
to a full-scale change in the output of all other channels. It is
expressed in µV.
Output Settling Time
This is the time taken from when BUSY goes high to when the
output has settled to ±0.018%.
Acquisition Time
This is the time taken for the VIN input to be acquired. It is the
length of time that BUSY stays low.
OFFS_IN Settling Time
This is the time taken from a 0 V–3 V step change in input
voltage on OFFS_IN until the output has settled to within ±0.39%.
Digital Feedthrough
This is a measure of the impulse injected into the analog outputs
from the digital control inputs when the part is not being written
to, i.e., CS/SYNC is high. It is specified in nV-secs and is measured
with a worst-case change on the digital input pins, e.g., from all
0s to all 1s and vice versa.
Output Noise Spectral Density
This is a measure of internally generated random noise. Random
noise is characterized as a spectral density (voltage per root Hertz).
It is measured by acquiring 1.5 V on all channels and measuring
noise at the output. It is measured in nV/√Hz
typ.
AC Crosstalk
This is the area of the glitch that occurs on the output of one channel while another channel is acquiring. It is expressed in nV-secs.
REV. A
V
OUT
0V
LOWER
DEAD BAND
IDEAL
TRANSFER
FUNCTION
ACTUAL
OFFSET
ERROR
TRANSFER
FUNCTION
Figure 5. ISHA Transfer Function
–9–
GAIN ERROR +
OFFSET ERROR
2.96 3V70mV
UPPER
DEAD BAND
V
IN
AD5533B–Typical Performance Characteristics
0.0024
TA = 25 C
0.0020
V
= 3V
REFIN
= 0V
V
ERROR – V
–0.0004
OUT
V
–0.0008
–0.0012
–0.0016
–0.0020
–0.0024
0.0016
0.0012
0.0008
0.0004
0.0000
OFFS_IN
0.12.96
TPC 1. VIN to V
OUT
VIN – V
Accuracy After Offset and
Gain Adjustment
TPC 4. Acquisition Time and Output Settling Time
100
0%
5V
90
V
OUT
10
1V
BUSY
T
= 25ⴗC
A
V
= 3V
REFIN
= 0V TO 1.5V
V
IN
2
s
4
3
2
OFFSET ERROR – mV
1
0
–401200
GAIN
OFFSET ERROR
4080
TEMPERATURE – C
TPC 2. Offset Error and Gain vs. Temperature
3.530
TA = 25ⴗC
= 3V
V
REFIN
V
= 1V
IN
3.525
– V
OUT
V
3.520
3.530
3.525
3.520
3.515
3.500
GAIN
70k
60k
50k
40k
30k
FREQUENCY
20k
10k
0
TA = 25 C
= 3V
V
REFIN
VIN = 1.5V
= 0V
V
OFFS_IN
200
5.26705.26825.2676
63791
V
OUT
1545
– V
TPC 5. ISHA Mode Repeatability (64 K Acquisitions)
40
20
FREQUENCY
3.515
6–64
TPC 3. V
20–2–4
SINK/SOURCE CURRENT – mA
Source and Sink Capability
OUT
–10–
0
–48–3
–2 –101234567
TOTA L UNADJUSTED ERROR – mV
TPC 6. TUE Distribution at 25°C (ISHA Mode)
REV. A
AD5533B
FUNCTIONAL DESCRIPTION
The AD5533B can be thought of as consisting of an ADC and
32 DACs in a single package. The input voltage V
is sampled
IN
and converted into a digital word. The digital result is loaded into
one of the DAC registers and is converted (with gain and offset)
into an analog output voltage (V
OUT
0–V
31). Since the chan-
OUT
nel output voltage is effectively the output of a DAC there is no
droop associated with it. As long as power to the device is maintained, the output voltage will remain constant until this channel
is addressed again.
To update a single channel’s output voltage, the required new
voltage level is set up on the common input pin, V
. The desired
IN
channel is then addressed via the parallel port or the serial port.
