MS5535C 14 bar Pressure Sensor Module
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• 0 – 14 bar absolute pressure range
• 6 coeffi cients for software c o m p ensation
stored on-chip
• Piezoresistive silicon micromachined sensor
• Integrated miniature pressure sensor 9 x 9 mm
• 16 Bit A DC
• 3-wire serial interface
• 1 system clock line (32.768 kHz)
• Low voltage and l o w po wer consumption
DESCRIPTION
The MS5535C 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. MS5535C 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 MS5 535 C is full y sof t war e compatible t o t he pr ev ious v ers ions ( MS 553 5A an d M S55 35 B) . C ompared to the
previous versions the ESD sensitivity has been improved to 4kV on all pins.
FEATURES APPLICATIONS
•
Supply voltage 2.2 V to 3.6 V
•
Mobile water depth measurement systems
•
Low supply current
•
Diving computers and divers watches
•
-40°C to +125°C operation temperature
•
No external components required
• 16 Bit ADC resolution pressure measurement
and control systems
BLOCK DIAGRAM
VDD
GND
MCLK
SCLK
DOUT
DIN
Input MUX
ADC
Digital
Interface
Memory
(PROM)
64 bits
SENSOR
SGND
+IN
-IN
dig.
Filter
Sensor
Interface IC
Fig. 1: B lock diagr am MS5535C
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PIN CONFIGURATION
Fig. 2: Pin configuration of MS5535C
Pin Name
Pin
Type
Function
GND
1
G
Ground
SCLK
2
I
Serial data cloc k
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 (PV) and Pin 8 (PEN) are only used by the manufacturer for calibration purposes and should not be
connected.
ABSOLUTE MAXIMUM RAT INGS
Parameter
Symbol
Conditions
Min
Max
Unit
Notes
Supply voltage
VDD
Ta = 25 °C
-0.3
4
V
Storage temperature
TS
-40
+125
°C
1
Overpressure
P
Ta = 25 °C
30
bar
2
NOTES
1) Storage and operation in an environment of dry and non-corrosive gases.
2) The MS5535-CM is qu alified ref erring to the ISO 6425 standard an d can withstan d an absolute press ure of
30 bar in salt water.
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RECOMMENDED O PERATING CONDITIONS
(Ta = 25 °C, VDD = 3.0 V unless noted otherwise)
Parameter
Symbol
Conditions
Min
Typ
Max
Unit
Operating pressure range
p
0
14
bar
Supply voltage
VDD
2.2
3.0
3.6
V
Supply current,
average (1)
during conversion (2)
standby (no conversion)
Iavg
Isc
Iss
VDD = 3.0 V
4
1
0.1
µA
mA
µA
Current consumption into MCLK
(3)
MCLK = 32.768 kHz 0.5 µA
Operating temperature range
T
-40
+125
°C
Conversion time
tconv
MCLK = 32.768 kHz
35
ms
External clo ck signal (4)
MCLK
30.000
32.768
35.000
kHz
Duty cycle of MCLK
40/60
50/50
60/40
%
Serial data cloc k
SCLK
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 MS5535C.
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 MS5535C 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 Voltag e
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
Typ
Max
Unit
Output High Voltage
V
OH
I
source
= 0.6 mA
80% V
DD
100% V
DD
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
(T = -40 °C .. 125 °C, VDD = 2.2 V .. 3.6 V)
Parameter
Symbol
Conditions
Min
Typ
Max
Unit
Resolution
16
Bit
Linear Range
4'000
40'000
LSB
Conversion Time
MCLK = 32.768 kHz
35
ms
INL
Within linear rang e
-5
+5
LSB
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PRESSURE OUTPUT CHARACTERISTICS
With the calibration data stored in the interface IC of the MS5535C, the following characteristics can be
achieved: (VDD = 3.0 V unless noted otherw ise)
Parameter
Conditions
Min
Typ
Max
Unit
Notes
Resolution
1.2
mbar
1
Absolute Pressure Accuracy
(Temperature range 0 .. +40 °C)
p = 0 .. 5 bar
p = 0 .. 10 bar
p = 0 .. 14 bar
-20
-40
-100
+20
+20
+20
mbar 2
Absolute Pressure Accuracy
(Temperature range -40 .. +85 °C)
p = 0 .. 5 bar
p = 0 .. 10 bar
p = 0 .. 14 bar
-40
-60
-160
+100
+180
+200
mbar 2
Absolute Pressure Accuracy
(Temperature range -40 ..+125°C)
p = 0 .. 5 bar
p = 0 .. 10 bar
p = 0 .. 14 bar
-80
-100
-300
+200
+200
+200
mbar 2
Long-term Stability
6 months
20
mbar
3
Maximum Error over Supply
Voltage
V
DD
= 2.2 .. 3.6 V
p = const.
