INTERSEMA MS5535-BM

MS5535B (RoHS*)
•
•
•
•
•
•
•
•
•
PRESSURE SENSOR MODULE
0 - 14 bar absolute pressure range
6 coefficients for software compensation stored
on-chip
Piezoresistive silicon micromachined sensor
Integrated miniature pressure sensor 9 x 9 mm
15 Bit ADC
3-wire serial interface
1 system clock line (32.768 kHz)
Low voltage and low power consumption
RoHS-compatible & Pb-free*
DESCRIPTION
The MS5535B is a SMD-hybrid device including a piezoresistive pressure sensor and an ADC-Interface IC. It
provides a 16 Bit data word from a pressure and temperature dependent voltage. Additionally the module
contains 6 readable coefficients for a highly accurate software calibration of the sensor. MS5535B is a low
power, low voltage device with automatic power down (ON/OFF) switching. A 3-wire interface is used for all
communications with a microcontroller.
Compared to the previous version (MS5535A) the temperature range has been improved (-40 to +125°C. Other
improvements concern the ESD sensitivity, current consumption and converter accuracy.
FEATURES
APPLICATIONS
• Supply voltage 2.2 V to 3.6 V
• Low supply current
• -40°C to +125°C operation temperature
• No external components required
• 15 Bit ADC resolution pressure measurement and
control systems
• Mobile water depth measurement systems
• Diving computers and divers watches
BLOCK DIAGRAM
VDD
MCLK
Input MUX
SENSOR
+IN
-IN
Digital
Interface
ADC
Sensor
Interface IC
SGND
DIN
DOUT
dig.
Filter
SCLK
Memory
(PROM)
64 bits
GND
Fig. 1: Block diagram 5535B.
*
The European RoHS directive 2002/95/EC (Restriction of the use of certain Hazardous Substances in electrical and electronic equipment)
bans the use of lead, mercury, cadmium, hexavalent chromium and polybrominated biphenyls (PBB) or polybrominated diphenyl ethers (PBDE).
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PIN CONFIGURATION
Fig. 2: Pin configuration of MS5535B.
Pin Name
Pin
Type
Function
GND
1
G
Ground
SCLK
2
I
Serial data clock
DOUT
3
O
Data output
DIN
4
I
Data input
MCLK
5
I
Master clock (32.768 kHz)
VDD
6
P
Positive supply voltage
PEN (1)
7
I
Programming enable
PV (1)
8
N
Negative programming voltage
NOTE
1) Pin 7 (PEN) and PIN 8 (PV) are only used by the manufacturer for calibration purposes and should not be
connected.
ABSOLUTE MAXIMUM RATINGS
Parameter
Supply voltage
Storage temperature
Overpressure
Symbol
VDD
TS
P
Conditions
o
Ta = 25 C
Min
Max
-0.3
-40
4
+125
o
Ta = 25 C
30
Unit
Notes
V
C
1
o
bar
NOTE
1) Storage and operation in an environment of dry and non-corrosive gases.
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RECOMMENDED OPERATING CONDITIONS
(Ta = 25°C, VDD = 3.0 V unless noted otherwise)
Parameter
Symbol
Conditions
Min.
Operating pressure range
p
0
Supply voltage
Supply current,
average (1)
during conversion (2)
standby (no conversion)
Current consumption into
MCLK (3)
Operating temperature
range
Conversion time
VDD
2.2
External clock signal (4)
Iavg
Isc
Iss
VDD = 3.0 V
3.0
4
1
MCLK = 32.768 kHz
T
tconv
-40
MCLK = 32.768 kHz
MCLK
Duty cycle of MCLK
Serial data clock
Typ.
SCLK
Max
Unit
14
bar abs.
3.6
V
0.1
µA
mA
µA
0.5
µA
+125
°C
35
ms
30.000
32.768
35.000
kHz
40/60
50/50
60/40
%
500
kHz
NOTES
1) Under the assumption of one conversion every second. Conversion means either a pressure or a temperature
measurement started by a command to the serial interface of MS5535B.
2) During conversion the sensor will be switched on and off in order to reduce power consumption; the total on
time within a conversion is about 2 ms.
3) This value can be reduced by switching off MCLK while MS5535B is in standby mode.