When the channel address has been loaded, provided TRACK is
high, the circuit begins to acquire the correct code to load to the
DAC so that the DAC output matches the voltage on V
. The
IN
BUSY pin goes low and remains so until the acquisition is complete. The noninverting input to the output buffer is tied to V
IN
during the acquisition period to avoid spurious outputs while the
DAC acquires the correct code. The acquisition is completed in
16 µs max. The BUSY pin goes high and the updated DAC output
assumes control of the output voltage. The output voltage of the
DAC is connected to the noninverting input of the output buffer.
Since the internal DACs are offset by 70 mV (max) from GND,
the minimum V
in ISHA mode is 70 mV. The maximum VIN is
IN
2.96 V due to the upper dead band of 40 mV (max).
On power-on, all the DACs, including the offset channel, are loaded
with zeros. Each of the 33 DACs is offset internally by 50 mV (typ)
from GND so the outputs V
OUT
0 to V
31 are 50 mV (typ) on
OUT
power-on if the OFFS_IN pin is driven directly by the on-board
offset channel (OFFS_OUT), i.e., if OFFS_IN = OFFS_OUT =
50 mV = > V
= (Gain ⫻ V
OUT
– (Gain – 1) ⫻ V
DAC)
OFFS_IN
= 50 mV.
Analog Input
The equivalent analog input circuit is shown in Figure 6. The
capacitor C1 is typically 20 pF and can be attributed to pin capacitance and 32 off-channels. When a channel is selected, an extra
7.5 pF (typ) is switched in. This capacitor C2 is charged to the
previously acquired voltage on that particular channel so it must
charge/discharge to the new level. It is essential that the external
source can charge/discharge this additional capacitance within
1 µs–2 µs of channel selection so that V
can be acquired accu-
IN
rately. For this reason, a low impedance source is recommended.
ADDRESSED CHANNEL
V
IN
C1
20pF
C2
7.5pF
Figure 6. Analog Input Circuit
Large source impedances will significantly affect the performance
of the ADC. This may necessitate the use of an input buffer
amplifier.
Output Buffer Stage—Gain and Offset
The function of the output buffer stage is to translate the
50 mV–3 V typical output of the DAC to a wider range. This
is done by gaining up the DAC output by 3.52 and offsetting
the voltage by the voltage on OFFS_IN pin.
V3.52 V2.52 V
=× −×
OUTDACOFFS_IN
V
is the output of the DAC.
DAC
V
Table I shows how the output range on V
is the voltage at the OFFS_IN pin.
OFFS_IN
relates to the
OUT
offset voltage supplied by the user.
Table I. Sample Output Voltage Ranges
V
OFFS_IN
(V)V
(V)V
DAC
OUT
(V)
00.05 to 30.176 to 10.56
10.05 to 3–2.34 to +8.04
2.1300.05 to 3–5.192 to +5.192
is limited only by the headroom of the output amplifiers.
V
OUT
must be within maximum ratings.
V
OUT
Offset Voltage Channel
The offset voltage can be externally supplied by the user at
OFFS_IN or it can be supplied by an additional offset voltage
channel on the device itself. The required offset voltage is set up
and acquired by the offset DAC. This offset channel’s DAC
on V
IN
output is directly connected to OFFS_OUT. By connecting
OFFS_OUT to OFFS_IN, this offset voltage can be used as the
offset voltage for the 32 output amplifiers. It is important to
choose the offset so that V
is within maximum ratings.
OUT
REV. A
CONTROLLER
CONTROLLER
DAC
V
IN
BUSY
TRACK
ACQUISITION
ACQUISITION
CIRCUIT
CIRCUIT
ONLY ONE CHANNEL SHOWN FOR SIMPLICITY
Figure 7. Typical ATE Circuit Using
–11–
OUTPUT
OUTPUT
STAGE
STAGE
AD5533B
TRACK
V
1
OUT
Input
PIN
DRIVER
THRESHOLD
VOLTAGE
DEVICE
UNDER
TEST
AD5533B
Reset Function
The reset function on the AD5533B can be used to reset all
nodes on this device to their power-on-reset condition. This is
implemented by applying a low-going pulse of between 90 ns and
200 ns to the TRACK/RESET pin on the device. If the applied
pulse is less than 90 ns, it is assumed to be a glitch and no operation takes place. If the applied pulse is wider than 200 ns, this pin
adopts its track function on the selected channel, V
is switched to
IN
the output buffer, and an acquisition on the channel will not occur
until a rising edge of TRACK.
