Intersema MS5534C Barometer module Datasheet

MS5534C (RoHS*)
BAROMETER MODULE
• 10 - 1100 mbar absolute pressure range
• 6 coefficients for software compensation stored
on-chip
• Piezoresistive silicon micromachined sensor
• Integrated miniature pressure sensor 9 x 9 mm
• 16 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 MS5534C 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. MS5534C 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.
The MS5534C is fully software compatible to the previous versions (MS5534A and MS5534B). Compared to the
previous versions the ESD sensitivity level has been improved to 4kV on all pins.
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
• Mobile altimeter / barometer systems
• Weather control systems
• Adventure or multi-mode watches
• GPS receivers
BLOCK DIAGRAM
VDD
MCLK
Input MUX
SENSOR
Digital
Interface
+IN
-IN
ADC
Sensor
Interface IC
DIN
DOUT
dig.
Filter
SCLK
Memory
(PROM)
64 bits
SGND
GND
Fig. 1: Block diagram MS5534C.
*
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 MS5534CM.
Pin Name
Pin
Type
Function
GND
SCLK
DOUT
DIN
MCLK
VDD
PEN (1)
PV (1)
1
2
3
4
5
6
7
8
G
I
O
I
I
P
I
N
Ground
Serial data clock
Data output
Data input
Master clock (32.768 kHz)
Positive supply voltage
Programming enable
Negative programming voltage
NOTES
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
Symbol
VDD
TS
Conditions
o
Ta = 25 C
o
Overpressure
P
MS5534-CP, Ta = 25 C
o
MS5534-CM, Ta = 25 C
Min
Max
Unit
-0.3
-40
4
+125
5
10
V
C
bar
bar
o
Notes
1
2
NOTES
1) Storage and operation in an environment of dry and non-corrosive gases.
2) The MS5534CM is qualified referring to the ISO Standard 2281 and can withstand an absolute pressure of
11 bar in salt water or 100 m water respectively.
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RECOMMENDED OPERATING CONDITIONS
Parameter
Operating pressure range
Supply voltage
Supply current,
average (1)
during conversion (2)
standby (no conversion)
Current consumption into
MCLK (3)
Operating temperature
range
Conversion time
External clock signal (4)
Symbol
(Ta = 25°C, VDD = 3.0 V unless noted otherwise)
Conditions
Min.
Typ.
Max
Unit
p
10
VDD
2.2
Iavg
Isc
Iss
VDD = 3.0 V
tconv
MCLK = 32.768 kHz
MCLK
SCLK
0.1
µA
mA
µA
0.5
µA
+125
°C
35
ms
4
1
-40
Duty cycle of MCLK
Serial data clock
3.0
MCLK = 32.768 kHz
T
3.6
mbar
abs.
V
1100
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 MS5534C.
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 MS5534C 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
Parameter
Symbol
Conditions
Min
(T = -40°C .. 125°C, VDD = 2.2 V .. 3.6 V)
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
Parameter
(T = -40°C .. 125°C, VDD = 2.2 V .. 3.6 V)
Typ
Max
Unit
Symbol
Conditions
Min
Output High Voltage
VOH
Isource = 0.6 mA
80% VDD
100% VDD
V
Output Low Voltage
VOL
Isink = 0.6 mA
0% VDD
20% VDD
V
Signal Rise Time
tr
200
ns
Signal Fall Time
tf
200
ns
AD-CONVERTER
Parameter
Symbol
Conditions
Min
Resolution
16
Linear Range
Conversion Time
INL
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(T = -40°C .. 125°C, VDD = 2.2 V .. 3.6 V)
Typ
Max
Unit
4000
MCLK = 32.768
kHz
Within linear
range
-5
June 16th, 2008
Bit
40000
LSB
35
ms
+5
LSB
4
PRESSURE OUTPUT CHARACTERISTICS
With the calibration data stored in the interface IC of the MS5534C the following characteristics can be achieved:
Parameter
Conditions
Min
Resolution
Absolute Pressure Accuracy
Relative Pressure Accuracy
Relative Pressure Error over
Temperature
Long-term Stability
Maximum Error over Supply
Voltage
(VDD = 3.0 V unless noted otherwise)
Typ
Max
Unit
Notes
0.1
p = 750 .. 1100 mbar
Ta = 25°C
p = 750 .. 1100 mbar
Ta = 25°C
T = 0 .. +85°C
p = 300 .. 1000 mbar
T = -40 .. +125°C
p = 300 .. 1000 mbar
12 months
VDD = 2.2 .. 3.6 V
p = const.