4) It is strongly recommended that a crystal oscillator be used because the device is sensitive to clock jitter. A
square-wave form of the clock signal is a must.
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ELECTRICAL CHARACTERISTICS
DIGITAL INPUTS
(T = -40°C .. 125°C, VDD = 2.2 V .. 3.6 V)
Parameter
Symbol
Conditions
Min
Typ
Max
Unit
Input High Voltage
VIH
80% VDD
100% VDD
V
Input Low Voltage
VIL
0% VDD
20% VDD
V
Signal Rise Time
tr
200
ns
Signal Fall Time
tf
200
ns
DIGITAL OUTPUTS
(T = -40°C .. 125°C, VDD = 2.2 V .. 3.6 V)
Parameter
Symbol
Conditions
Min
Output High Voltage
VOH
Isource = 0.6 mA
Output Low Voltage
VOL
Isink = 0.6 mA
Typ
Max
Unit
75% VDD
100% VDD
V
0% VDD
20% VDD
V
Signal Rise Time
tr
200
ns
Signal Fall Time
tf
200
ns
AD-CONVERTER
(T = -40°C .. 125°C, VDD = 2.2 V .. 3.6 V)
Parameter
Symbol
Conditions
Min
Resolution
INL
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Max
15
Linear Range
Conversion Time
Typ
0
MCLK = 32.768
kHz
Within linear range
-4
February 15th, 2006
Unit
Bit
40000
LSB
35
ms
+4
LSB
4
PRESSURE OUTPUT CHARACTERISTICS
With the calibration data stored in the interface IC of the MS5535B the following characteristics can be achieved:
(VDD = 3.0 V unless noted otherwise)
Parameter
Conditions
Min
p = 0 .. 5 bar
p = 0 .. 10 bar
p = 0 .. 14 bar
p = 0 .. 5 bar
p = 0 .. 10 bar
p = 0 .. 14 bar
p = 0 .. 5 bar
p = 0 .. 10 bar
p = 0 .. 14 bar
-25
-60
-150
-40
-60
-160
-80
-100
-200
Resolution
Absolute Pressure Accuracy
(Temperature range 0 .. +40°C)
Absolute Pressure Accuracy
(Temperature range -40 .. +85°C)
Absolute Pressure Accuracy
(Temperature range -40 .. +125°C)
Long-term Stability
Maximum Error over Supply Voltage
Typ
Max
1.2
6 months
VDD = 2.2 .. 3.6 V
+20
+20
+20
+100
+180
+200
+200
+300
+400
20
-20
+20
Unit
Notes
mbar
1
mbar
2
mbar
2
mbar
2
mbar
3
mbar/V
NOTES
1) A stable pressure reading of the given resolution requires taking the average of 2 to 4 subsequent pressure
values due to noise of the ADC.
2) Maximum error of pressure reading over the pressure range.
3) The long-term stability is measured with non-soldered devices.
TEMPERATURE OUTPUT CHARACTERISTICS
This temperature information is not required for most applications, but it is necessary to allow for temperature
compensation of the pressure output.
(VDD = 3.0 V unless noted otherwise)
Parameter
Conditions
Resolution
Accuracy
Maximum Error over Supply
Voltage
Min
Typ
Max
Unit
0.005
0.01
0.015
°C
T = 20°C
-0.8
0.8
°C
T = -40 .. +125°C
-2
+4
°C
VDD = 2.2 .. 3.6 V
-0.3
0.3
°C
Notes
1
NOTE
1) With the second-order temperature compensation as described in Section “FUNCTION". See next section for
typical operating curves.