TRACK Function
Normally in ISHA mode of operation, TRACK is held high and
the channel begins to acquire when it is addressed. However, if
TRACK is low when the channel is addressed, V
is switched
IN
to the output buffer and an acquisition on the channel will not
occur until a rising edge of TRACK. At this stage the BUSY pin
will go low until the acquisition is complete, at which point the
DAC assumes control of the voltage to the output buffer and
is free to change again without affecting this output value.
V
IN
This is useful in an application where the user wants to ramp up
V
until V
IN
reaches a particular level (Figure 7). VIN does
OUT
not need to be acquired continuously while it is ramping up.
TRACK can be kept low and only when V
has reached its
OUT
desired voltage is TRACK brought high. At this stage, the
acquisition of V
begins.
IN
In the example shown, a desired voltage is required on the output
of the pin driver. This voltage is represented by one input to a
comparator. The microcontroller/microprocessor ramps up the
input voltage on V
the voltage on V
through a DAC. TRACK is kept low while
IN
ramps up so that VIN is not continually
IN
acquired. When the desired voltage is reached on the output of the
pin driver, the comparator output switches. The µC/µP then
knows what code is required to be input in order to obtain the
desired voltage at the DUT. The TRACK input is now brought
high and the part begins to acquire V
. BUSY goes low until V
IN
IN
has been acquired. When BUSY goes high, the output buffer
is switched from V
MODES OF OPERATION
to the output of the DAC.
IN
The AD5533B can be used in three different modes. These modes
are set by two mode bits, the first two bits in the serial word.
The 01 option (DAC Mode) is not available for the AD5533B.
For information on this mode, refer to the AD5532B data sheet.
If you attempt to set up DAC Mode, the AD5533B will enter a
test mode and a 24-clock write will be necessary to clear this.
In this standard mode, a channel is addressed and that channel
acquires the voltage on V
. This mode requires a 10-bit
IN
write (see Figure 3) to address the relevant channel
(V
OUT
0–V
31, offset channel, or all channels). MSB is
OUT
written first.
2. Acquire and Readback Mode
This mode allows the user to acquire VIN and read back the
data in a particular DAC register. The relevant channel is
addressed (10-bit write, MSB first) and VIN is acquired in 16 µs
(max). Following the acquisition, after the next falling edge
of
SYNC, the data in the relevant DAC register is clocked out
onto the D
During readback, D
line in a 14-bit serial format (see Figure 4).
OUT
is ignored. The full acquisition time
IN
must elapse before the DAC register data can be clocked out.
3. Readback Mode
Again, this is a readback mode but no acquisition is performed.
The relevant channel is addressed (10-bit write, MSB first) and
on the next falling edge of SYNC, the data in the relevant DAC
register is clocked out onto the D
OUT
line in a
(see Figure 4). The user must allow 400 ns
14-bit serial format
(min) between the
last SCLK falling edge in the 10-bit write and the falling edge
of SYNC in the 14-bit readback. The serial write and read words
can be seen in Figure 8.
This feature allows the user to read back the DAC register
code of any of the channels. Readback is useful if the system
has been calibrated and the user wants to know what code in
the DAC corresponds to a desired voltage on V
INTERFACES
Serial Interface
OUT
.
The SER/PAR pin is tied high to enable the serial interface and
to disable the parallel interface. The serial interface is controlled
by four pins as follows:
SYNC, DIN, SCLK
Standard 3-wire interface pins. The SYNC pin is shared
with the CS function of the parallel interface.
D
OUT
Data out pin for reading back the contents of the DAC registers.
