DSDX Series
Digital pressure transducers
FEATURES
· 0...1 to 0...100 psi,
0...±1 to 0...±100 psi
· Absolute, gage or
differential pressure
· Digital readout via I
2
C-bus
· Precision ASIC conditioning
· Temperature compensated
· Non-ratiometric output
GENERAL DESCRIPTION
The DSDX series offers a digital
interface on a very cost-effective basis.
This family is fully calibrated and
temperature compen-sated using an
on-board ASIC. These sensors are
intended for use with non-corrosive,
non-ionic working fluids such as air
and dry gases.
APPLICATIONS
· Medical instrumentation
· Barometry
· HVAC controls
· Pneumatic controls
Devices are available to measure
absolute, differential, and gage
pressures from 1 to 100 psi. The
absolute devices have an internal
vacuum reference and an output
signal proportional to absolute
pressure. Differential devices allow
application of pressure to either side
of the sensing diaphragm and can be
used for gage or differential
measurements.
All DSDX devices are accurate to with-
in ±2.0 %FSS for all gage and
absolute devices. The devices are
characterized for operation from a
single 5 V supply. The sensor is de-
signed and manufactured according
to standards laid down in ISO 9001.
ELECTRICAL CONNECTION
+Vs
N/C
Note:
A capacitor of 220 nF is required
between +Vs and GND.
Pin 2 is an internal device connection and
should be connected to ground with a
15 nF capacitor.
It is important to place the capacitors as
close to the pins as possible!
Pins 4, 6 and 8 are internal device
connections and should not be
connected for any reason!
6
1
5
SCL
SDA
IC
15 nF
220 nF
DSDX
7
2
8 4
3
N/C
GND
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DSDX Series
Digital pressure transducers
PRESSURE SENSOR CHARACTERISTICS
Maximum ratings
Supply voltage V
S
4.75 to 5.25 V
DC
max. 6.50 V
DC
Lead temperature (2 - 4 sec.)
250°C
Environmental specifications
Temperature ranges
Compensated
Operating
Storage
Vibration:
Shock:
0 to +85°C
-20 to +105°C
-40 to +125°C
10 g at 20 - 2000 Hz
100 g for 11 ms
Caution!
The sensor is not reverse polarity protected.
Incorrect applications of excitation voltage or ground to the wrong pin can cause electrical failure.
Application of supply voltage above the maximum can cause electrical failure.
PRESSURE RANGES SPECIFICATIONS
(V
S
= 5.0 V
DC
, T
A
= 25°C)
Part number
D S D X 015A 2R
D S D X 030A 2R
D S D X 100A 2R
DSDX001G2R / D4R
DSDX005G2R / D4R
DSDX015G2R / D4R
DSDX030G2R / D4R
DSDX100G2R / D4R
D S D X 001D 4D
D S D X 005D 4D
D S D X 015D 4D
D S D X 030D 4D
D S D X 100D 4D
Pressure range
0 to 15
0 to 30
0 to 100
0 to 1
0 to 5
0 to 15
0 to 30
0 to 100
psi(g,d)
0 to ±1
0 to ±5
0 to ±15
0 to ±30
0 to ±100
psi(a)
Burst pressure
1
30
60
150
5
20
30
60
150
psi(g,d)
5
20
30
60
150
psi(a)
Sensitivity (typ.)
218
109
33
3277
655
218
109
33
1638
328
109
55
16
counts/
p si
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DSDX Series
Digital pressure transducers
PERFORMANCE CHARACTERISTICS
The output signal is not ratiometric to the supply voltage
(V
S
= 5.0 V
DC
, T
A
= 25°C)
All DSDX...R
Characteristics
Zero pressure offset
Full scale span (FSS)
2
Full scale output
Total accuracy (0 to 85°C)
3
Sample rate
Response delay
4
Startup time (power up to 1st result)
Quantization step
5
Current consumption
Min.
347
Typ.
410
3276
Max.
473
Unit
counts
3750
±2.0
%FSS
Hz
14.11
ms
40
3624
3686
100
2.73
3
6
counts
mA
All DSDX...D
Characteristics
Zero pressure offset
Full scale span (FSS)
2
Output
at max. specified pressure
at min. specified pressure
Total accuracy (0 to 85°C)
3
Sample rate
Response delay
4
Startup time (power up to 1st result)
Quantization step
5
Current consumption
Min.