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TYPICAL PERFORMANCE CURVES
ADC-value D1 vs Pressure (typical)
30000
ADC-value D1 (LSB)
25000
-40°C
25°C
125°C
20000
15000
10000
0
2000
4000
6000
8000
10000
12000
14000
Pressure (mbar)
ADC-value D2 vs Temperature (typical)
45000
40000
ADC-value D2 (LSB)
35000
30000
25000
20000
15000
-40
-20
0
20
40
60
80
100
120
Temperature (°C)
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Absolute Pressure Accuracy after Calibration
250
200
Pressure error (mbar)
150
125°C
100
85°C
60°C
25°C
0°C
50
-40°C
0
0
2000
4000
6000
8000
10000
12000
14000
12000
14000
-50
-100
Pressure (mbar)
Absolute Pressure Accuracy (2nd order) after Calibration
40
20
0
0
2000
4000
6000
8000
10000
Pressure error (mbar)
-20
125°C
-40
85°C
60°C
-60
25°C
0°C
-80
-40°C
-100
-120
-140
-160
Pressure (mbar)
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Pressure Error Accuracy vs temperature (typical)
120
100
Pressure error (mbar)
80
60
Pres. error 4bar (1st order)
40
Pres. error 4bar (2nd order)
20
0
-40
-20
0
20
40
60
80
100
120
-20
-40
Temperature (°C)
Temperature Error Accuracy vs temperature (typical)
15
Temperature error (°C)
10
Temperature error (standard
calculation)
Temperature error (with 2nd
order calculation)
5
0
-40
-20
0
20
40
60
80
100
120
-5
Temperature (°C)
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Pressure error vs supply voltage (typical)
8
6
4
Pressure error(mbar)
2
14000mba
r
6000mbar
0
2.2
2.4
2.6
2.8
3
3.2
3.4
3.6
3.4
3.6
1000mbar
-2
-4
-6
-8
-10
Voltage (V)
Temperature error (25°C) vs supply voltage (typical)
0.15
Temperature error (°C)
0.1
0.05
0
2.2
2.4
2.6
2.8
3
3.2
-0.05
-0.1
-0.15
Voltage (V)
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FUNCTION
GENERAL
The MS5535B consists of a piezoresistive sensor and a sensor interface IC. The main function of the MS5535B is
to convert the uncompensated analogue output voltage from the piezoresistive pressure sensor to a 16-Bit digital
value, as well as providing a 16-Bit digital value for the temperature of the sensor.
• measured pressure (16-Bit)
• measured temperature (16-Bit)
“D1”
“D2”
As the output voltage of a pressure sensor is strongly dependent on temperature and process tolerances, it is
necessary to compensate for these effects. This compensation procedure must be performed by software using
an external microcontroller.
D1
D2
Word1..4
Pressure
Calculation
in external
microcontroller
Temperature
Sensor
For both pressure and temperature measurement the same ADC is used (sigma delta converter):
• for the pressure measurement, the differential output voltage from the pressure sensor is converted
• for the temperature measurement, the sensor bridge resistor is sensed and converted
During both measurements the sensor will only be switched on for a very short time in order to reduce power
consumption. As both, the bridge bias and the reference voltage for the ADC are derived from VDD, the digital
output data is independent of the supply voltage.
FACTORY CALIBRATION
Every module is individually factory calibrated at two temperatures and two pressures. As a result, 6 coefficients
necessary to compensate for process variations and temperature variations are calculated and stored in the 64Bit PROM of each module. These 64-Bit (partitioned into four words of 16-Bit) must be read by the
microcontroller software and used in the program converting D1 and D2 into compensated pressure and
temperature values.
PRESSURE AND TEMPERATURE MEASUREMENT
The sequence of reading pressure and temperature as well as of performing the software compensation is
depicted in Fig. 3 and Fig. 5.
First the Word1 to Word4 have to be read through the serial interface. This can be done once after reset of the
microcontroller that interfaces to the MS5535B. Next the compensation coefficients C1 to C6 are extracted using
Bit-wise logical- and shift-operations (refer to Fig. 4 for the Bit-pattern of Word1 to Word4).
For the pressure measurement the microcontroller has to read the 16 Bit values for pressure (D1) and
temperature (D2) via the serial interface in a loop (for instance every second). Then, the compensated pressure
is calculated out of D1, D2 and C1 to C6 according to the algorithm in Fig. 3 (possibly using quadratic
temperature compensation according to Fig. 5). All calculations can be performed with signed 16-Bit variables.
Results of multiplications may be up to 32-Bit long (+sign). In the flow according to Fig. 3 each multiplication is
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followed by a division. This division can be performed by Bit-wise shifting (divisors are to the power of 2). It is
ensured that the results of these divisions are less than 65536 (16-Bit).
For the timing of signals to read out Word1 to Word4, D1, and D2 please refer to the paragraph “SERIAL
INTERFACE”.