The data is clocked out on the rising edge of SCLK and is
valid on the falling edge of SCLK.
Mode Bits
There are four different modes of operation as described above.
Cal Bit
When this is high, all 32 channels acquire VIN simultaneously. The
acquisition time is then 45 µs (typ) and accuracy may be reduced.
This bit is set low for normal operation.
Offset_Sel Bit
If this bit is set high, the offset channel is selected and bits
A4–A0 are ignored.
Test Bit
This must be set low for correct operation of the part.
A4–A0 Bit
Used to address any one of the 32 channels (A4 = MSB of
address, A0 = LSB).
–12–
REV. A
MSBLSB
0
TEST BIT
MODE BIT 1 MODE BIT 2
MODE BITS
CAL00
OFFSET SELA4–A0
a. 10-Bit Input Serial Write Word (ISHA Mode)
AD5533B
MSBLSB
MODE BITS
CAL01
SERIAL WORD
WRITTEN TO PART
OFFSET SELA4 –A0
TEST BIT
10-BIT
b. Input Serial Interface (Acquire and Readback Mode)
MSBLSB
011
OFFSET SELA4 –A0
MODE BITS
10-BIT
SERIAL WORD
WRITTEN TO PART
TEST BIT
c. Input Serial Interface (Readback Mode)
Figure 8. Serial Interface Formats
DB13–DB0 Bit
These are used in both readback modes to read a 14-bit word
from the addressed DAC register.
The serial interface is designed to allow easy interfacing to most
microcontrollers and DSPs, e.g., PIC16C, PIC17C, QSPI™,
SPI™, DSP56000, TMS320, and ADSP-21xx, without the
need for any glue logic. When interfacing to the 8051, the
SCLK must be inverted. The Microprocessor/Microcontroller
Interface section explains how to interface to some popular
DSPs and microcontrollers.
Figures 3 and 4 show the timing diagram for a serial read and
write to the AD5533B. The serial interface works with both a
continuous and a noncontinuous serial clock. The first falling
edge of SYNC resets a counter that counts the number of serial
clocks to ensure the correct number of bits are shifted in and out
of the serial shift registers. Any further edges on SYNC are ignored
until the correct number of bits are shifted in or out. Once the
correct number of bits have been shifted in or out, the SCLK is
ignored. In order for another serial transfer to take place, the
counter must be reset by the falling edge of SYNC. In readback,
the first rising SCLK edge after the falling edge of SYNC causes
D
to leave its high impedance state and data is clocked out
OUT
onto the D
The D
OUT
edge of the 14th SCLK. Data on the D
line and also on subsequent SCLK rising edges.
OUT
pin goes back into a high impedance state on the falling
line is latched in on the
IN
first SCLK falling edge after the falling edge of the SYNC signal
and on subsequent SCLK falling edges. The serial interface will
not shift data in or out until it receives the falling edge of the
SYNC signal.
*SPI and QSPI are trademarks of Motorola, Inc.
MSBLSB
0
0
DB13 –DB0
14-BIT DATA
READ FROM PART AFTER
NEXT FALLING EDGE OF SYNC
(DB13 = MSB OF DAC WORD)
MSBLSB
DB13 –DB0
14-BIT DATA
READ FROM PART AFTER
NEXT FALLING EDGE OF SYNC
(DB13 = MSB OF DAC WORD)
Parallel Interface
The SER/PAR bit is tied low to enable the parallel interface and
disable the serial interface. The parallel interface is controlled
by nine pins as follows:
CS
Active low package select pin. This pin is shared with the
SYNC function for the serial interface.
WR
Active low write pin. The values on the address pins are
latched on a rising edge of WR.
A4–A0
Five address pins (A4 = MSB of address, A0 = LSB). These
are used to address the relevant channel (out of a possible 32).
Offset_Sel
Offset select pin. This has the same function as the Offset_Sel
bit in the serial interface. When it is high, the offset channel
is addressed and the address on A4–A0 is ignored.