mbar
1
-1.5
+1.5
mbar
2
-0.5
+0.5
mbar
3
-2
+2
mbar
4
-8
+5
mbar
4
mbar
5
-1
-1.6
+1.6
mbar
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) Maximum error of pressure reading over the pressure range after offset adjustment at one pressure point.
4) With the second-order temperature compensation as described in Section “FUNCTION". See next section
for typical operating curves.
5) 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
Min
Typ
Max
Unit
Notes
Resolution
0.005
T = 20°C
Accuracy
Maximum Error over Supply
Voltage
-0.8
0.01
0.015
°C
0.8
°C
T = -20 .. +85°C
-2
+2
°C
1
T = -40 .. +125°C
-6
+3
°C
1
VDD = 2.2 .. 3.6 V
-0.2
+ 0.2
°C
2
NOTES
1) With the second-order temperature compensation as described in Section “FUNCTION". See next section
for typical operating curves.
2) At Ta = 25 °C
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TYPICAL PERFORMANCE CURVES
ADC-value D1 vs Pressure (typical)
22000
20000
18000
ADC-value D1 (LSB)
16000
-40°C
25°C
125°C
14000
12000
10000
8000
6000
0
100
200
300
400
500
600
700
800
900
1000
1100
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)
Absolute Pressure Accuracy after Calibration, 2nd order compensation
8
6
Pressure error (mbar)
4
2
125°C
85°C
60°C
0
25°C
0°C
-40°C
-2
-4
-6
-8
0
100
200
300
400
500
600
700
800
900
1000
1100
Pressure (mbar)
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Temperature Error Accuracy vs temperature (typical)
15
Temperature error (°C)
10
Temperature error (standard
calculation)
Temperature error (with 2nd
order calculation)
5
0
-5
-40
-20
0
20
40
60
80
100
120
Temperature (°C)
Pressure Error Accuracy vs temperature (typical)
18
16
14
12
Pressure error (mbar)
10
8
Perror(1000,1st order)
Perror(1000,2nd order)
6
Perror(800,1st order)
4
Perror(800,2nd order)
Perror(300,1st order)
2
Perror(300,2nd order)
0
-2
-4
-6
-8
-40
-20
0
20
40
60
80
100
120
Temperature (°C)
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Pressure error vs supply voltage (typical)
1
0.8
0.6
Pressure error (mbar)
0.4
0.2
0
2.2
2.4
2.6
2.8
3
3.2
3.4
3.6
3.4
3.6
1000mbar
800mbar
300mbar
-0.2
-0.4
-0.6
-0.8
-1
Voltage (V)
Temperature error 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 MS5534C consists of a piezoresistive sensor and a sensor interface IC. The main function of the MS5534C
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
Pressure
D2
Word1..4
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 MS5534C. 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
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
Example:
Read calibration data (factory calibrated) from
PROM of MS5534C
Word1 = 50426
Word2 = 9504
Word3 = 48029
Word4 = 55028
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
(15 Bit)
(12 Bit)
(10 Bit)
(10 Bit)
(11 Bit)
(6 Bit)
SENST1
OFFT1
TCS
TCO
Tref
TEMPSENS
C1 = 25213
C2 = 1908
C3 = 859
C4 = 750
C5 = 148
C6 =
32
(Refer to application note AN509 for limits of coefficients and
Pressure and temperature measurement
calculated results)
Read digital pressure value from MS5534C
D1 (16 Bit)
D1 = 17000
Read digital temperature value from MS5534C
D2 (16 Bit)
D2 = 22500
Calculate calibration temperature
UT1 = 8*C5+20224
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 = 287
= 28.7 °C
OFF(D2) = OFFT1+TCO*dT(D2)
OFF
SENS(D2) = SENST1+TCS*dT(D2)
SENS = 50705
10
TEMP = 200 + dT*(C6+50)/2 (0.1°C resolution)
= 1092
Calculate temperature compensated pressure
Offset at actual temperature:
OFF = C2*4 + ((C4-512)*dT)/212
Sensitivity at actual temperature:
= 7695
SENS = C1 + (C3*dT)/210 + 24576
X = (SENS * (D1-7168))/214 - OFF
Temperature compensated pressure:
P = X*10/25 + 250*10
(0.1mbar resolution)
X
= 22732
P
= 9603
= 960.3 mbar
P(D1,D2) = D1*SENS(D2)-OFF(D2)
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.