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Basic equations:
System
initialisation
Start
Read calibration data (factory calibrated) from
PROM of MS5535B
Word1 = 18556
Word2 = 49183
Word3 = 22354
Word4 = 28083
Word1, Word2, Word3 and Word4 (4x16 Bit)
Convert calibration data into coefficients:
(see bit pattern of Word1-Word4)
C1: Pressure sensitivity
C2: Pressure offset
C3: Temperature coefficient of pressure sensitivity
C4: Temperature coefficient of pressure offset
C5: Reference temperature
C6: Temperature coefficient of the temperature
Pressure and temperature measurement
Example:
(13
(13
(10
(9
(12
(7
Bit)
Bit)
Bit)
Bit)
Bit)
Bit)
SENST1
OFFT1
TCS
TCO
T ref
TEMPSENS
C1 =
C2 =
C3 =
C4 =
C5 =
C6 =
2319
4864
349
219
2002
51
Read digital pressure value from MS5535B
D1 (16 Bit)
D1 = 17788
Read digital temperature value from MS5535B
D2 (16 Bit)
D2 = 26603
Calculate calibration temperature
UT1 = 8*C5 + 10000
Calculate actual temperature
Difference between actual temperature and reference
temperature:
dT = D2 - UT1
Actual temperature:
dT(D2) = D2 - Tref
dT
TEMP(D2) = 20 + dT(D2) * TEMPSENS
TEMP = 243
= 24.3°C
OFF(D2) = OFFT1 + TCO*dT(D2)
OFF
SENS(D2) = SENST1 + TCS * dT(D2)
SENS = 4198
11
TEMP = 200 + dT*(C6+100)/2 (0.1°C resolution)
= 587
Calculate temperature compensated pressure
Offset at actual temperature:
12
OFF = C2 + (C4 - 250)*dT/2 + 10000
Sensitivity at actual temperature:
= 14859
SENS = C1/2 + (C3 + 200) )*dT/213 + 3000
Temperature compensated pressure:
12
P = SENS * (D1 - OFF))/2 + 1000
P(D1,D2) = SENS(D2) * (D1 – OFF(D2))
P
= 4001
= 4001mbar
Display pressure and temperature value
Fig. 3: Flow chart for pressure and temperature reading and software compensation.
NOTES
1) Readings of D2 can be done less frequently, but the display will be less stable in this case.
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2) For a stable display of 0.1 mbar resolution, it is recommended to display the average of 8 subsequent
pressure values.
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C1 (13 Bit)
Word1
DB1
2
DB1
1
DB1
0
DB9
DB8
DB7
DB6
C2/I (3 Bit)
DB5
DB4
DB3
DB2
DB1
C2/II (10 Bit)
Word2
DB9
DB8
DB7
DB6
DB5
DB4
DB9
DB8
DB7
DB6
DB5
DB4
DB3
DB2
DB1
DB0
DB1
1
DB1
0
DB8
DB7
DB6
DB5
DB4
DB1
1
DB10
DB9
DB7
DB6
DB2
DB1
DB0
DB2
DB1
DB0
DB8
C5/II (6 Bit)
DB3
DB2
DB1
DB0
DB5
DB4
C4 (9 Bit)
Word4
DB1
2
C5/I (6 Bit)
C3 (10 Bit)
Word3
DB0
DB3
C6 (7 Bit)
DB3
DB2
DB1
DB0
DB6
DB5
DB4
DB3
Fig. 4: Arrangement (Bit-pattern) of calibration data in Word1 to Word4.
SECOND-ORDER TEMPERATURE COMPENSATION
In order to obtain best accuracy over the whole temperature range, it is recommended to compensate for the
non-linearity of the output of the temperature sensor. This can be achieved by correcting the calculated
temperature and pressure by a second order correction factor. The second-order factors are calculated as
follows:
dT ≥ 0
dT < 0
yes
yes
Low Temperatures
High Temperatures
dT2 = dT – (dT/128*dT/128)/2
dT2 = dT – (dT/128*dT/128)/8
Calculate temperature
TEMP = (200 + dT2*(C6+100)/2 11) (0.1°C)
Fig. 5: Flow chart for calculating the temperature and pressure to the optimum accuracy.