Cal
Same functionality as the Cal bit in the serial interface. When
this pin is high, all 32 channels acquire V
simultaneously.
IN
MICROPROCESSOR INTERFACING
AD5533B to ADSP-21xx Interface
The ADSP-21xx family of DSPs is easily interfaced to the
AD5533B without the need for extra logic.
A data transfer is initiated by writing a word to the TX register
after the SPORT has been enabled. In a write sequence, data is
clocked out on each rising edge of the DSP’s serial clock and
clocked into the AD5533B on the falling edge of its SCLK. In
REV. A
–13–
AD5533B
readback, 16 bits of data are clocked out of the AD5533B on
each rising edge of SCLK and clocked into the DSP on the rising
edge of SCLK. D
is ignored. The valid 14 bits of data will be
IN
centered in the 16-bit RX register when using this configuration.
The SPORT control register should be set up as follows:
TFSW= RFSW = 1, Alternate Framing
INVRFS = INVTFS = 1, Active Low Frame Signal
DTYPE = 00, Right-Justify Data
ISCLK = 1, Internal Serial Clock
TFSR= RFSR = 1, Frame Every Word
IRFS= 0, External Framing Signal
ITFS= 1, Internal Framing Signal
SLEN= 1001, 10-Bit Data-Words (ISHA Mode Write)
SLEN= 1111, 16-Bit Data-Words (Readback Mode)
Figure 9 shows the connection diagram.
AD5533B
*ADDITIONAL PINS OMITTED FOR CLARITY
*
D
OUT
SYNC
D
SCLK
IN
DR
TFS
RFS
DT
SCLK
ADSP-2101/
ADSP-2103
*
Figure 9. AD5533B to ADSP-2101/ADSP-2103 Interface
AD5533B to MC68HC11
The serial peripheral interface (SPI) on the MC68HC11 is configured for master mode (MSTR = 1), clock polarity bit (CPOL) = 0
and the clock phase bit (CPHA) = 1. The SPI is configured by
writing to the SPI control register (SPCR)— see 68HC11 UserManual. SCK of the 68HC11 drives the SCLK of the AD5533B,
the MOSI output drives the serial data line (D
and the MISO input is driven from D
OUT
) of the AD5533B,
IN
. The SYNC signal is
derived from a port line (PC7). When data is being transmitted to
the AD5533B, the SYNC line is taken low (PC7). Data appearing on the MOSI output is valid on the falling edge of SCK.
Serial data from the 68HC11 is transmitted in 8-bit bytes with
only eight falling clock edges occurring in the transmit cycle.
Data is transmitted MSB first. In order to transmit 10 data bits
in ISHA mode it is important to left-justify the data in the SPDR
register. PC7 must be pulled low to start a transfer. It is taken
high and pulled low again before any further read/write cycles
can take place. A connection diagram is shown in Figure 10.
AD5533B
*ADDITIONAL PINS OMITTED FOR CLARITY
*
SYNC
D
OUT
SCLK
D
IN
MC68HC11
MISO
PC7
SCK
MOSI
*
Figure 10. AD5533B to MC68HC11 Interface
AD5533B to PIC16C6x/7x
The PIC16C6x synchronous serial port (SSP) is configured as an
SPI Master with the clock polarity bit = 0. This is done by writing
to the Synchronous Serial Port Control Register (SSPCON). See
PIC16/17 Microcontroller User Manual. In this example I/O port
RA1 is being used to pulse SYNC and enable the serial port
of the AD5533B. This microcontroller transfers only eight bits of
data during each serial transfer operation; therefore, two consecutive read/write operations are needed for a 10-bit write and a 14-bit
readback. Figure 11 shows the connection diagram.