-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) The long-term stability is measured with non-solder ed dev ices .
TEMPERATURE OUTPUT CHARACTERISTICS
This temperature information is not required for most applications, but it is necessary to allow for temperature
compensation of the output. (VDD = 3.0 V unless noted otherwise)
Parameter
Conditions
Min
Typ
Max
Unit
Notes
Resolution
0.005
0.01
0.015
°C
Accuracy
T = 20 °C
-0.8
0.8
°C
T = -40 .. +125°C
-4
+6
°C
1
Maximum Error over Supply
Voltage
VDD = 2 .2 .. 3.6 V -0.2 +0.2 °C
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)
10000
15000
20000
25000
30000
02000 4000 6000 8000 10000 12000 14000
Pressure (mbar)
ADC-value D1 (LS B)
-40°C
25°C
125°C
ADC-value D2 vs Temperature (typical)
15000
20000
25000
30000
35000
40000
45000
-40 -20 020 40 60 80 100 120
Temperature (°C)
ADC-value D2 (LSB)
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Absolute Pressure Accu racy after Cali bration, 1st order compensation
-100
-50
0
50
100
150
200
250
02000 4000 6000 8000 10000 12000 14000
Pressure (mbar)
Pressure error (mbar)
125°C
85°C
60°C
25°C
0°C
-40°C
Absolute Pressure Accu racy after Cali bration, 2nd order compensation
-250
-200
-150
-100
-50
0
50
100
02000 4000 6000 8000 10000 12000 14000
Pressure (mbar)
Pressure error (mbar)
125°C
85°C
60°C
25°C
0°C
-40°C
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Pressure Error Accuracy vs temperature (typical)
-50
-25
0
25
50
75
100
-40 -20 020 40 60 80 100 120
Temperature (°C)
Pressure error (mbar)
Pres. error 4bar (1st order)
Pres. error 4bar (2nd order)
Temperature Error Accuracy vs temperature (typical)
-5
0
5
10
15
-40 -20 020 40 60 80 100 120
Temperat ure (°C)
Temperature error (°C)
Temperature error (standard
calculation)
Temperature error (with 2nd
order calculati on)
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Pressure error vs supply voltage (typical)
-10
-8
-6
-4
-2
0
2
4
6
8
10
2.2 2.4 2.6 2.8 33.2 3.4 3.6
Voltage (V)
Pressure error (mb ar)
14000 mbar
6000 mbar
1000 mbar
Temperature error vs supply voltage (typical)
-0.15
-0.1
-0.05
0
0.05
0.1
0.15
2.2 2.4 2.6 2.8 33.2 3.4 3.6
Voltage (V)
Temperature error (°C)
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FUNCTION
GENERAL
The MS5535C consists of a piezo-resistive sensor and a sensor interface IC. The main function of the MS5535C
is to convert the uncompensated analogue output voltage from the piezo-resistive pressure sensor to a 16-bit
digital value, as well as pro vidin g a 16-bit digital value for the temperature of the sensor.
Measured pressure (16-bit) “D1”
Measured temperature (16-bit) “D2”
As the output voltage of a pressure sensor is strongly dependent on temperature and process tolerances, it is
necessar y to compens ate for thes e effect s. This com pensation proce dure mus t be perform ed by software us ing
an external microcontroller.