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SERIAL INTERFACE
The MS5535B communicates with microprocessors and other digital systems via a 3-wire synchronous serial
interface as shown in Fig. 1. The SCLK (Serial clock) signal initiates the communication and synchronises the data
transfer with each Bit being sampled by the MS5535B on the rising edge of SCLK and each Bit being sent by the
MS5535B on the rising edge of SCLK. The data should thus be sampled by the microcontroller on the falling edge
of SCLK and sent to the MS5535B with the falling edge of SCLK. The SCLK-signal is generated by the
microprocessor’s system. The digital data provided by the MS5535B on the DOUT pin is either the conversion
result or the software calibration data. In addition the signal DOUT (Data out) is also used to indicate the
conversion status (conversion-ready signal, see below). The selection of the output data is done by sending the
corresponding instruction on the pin DIN (Data input).
Following is a list of possible output data instructions:
•
•
•
•
•
•
•
Conversion start for pressure measurement and ADC-data-out
Conversion start for temperature measurement and ADC-data-out
Calibration data read-out sequence for Word1
Calibration data read-out sequence for Word2
Calibration data read-out sequence for Word3
Calibration data read-out sequence for Word4
RESET sequence
“D1”
“D2”
(Figure 6a)
(Figure 6b)
(Figure 6c)
(Figure 6d)
(Figure 6c)
(Figure 6d)
(Figure 6e)
Every communication starts with an instruction sequence at pin DIN. Fig. 6 shows the timing diagrams for the
MS5535B. The device does not need a ‘Chip select’ signal. Instead there is a START sequence (3-Bit high)
before each SETUP sequence and STOP sequence (3-Bit low) after each SETUP sequence. The SETUP
sequence consists in 4-Bit that select a reading of pressure, temperature or calibration data. In case of pressure(D1) or temperature- (D2) reading the module acknowledges the start of a conversion by a low to high transition
at pin DOUT during the last bit of the STOP sequence.
Two additional clocks at SCLK are required after the acknowledge signal. Then SCLK is to be held low by the
microcontroller until a high to low transition on DOUT indicates the end of the conversion.
This signal can be used to create an interrupt in the microcontroller. The microcontroller may now read out the 16Bit word by giving another 17 clocks on the SLCK pin. It is possible to interrupt the data READOUT sequence with
a hold of the SCLK signal. It is important to always read out the last conversion result before starting a
new conversion.
Conversion start for pressure measurement and ADC-data-out "D1":
end of conversion
st art of conversion
conversion
(33ms)
ADC-dat a outMS B
DB7 DB6 DB5 DB4 DB3 DB2 DB1
DIN
DOUT SCLK
The RESET sequence is special as its unique pattern is recognised by the module in any state. By consequence it
can be used to restart if synchronisation between the microcontroller and the MS5535B has been lost. This
sequence is 21-Bit long. The DOUT signal might change during that sequence (see Fig. 6e). It is recommended
to send the RESET sequence before each CONVERSION sequence to avoid hanging up the protocol
permanently in case of electrical interference.
ADC-dat a outLS B
DB0 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0
sequence: ST ART +P -measurement
Bit 0 Bit 1 Bit 2 Bit 3 Bit 4 Bit 5 Bit 6 Bit 7 Bit 8 Bit 9
St art -bit
Set up-bit s
St op-bit
Fig. 6a: D1 ACQUISITION sequence.
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end of conversion
conversion
(33ms)
st art of conversion
ADC-dat a outMS B
DB7 DB6 DB5 DB4 DB3 DB2 DB1
DIN
DOUT SCLK
Conversion start for temperature measurement and ADC-data-out "D2":
ADC-dat a outLS B
DB0 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0
sequence: ST ART +T -measurement
Bit 0 Bit 1 Bit 2 Bit 3 Bit 4 Bit 5 Bit 6 Bit 7 Bit 8 Bit 9
St art -bit
Set up-bit s
St op-bit
DIN
DOUT SCLK
Fig. 6b: D2 ACQUISITION sequence.
Calibration data read out sequence for word 1/ word 3:
coefficient -dat a outMS B
DB7 DB6 DB5 DB4 DB3 DB2 DB1
coefficient -dat a outLS B
DB0 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0
sequence: coefficient read + address
Bit 0 Bit 1 Bit 2 Bit 3 Bit 4 Bit 5 Bit 6 Bit 7 Bit 8 Bit 9Bit 10Bit 11
St art -bit
St op-bit
Set up-bit s
address word 1
address word 3
DIN
DOUT SCLK
Fig. 6c: Word1, Word3 READING sequence.