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 (15 Bit)
C5/I
1 Bit
Word1
DB14
DB13
DB12
DB11
DB10
DB9
DB8
DB7
DB6
DB5
DB4
DB3
C5/II (10 Bit)
Word2
DB9
DB8
DB7
DB6
DB5
DB4
DB9
DB8
DB7
DB6
DB5
DB4
DB3
DB2
DB1
DB0
DB5
DB4
DB9
DB8
DB7
DB6
DB5
DB4
DB0
DB10
DB3
DB2
DB1
DB0
DB7
DB6
DB1
DB0
C2/I (6 Bit)
DB3
DB2
DB1
DB0
DB11
DB10
C3 (10 Bit)
Word4
DB1
C6 (6 Bit)
C4 (10 Bit)
Word3
DB2
DB9
DB8
C2/II (6-Bit)
DB3
DB2
DB1
DB0
DB5
DB4
DB3
DB2
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:
TEMP < 200
TEMP > 450
200 ≤ TEMP ≤ 450
yes
yes
yes
No correction
Low Temperatures
High Temperatures
T2 = 11*(C6+24)*(200 - TEMP)*(200 – TEMP) / 220
T2 = 0
T2 = 3*(C6+24)*(450 - TEMP)*(450 – TEMP) / 220
P2 = 3 *T2 * (P - 3500)/214
P2 = 0
P2 = T2 * (P - 10000)/213
Calculate pressure and temperature
TEMP = TEMP – T2
P = P – P2
Fig. 5: Flow chart for calculating the temperature and pressure to the optimum accuracy.
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SERIAL INTERFACE
The MS5534C 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 MS5534C on the rising edge of SCLK and each Bit being sent
by the MS5534C 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 MS5534C with the falling edge of SCLK. The SCLK-signal is generated by
the microprocessor’s system. The digital data provided by the MS5534C on the DOUT pin is either the
conversion result or the software calibration data. In addition the signal DOUT (Data output) 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
MS5534C. 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.
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
16-Bit 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
start of conversion
conversion
(33ms)
ADC-data out MSB
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 MS5534C 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 first CONVERSION sequence to avoid hanging up the protocol permanently
in case of electrical interference.
ADC-data out LSB
DB0 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0
sequence: START+P-measurement
Bit0 Bit1 Bit2 Bit3 Bit4 Bit5 Bit6 Bit7 Bit8 Bit9
Start-bit
Setup-bits
Stop-bit
Fig. 6a: D1 ACQUISITION sequence.
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end of conversion
conversion
(33ms)
start of conversion
ADC-data out MSB
DB7 DB6 DB5 DB4 DB3 DB2 DB1
DIN
DOUT SCLK
Conversion start for temperature measurement and ADC-data-out "D2":
ADC-data out LSB
DB0 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0
sequence: START+T-measurement
Bit0 Bit1 Bit2 Bit3 Bit4 Bit5 Bit6 Bit7 Bit8 Bit9
Start-bit
Setup-bits
Stop-bit
DIN
DOUT SCLK
Fig. 6b: D2 ACQUISITION sequence.