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 m odule is indi viduall y factor y calibra ted at two t em peratures and two pres sures . As a result, 6 c oeff icients
necessar y to com pens ate for proces s var iations and t em perature var iat ions ar e calc ulate d and stor ed in the 64-
bit 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 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 MS5535C. 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
temper ature (D2) via the ser ial interfac e in a loop (for instance ev ery second). T hen, the c ompensated pres sure
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 m ultiplicat ions m ay be u p to 32-b it lon g (+si gn). In the f low accor ding to F ig. 3 a divis ion f ollows e ach
Sensor
D1
D2
Word1..4
Calculation
in external
micro-
controller
Pressure
Temperature
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multiplication. 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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System
initialisation
Pressure and temperature measurement
Example:
Word1, Word2, Word3 and Word4 (4x16 Bit)
D1 = 17788
D2 = 26603
Start
Convert calibration data into coefficients:
(see bit pattern of Word1-Word4)
Read calibration data (factory calibrated) from
PROM of MS5535C
Read digital pressure value from MS5535C
D1 (16 Bit)
Read digital temperature value from MS5535C
Display pressure and temperature value
Basic equations:
Calculate calibration temperature
UT1 = 8*C5 + 10000
Calculate tem perat ur e co mpensated pressure
Difference between actual temperature and reference
temperature:
dT = D2 - UT1
Actual tem pe ra tur e:
TEMP = 200 + dT*(C6+100)/2
11
(0.1°C res ol uti on)
Calculate act ual tem perat ur e
D2 (16 Bit)
SENST1
OFFT1
TCS
TCO
T
ref
TEMPSENS
C1: Pressure sensitivity (13 Bit)
C2: Pressure offset (13 Bit)
C3: Temperature coefficient of pressure sensitivity (10 Bit)
C4: Temperature coefficient of pressure offset (9 Bit)
C5: Reference temperature (12 Bit)
C6: Temperature coefficient of the temperature (7 Bit)
(
Refer to application note AN519 for limits of coefficients and
calculated results)
Word1 = 18556
Word2 = 49183
Word3 = 22354
Word4 = 28083
C1 = 2319
C2 = 4864
C3 = 349
C4 = 219
C5 = 2002
C6 = 51
dT(D2) = D2 - T
ref
TEMP(D2) = 20 + dT(D2) * TEMPSENS
Offset at actual temperature:
OFF = C2 + (C4 - 250)*dT/2
12
+ 10000
Sensitivity at actual temperature:
SENS = C1/2 + (C3 + 200) )*dT/2
13
+ 3000
Temperature compensated pressure:
P = SENS * (D1 - OFF))/2
12
+ 1000
OFF(D2) = OFFT1 + TCO*dT(D2)
SENS (D2) = SENST1 + TCS * dT(D2)
P(D1,D2) = SENS(D2) * (D1 – OFF(D2))
dT = 587
TEMP = 243
= 24.3°C
OFF = 14859
SENS = 4198
P = 4001
= 4001mbar
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 1 mbar resolution, it is recommended to display the average of 8 subsequent
pressure values.
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C1 (13 Bit)
C2/I (3 Bit)
Word 1 DB12 DB11 DB10 DB9 DB8 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 DB12 DB11 DB10
C2/II (10 Bit)
C5/I (6 Bit)
Word 2 DB9 DB8 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 DB11 DB10 DB9 DB8 DB7 DB6
C3 (10 Bit)
C5/II (6 Bit)
Word 3 DB9 DB8 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 DB5 DB4 DB3 DB2 DB1 DB0
C4 (9 Bit)
C6 (7 Bit)
Word 4 DB8 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB1 DB6 DB5 DB4 DB3 DB2 DB1 DB0
Fig. 4: Arrangement (Bit-pattern) of calibrat ion data in Word1 t o Word4
SECOND-ORDER TEMPERATURE COMPENSATION
In order to obtain full temperature accuracy over the whole temperature range, it is recommended to
compens ate f or the n on-linearity of the o utp ut of the tem per atur e sens or . T his can be ac hi ev ed by correcti ng t he
calculated temperature and pressure by a second order correction factor. The second-order factors are
calculated as follows:
High Temperatures
dT2 = dT – (dT/128*dT/128)/8
dT < 0
yes
Calculate temperature
TEMP = (200 + dT2*(C6+100)/2
11
) (0.1°C)
Low Temperatures
dT2 = dT – (dT/128*dT/128)/2
dT ≥ 0
yes
Fig. 5: Flow chart for calculating the temperature and pressure to the optimum accuracy.