Calibration data read out sequence for word 2/ word 4:
coefficient -dat a outMS B
DB7 DB6 DB5 DB4 DB3 DB2 DB1
coefficient -dat a outLS B
DB0 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0
sequence: coefficient read + address
Bit 0 Bit 1 Bit 2 Bit 3 Bit 4 Bit 5 Bit 6 Bit 7 Bit 8 Bit 9 Bit 10Bit 11
St art -bit
Set up-bit s
St op-bit
address word 2
address word 4
Fig. 6d: W2, W4 READING sequence.
DIN
DOUT SCLK
RESET - sequence:
sequence: RESET
Bit 0 Bit 1 Bit 2 Bit 3 Bit 4 Bit 5 Bit 6 Bit 7 Bit 8 Bit 9 Bit 10Bit 11Bit 12Bit 13Bit 14Bit 15Bit 16Bit 17Bit 18Bit 19Bit 20
Fig. 6e: RESET sequence (21-Bit).
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APPLICATION INFORMATION
GENERAL
The advantage of combining a pressure sensor with a directly adapted integrated circuit is to save other external
components and to achieve a very low power consumption. The main application field for this system includes
portable devices with battery supply, but its high accuracy and resolution make it also suited for industrial and
automotive applications. The possibility to compensate the sensor with a software allows the user to adapt it to
his particular application. Communication between the MS5535B and the widely available microcontrollers is
realised over an easy-to-use 3-wire serial interface. Customers may select which microcontroller system to be
used, and there are no specific standard interface cells required, which may be of interest for specially designed
4 Bit-microcontroller applications.
CALIBRATION
The MS5535B is factory calibrated. The calibration data is stored inside the 64-Bit PROM memory.
SOLDERING
Please refer to the application note AN808 for all soldering issues.
HUMIDITY, WATER PROTECTION
The MS5535BM carries a metal protection cap filled with silicone gel for enhanced protection against humidity.
The properties of this gel ensure function of the sensor even when in direct water contact. This feature can be
useful for waterproof watches or other applications, where direct water contact cannot be avoided. Nevertheless
the user should avoid drying of hard materials like for example salt particles on the silicone gel surface. In this
case it is better to rinse with clean water afterwards. Special care has to be taken to not mechanically damage
the gel. Damaged gel could lead to air entrapment and consequently to unstable sensor signal, especially if the
damage is close to the sensor surface.
The metal protection cap is fabricated of special anticorrosive stainless steel in order to avoid any corrosive
battery effects inside the final product.
LIGHT SENSITIVITY
The MS5535B is sensitive to sunlight, especially to infrared light sources. This is due to the strong photo effect of
silicon. As the effect is reversible there will be no damage, but the user has to take care that in the final product
the sensor cannot be exposed to direct light during operation. This can be achieved for instance by placing
mechanical parts with holes in such that light cannot pass.
CONNECTION TO PCB
The package outline of the module allows the use of a flexible PCB to connect it. This can be important for
applications in watches and other special devices, and will also reduce mechanical stress on the device.
For applications subjected to mechanical shock, it is recommended to enhance the mechanical reliability of the
solder junctions by covering the rim or the corners of MS5535B'
s ceramic substrate with glue or Globtop-like
material.
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DECOUPLING CAPACITOR
Particular care must be taken when connecting the device to power supply. A 47 µF tantalum capacitor must be
placed as close as possible of the MS5535B'
s VDD pin. This capacitor will stabilise the power supply during data
conversion and thus, provide the highest possible accuracy.
APPLICATION EXAMPLE: DIVING COMPUTER SYSTEM USING MS5535B
MS5535B is a circuit that can be used in connection with a microcontroller in diving computer applications. It is
designed for low-voltage systems with a supply voltage of 3 V, particularly in battery applications. The MS5535B
is optimised for low current consumption as the AD-converter clock (MCLK) can use the 32.768 kHz frequency of
a standard watch crystal, which is supplied in most portable watch systems.