Calibration data read out sequence for word 1/ word 3:
coefficient-data out MSB
DB7 DB6 DB5 DB4 DB3 DB2 DB1
coefficient-data out LSB
DB0 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0
sequence: coefficient read + address
Bit0 Bit1 Bit2
Bit3 Bit4 Bit5 Bit6 Bit7 Bit8 Bit9 Bit10 Bit11
Setup-bits
Start-bit
Stop-bit
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-data out MSB
DB7 DB6 DB5 DB4 DB3 DB2 DB1
coefficient-data out LSB
DB0 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0
sequence: coefficient read + address
Bit0 Bit1 Bit2 Bit3 Bit4 Bit5 Bit6 Bit7 Bit8 Bit9 Bit10 Bit11
Setup-bits
Start-bit
Stop-bit
address word 2
address word 4
RESET - sequence:
DIN
DOUT SCLK
Fig. 6d: W2, W4 READING sequence.
sequence: RESET
Bit0 Bit1 Bit2 Bit3 Bit4 Bit5 Bit6 Bit7 Bit8 Bit9 Bit10 Bit11Bit12 Bit13 Bit14 Bit15
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 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 software allows the user to adapt it to his
particular application. Communication between the MS5534C 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 Bitmicrocontroller applications.
CALIBRATION
The MS5534C 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 version MS5534CM 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. The MS5534CM was qualified referring to the ISO Standard 2281 and
can withstand a pressure of 11 bar in salt water. The concentration of the sea water used for the qualification is
41 g of see salt for 1 litre of DI water.
For underwater operations as specified in ISO Standard 2281 it is important to seal the sensor with a rubber Oring around the metal cap. Any salt water coming to the contact side (ceramic and pads) of the sensor could lead
to permanent damage. Especially for "water-resistant 100 m" watches it is recommended to provide a stable
mechanical pusher from the backside of the sensor. Otherwise the overpressure might push the sensor
backwards and even bend the electronic board on which the sensor is mounted.
LIGHT SENSITIVITY
The MS5534C 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 MS5534C'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 MS5534C's VDD pin. This capacitor will stabilise the power supply during data
conversion and thus, provide the highest possible accuracy.
APPLICATION EXAMPLE: ALTIMETER SYSTEM USING MS5534C
MS5534C is a circuit that can be used in connection with a microcontroller in mobile altimeter applications. It is
designed for low-voltage systems with a supply voltage of 3 V, particularly in battery applications. The MS5534C
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.
For applications in altimeter systems Intersema can deliver a simple formula to calculate the altitude, based on a
linear interpolation, where the number of interpolation points influences the accuracy of the formula.
3V-Battery
LCD-Display
VDD
XTAL1
32.768 kHz
MS5534
VDD
47µF
Tantal
XTAL2
Keypad
MCLK
DIN
DOUT
SCLK
GND
4/8bit-Microcontroller
GND
EEPROM
optional
Figure 7: Demonstration of MS5534C in a mobile altimeter.
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DEVICE PACKAGE OUTLINES
Fig. 8: Device package outlines of MS5534CP.
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DEVICE PACKAGE OUTLINES
Fig. 9: Device package outlines of MS5534CM.
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RECOMMENDED PAD LAYOUT
Pad layout for bottom side of MS5534C soldered onto printed circuit board
Fig. 10: Layout for bottom side
Pad layout for top side of MS5534C soldered onto printed circuit board
Fig. 11: Layout for top side
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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 not be below 1.6 mm. A thicker PCB is stiffer 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 MS5534C 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 MS5534C 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
SEALING WITH O-RING
In products like outdoor watches the electronics must be protected against direct water or humidity. For those
products the MS5534CM provides the possibility to seal with an O-ring. The protective cap of the MS5534CM is
made of special anticorrosive stainless steel with a polished surface. In addition to this the MS5534CM 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 MS5534C 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 contact pads are protected against ESD up to 4 kV HBM (human body model). It is therefore
essential to ground machines and personal properly during assembly and handling of the device. The MS5534C
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
Product
Art.-Nr.
Package
Comments
MS5534-CP
Barometer Module
with plastic cap
325534008
SMD hybrid with solder paste,
plastic protection cap
Standard version
MS5534-CM
Barometer Module
with metal cap
325534009
SMD hybrid with solder paste,
metal protection cap, silicon
gel sensor protection
Recommended
for outdoor products
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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