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SERIAL INTERFACE
The MS5535C 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 synchronizes the
data trans fer with each bit bei ng sampled b y the MS5535C on the r ising edge of SCL K and each bit bein g sent
by the MS5535C on the rising edge of SCLK. The data should thus be sampled by the microcontroller on the
falling edg e of SCLK and s ent to the MS5535C with th e fallin g edge of SCL K. The SCLK -signal is gen erate d b y
the microprocessor’s system. The digital data provided by the MS5535C 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 t he conversi on status (conversion-r eady signa l, see belo w). The selec tion 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 “D1” (Figure 6a)
• Conversion start for temperature measurement and ADC-data-out “D2” (Figure 6b)
• Calibration data read-out sequence for Word1 (Figure 6c)
• Calibrat ion dat a read-out sequence for Word2 (Figure 6d)
• Calibration data read-out sequence for Word3 (Figure 6c)
• Calibration data read-out sequence for Word4 (Figure 6d)
• RESET sequence (Figure 6e)
Every communication starts with an instruction sequence at pin DIN. Fig. 6 shows the timing diagrams for the
MS5535C. 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 temperat ure- (D2) r ead ing t h e module ack no wledges t he s t art o f a conversi on by a low t o h igh
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 ma y now read out the
16 bit word b y giving a not h er 17 cloc ks on the SLCK pin. It is poss ib le to i nterr up t the dat a R EAD OUT sequence
with a hol d of the SCLK s ignal. It is important to always read out the last conversion result before s tarting
a new conversion.
The RESET sequence is special as the module in any state recognizes its unique pattern. By consequence, it
can be used to restart if synchronization between the microcontroller and the MS5535C has been lost. This
sequence is 21-bit long. T he DO UT signal m ight change dur ing that seq uence (s ee Fig. 6e). It is rec ommended
to send the RESET sequence before each CONVERSION sequence to avoid hanging up the protocol
permanently in case of electrical interference.
sequence: START+P-measurement
SCLKDOUTDIN
Bit7
Conversion start for pressure measurement and ADC-data-out "D1":
end of co nve rsion
Bit6Bit5Bit4Bit3Bit2Bit1Bit0
conversion
(33ms)
DB7
ADC-data ou t MSB ADC-data o u t LSB
Bit8 Bit9
Start-bit Stop-bit
DB6 DB5 DB4 DB3 DB2 DB1 DB0 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0
start of conversion
Setup-bits
Fig. 6a: D1 ACQUISITION sequence
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sequence: START+T-measurement
SCLK
DOUT
DIN
Bit7
Conversion start for temperature measurement and ADC-data-out "D2":
end of co nve rsion
Bit6Bit5Bit4Bit3Bit2Bit1Bit0
conversion
(33ms)
Bit8 Bit9
Start-bit Stop-bitSetup-bits
start of conversion
DB7
ADC-data ou t MSB ADC-data o u t LSB
DB6 DB5 DB4 DB3 DB2 DB1 DB0 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0
Fig. 6b: D2 ACQUISITION sequence
sequence: coefficient r ead + ad dr ess
SCLKDOUTDIN
Bit7
Calibration data read out sequence for word 1/ word 3:
Bit6Bit5Bit4Bit3Bit2Bit1Bit0
DB7
coefficient-data o ut MSB coefficient-data out LSB
Bit8 Bit9
Start-bit Stop-bit
DB6 DB5 DB4 DB3 DB2 DB1 DB0 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0
Bit10 Bit11
address word 1
address word 3
Setup-bits
Fig. 6c: Word1, Word3 READING sequence
address word 2
address word 4
sequence: coefficient r ead + ad dr ess
SCLK
DOUT
DIN
Bit7
Calibration data read out sequence for word 2/ word 4:
Bit6Bit5Bit4Bit3Bit2Bit1Bit0
DB7
coefficient-data o ut MSB coefficient-data out LSB
Bit8 Bit9
Start-bit Stop-bit
DB6 DB5 DB4 DB3 DB2 DB1 DB0 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0
Bit10 Bit11
Setup-bits
Fig. 6d: W2, W4 REA DING sequence
sequence: RESET
SCLK
DOUT
DIN
Bit7
RESET - sequence:
Bit6Bit5Bit4Bit3Bit2Bit1Bit0 Bit8 Bit9 Bit10 Bit11Bit12 Bit13 Bit14 Bit15 Bit16 Bit17 Bit18 Bit19 Bit20
Fig. 6e: RESET sequence (21 bit)
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APP LICATION INFORMATION
GENERAL
The advant age f or this c om binat ion of a sensor with a dir ectly adapted int egrated circ uit is to s ave o ther ex ternal
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
automot ive ap pl icati ons . The possib ility to compens ate the s ens or with soft ware a l lo ws th e us er to a dap t it t o his
particular application. Communication between the MS5535C 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 ther e are no spe cif ic standard inter fac e cells required, which m a y be of interest f or speciall y designed