AD5533B
*ADDITIONAL PINS OMITTED FOR CLARITY
*
SCLK
D
OUT
D
SYNC
IN
PIC16C6x/7x
SCK/RC3
SDO/RC5
SDI /RC4
RA1
*
Figure 11. AD5533B to PIC16C6x/7x Interface
AD5533B to 8051
The AD5533B requires a clock synchronized to the serial
data. The 8051 serial interface must therefore be operated in
Mode 0. In this mode, serial data enters and exits through RxD
and a shift clock is output on TxD. Figure 12 shows how the 8051
is connected to the AD5533B. Because the AD5533B shifts data
out on the rising edge of the shift clock and latches data in on
the falling edge, the shift clock must be inverted. The AD5533B
requires its data with the MSB first. Since the 8051 outputs
the LSB first, the transmit routine must take this into account.
8051
AD5533B
*ADDITIONAL PINS OMITTED FOR CLARITY
*
SCLK
D
OUT
SYNC
D
IN
TXD
RXD
P1.1
*
Figure 12. AD5533B to 8051 Interface
APPLICATION CIRCUITS
AD5533B in a Typical ATE System
The AD5533B infinite sample-and-hold is ideally suited for use
in automatic test equipment. Several ISHAs are required to
control pin drivers, comparators, active loads, and signal timing.
Traditionally, sample-and-hold devices with droop were used in
these applications. These required refreshing to prevent the voltage
from drifting.
The AD5533B 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 13.
–14–
REV. A
AD5533B
STORED
DATA
AND INHIBIT
PATTERN
PERIOD
GENERATION
AND
DELAY
TIMING
ISHAs
ISHA
ISHA
ISHA
FORMATTER
COMPARE
REGISTER
SYSTEM BUS
ACTIVE
LOAD
DRIVER
COMPARATOR
PARAMETRIC
MEASUREMENT
ISHA
ISHA
UNIT
SYSTEM BUS
DUT
ISHA
ISHA
Figure 13. AD5533B in an ATE System
Typical Application Circuit
The AD5533B can be used to set up voltage levels on 32 channels as
shown in the circuit below. An AD780 provides the 3 V reference
for the AD5533B, 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 kΩ (typ), the time taken to charge/
discharge the capacitance at the V
pin is significant. Thus an
IN
AD820 is used to buffer the DAC output. Note that it is important
to minimize noise on V
AV
CC
CS
DIN
SCLK
AD5541*
REF
AD780*
V
OUT
*ADDITIONAL PINS OMITTED FOR CLARITY
and REFIN when laying out this circuit.
IN
AD820
AVCCDVCCV
V
DD
V
IN
AD5533B*
OFFS_IN
OFFS_OUT
REFIN
SCLK DIN
SS
V
SYNC
OUT
0–31
Figure 14. Typical Application 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
AD5533B is mounted should be designed so that the analog
and digital sections are separated and confined to certain areas
of the board. If the AD5533B 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
, VDD, AVCC) it is recommended to tie those
SS
pins together. The AD5533B 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 inductance (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.
The power supply lines of the AD5533B should use as large a trace
as possible to provide low impedance paths and reduce the effects
of glitches on the power supply line. Fast switching signals such
as clocks should be shielded with digital ground to avoid radiating
noise to other parts of the board, and should never be run near
the reference inputs. A ground line routed between the D
IN
and
SCLK lines will help reduce crosstalk between them (not required
on a multilayer board as there will be a separate ground plane,
but separating the lines will help). It is essential to minimize
noise on V
Note it is essential to minimize noise on V
Particularly for optimum ISHA performance, the V
and REFIN lines.
IN
and REFIN lines.
IN
line must
IN
be kept noise-free. Depending on the noise performance of the
board, a noise filtering capacitor may be required on the V
IN
line.
If this capacitor is necessary, then for optimum throughput it may
be necessary to buffer the source that is driving V
. Avoid cross-
IN
over of digital and analog signals. Traces on opposite sides of the
board should run at right angles to each other. This reduces the
effects of feedthrough through the board. A microstrip technique is
by far the best, but not always possible with a double-sided board.
In this technique, the component side of the board is dedicated
to ground plane while signal traces are placed on the solder side.
As is the case for all thin packages, care must be taken to avoid
flexing the CSPBGA package and to avoid a point load on the
surface of this package during the assembly process.