1985
Typ.
2048
3276
Max.
2111
Unit
counts
3624
347
3686
410
3750
473
±2.0
100
2.73
14.11
ms
40
3
6
counts
mA
%FSS
Hz
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DSDX Series
Digital pressure transducers
TOTAL ACCURACY (-20 TO +105°C)
3.0
2.0
1.0
0
-1.0
-2.0
-3.0
-20
0
20
40
60
85
105
Total accuracy (%FSS)
Temperature (°C)
Specification notes:
1. If maximum burst pressure is exceeded, even momentarily, the package may leak or burst, or the pressure sensing die may
fracture.
2. Span is the algebraic difference between the output signal for the highest and lowest specified pressure.
3. Total accuracy is the combined error from offset and span calibration, linearity, pressure hysteresis, and temperature
effects. Linearity is the measured deviation based on a straight line. Hysteresis is the maximum output difference at
any point within the operating pressure range for increasing and decreasing pressure. Calibration errors include the
deviation of offset and full scale from nominal values.
4. Delay time between sampling and signal change at the output.
5. The smallest change in the output voltage, given any change in pressure.
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DSDX Series
Digital pressure transducers
INTRODUCTION
The DSDX is capable to generate a digital output signal. It
runs a cyclic program, which will store a corrected 12-bit
sensor value about every 10 ms within the output registers
of the internal ASIC. In order to use the pressure transducer
for digital signal readout, the device should be connected
to a bidirectional I²C-bus.
According to the I²C-bus communication specification, the
bus is controlled by a master device, which generates the
clock signal, controls the bus access and generates START
and STOP conditions. The DSDX is designed to work as a
slave, hence it will only respond to requests from a master
device.
The I²C-bus master-slave concept requires a unique
address for each device. The DSDX has a hard coded slave
address (1111000xb), therefore it is
not
possible to access
more than one DSDX on the same I²C-bus line.
STOP condition (P):
LOW to HIGH transition of SDA line while
clock (SCL) is HIGH determines STOP condition. STOP
conditions are always generated by the master. More than
one request for the current pressure value can be trans-
mitted without generation of intermediate STOP condition.
DATA valid (D):
State of data line represents valid data when,
after START condition, data line is stable for duration of
HIGH period of clock signal. Data on line must be
changed during LOW period of clock signal. There is
one clock pulse per bit of data.
Acknowledge (A):
Data is transferred in pieces of 8 bits
(1 byte) on serial bus, MSB first. After each byte receiving
device – whether master or slave – is obliged to pull
data line LOW as acknowledge for reception of data.
Master must generate an extra clock pulse for this pur-
pose. When acknowledge is missed, slave transmitter
becomes inactive. It is on master either to send last com-
mand again or to generate STOP condition in that case.
Slave address:
Each device connected to the bus has a
unique slave address. After generating a START con-
dition, the master has to transmit the slave address for
the DSDX with a READ command: $F1. The DSDX must
not be accessed with a WRITE command ($F0) as the
correct function of the device can not be guaranteed in
this case (note: a power-down power-up change will
force the sensor to use factory data again).
DATA operation:
The DSDX starts to send 2 data bytes containing
the current pressure value placed in the output registers.
DIGITAL I
2
C INTERFACE
The DSDX complies with the following protocol (FIGURE I):
Bus not busy:
During idle periods both data line (SDA) and
clock line (SCL) remain HIGH.
START condition (S):
HIGH to LOW transition of SDA line
while clock (SCL) is HIGH is interpreted as START con-
dition. START conditions are always generated by the
master. Each request for the current pressure value must
be initiated with a START.
SCL
SDA
START
condition
Data
valid
Data allowed
to change
STOP
condition
1
S Slave Address R/W A
Data Byte 1
A
Data Byte 2
S
Slave Address
Next command
P
Read out of pressure value
generated by master
generated by slave
S = START condition
A = Acknowledge
P = STOP condition
Data Byte 1 = High Byte (MSB first)
Data Byte 2 = Low Byte (LSB last)
FIGURE I:
I²C-BUS Protocol of DSDX
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