3V-Battery
LCD-Display
VDD
XTAL1
32.768 kHz
MS5535
VDD
47uF
Tantal
XTAL2
Keypad
MCLK
DIN
DOUT
SCLK
GND
4/8bit-Microcontroller
VSS
EEPROM
optional
Figure 7: Demonstration of MS5535B in a diving computer.
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DEVICE PACKAGE OUTLINES
Fig. 8: Device package outlines of MS5535BM.
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RECOMMENDED PAD LAYOUT
Pad layout for bottom side of MS5535B soldered onto printed circuit board
Pad layout for top side of MS5535B soldered onto printed circuit board
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ASSEMBLY
MECHANICAL STRESS
It is recommended to avoid mechanical stress on the PCB on which the sensor is mounted. The thickness of the
PCB should be not below 1.6 mm. A thicker PCB is more stiff creating less stress on the soldering contacts. For
applications where mechanical stress cannot be avoided (for example ultrasound welding of the case or thin
PCB’s in watches) please fix the sensor with drops of low stress epoxy (for example Hysol FP-4401) at the
corners of the sensor as shown below.
Fixing with Globtop
increases mechanical
stability
MOUNTING
The MS5535B can be placed with automatic Pick&Place equipment using vacuum nozzles. It will not be damaged
by the vacuum. Due to the low stress assembly the sensor does not show pressure hysteresis effects.
Special care has to be taken to not touch the protective gel of the sensor during the assembly.
The MS5535B can be mounted with the cap down or the cap looking upwards. In both cases it is important to
solder all contact pads. The Pins PEN and PV shall be left open or connected to VDD. Do not connect the Pins
PEN and PV to GND!
Solder at both sides to
increase mechanical
stability
Placement cap down
(hole in PCB to fit cap)
Placement cap up (rectangular
hole in PCB to fit Globtop)
SEALING WITH O-RING
In products like outdoor watches the electronics must be protected against direct water or humidity. For those
products the MS5535BM provides the possibility to seal with an O-ring. The protective cap of the MS5535BM is
made of special anticorrosive stainless steel with a polished surface. In addition to this the MS5535BM is filled
with silicone gel covering the sensor and the bonding wires. The O-ring (or O-rings) shall be placed at the outer
diameter of the metal cap. This method avoids mechanical stress because the sensor can move in vertical
direction.
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CLEANING
The MS5535B has been manufactured under cleanroom conditions. Each device has been inspected for the
homogeneity and the cleanness of the silicone gel. It is therefore recommended to assemble the sensor under
class 10’000 or better conditions. Should this not be possible, it is recommended to protect the sensor opening
during assembly from entering particles and dust. To avoid cleaning of the PCB, solder paste of type “no-clean”
shall be used. Cleaning might damage the sensor!
ESD PRECAUTIONS
The electrical contacts except programming pads are protected against ESD according to 2 kV HBM (human
body model). The PV programming pad is more sensitive due to the nature of the OTP programming cells that
store the calibration coefficients. The breakdown voltage of PV is 1 kV. It is therefore essential to ground
machines and personal properly during assembly and handling of the device. The MS5535B is shipped in
antistatic transport boxes. Any test adapters or production transport boxes used during the assembly of the
sensor shall be of an equivalent antistatic material.
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ORDERING INFORMATION
Product
Code
MS5535-BM
Product
Art.-Nr.
14 Pressure Sensor
Module with gel
325535001
Package
SMD hybrid with solder paste,
metal protection cap, silicon gel
sensor protection
Comments
standard version
FACTORY CONTACTS
Intersema Sensoric SA
Ch. Chapons-des-Prés 11
CH-2022 BEVAIX
SWITZERLAND
Tel. 032 847 9550
Tel. Int. +41 32 847 9550
Telefax +41 32 847 9569
e-mail:
http://www.intersema.ch
NOTICE
Intersema reserves the right to make changes to the products contained in this data sheet in order to improve the design or performance and to
supply the best possible products. Intersema assumes no responsibility for the use of any circuits shown in this data sheet, conveys no license
under any patent or other rights unless otherwise specified in this data sheet, and makes no claim that the circuits are free from patent
infringement. Applications for any devices shown in this data sheet are for illustration only and Intersema makes no claim or warranty that such
applications will be suitable for the use specified without further testing or modification.
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