4 Bit-microcontroller applications.
CALIBRATION
The MS5535C 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 MS5535CM carries a metal protection cap filled with silicone gel for enhanc ed protection against humidit y.
The properties of this gel ensure function of the sensor even when in direct water contact. This feature can be
useful f or waterpro of watch es or other appl ications , wher e direct water contac t ca nnot be a voided . Neverthe les s
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 mechanicall y damage
the gel. D am aged gel coul d lead to air entr apment an d consequen tly to unstable sensor sig nal, espec ially 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 MS5535C is se nsitive to sun light, especi ally to infrar ed light sources . This is due t o the strong p hoto effec t
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 applicat ions subjected to m echanical shock, it is recommended to enhance the mechanical reliabilit y of the
solder junctions by covering the rim or the corners of MS5535C's ceramic substrate with glue or Globtop-like
material.
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DECOUPLING CAPACITOR
Particular c ar e must be tak en wh en connecting the de vice t o p o wer sup ply. A 47 µF tanta lum capacitor must be
placed as close as possible of the MS5535C's VDD pin. This capacitor will stabilize the power supply during
data convers ion and thus, prov ide the hi ghest pos s ib le acc uracy.
APPLI CATION EXAM PLE: DIVING COM PUT ER USING MS5535C
MS5535C is a cir cuit that c an be used in c onnection with a microcont roller in diving com puter app lications. It is
designed for low-voltage s ystem s with a sup ply vo ltage of 3V, p articu larl y in batt er y applicati ons. T he MS5535C
is optim ised for low current consumption as the AD -converter clock (MCLK) can use the 32.768 kH z frequency
of a standard watch crystal, which is supplied in most portable watch systems.
4/8bit-Microcontroller
LCD-Display
EEPROM
Keypad
MS5535C
SCLK
DIN
DOUT
MCLK
XTAL1
XTAL2
32.768 kHz
optional
VDD
GND
VDD
GND
3V-Battery
47µF
Tantal
Figure 7: Demonstration of MS5535C in a diving computer.
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DEVICE PACKAGE OUTLINES
Fig. 8: Device package outlines of MS5535-CM
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RECOMMENDED PAD LAYOUT
Pad layout for bottom side of MS5535C soldered onto printed circuit board.
Fig. 9: Layout for bott om sid e
Pad layout for top side of MS5535C soldered onto printed circuit board.
Fig. 10: Layout for topside
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ASSEMBLY
M ECHANICAL ST RES S
It is recom mended to avoid m ec hanical st res s on t he PC B on which the sensor is mounted. T he th ic kness 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.
MOUNTING
The MS5535C 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 MS5535C can be mounted with the cap down or the cap looking upwards. In both cases it is important to
solder al l c o ntact pads. The P ins P EN and P V s h al l b e l ef t op en or con nec ted to VDD. Do not connect the Pins
PEN and PV to GND!
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 M S5535-CM p rovi des t he p oss ibi lit y to se al with an O -ring . The protec tive cap of t he M S5535CM is
made of special anticorrosive stainless steel with a po lished surface. In addition to this the MS5535CM is filled
with silico ne gel cover ing the sens or and the b onding wires . The O -ring (or O-rings ) shall be plac ed 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 MS5535C has been manufactured under cleanroom conditions. Each device has been inspected for the
homogeneity and the cleanness of the silicone gel. It is therefore recomm ended 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 ass embl y from entering p articles and d ust. T o avoid cleani ng of the PCB , solder pas te 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
essentia l to ground machines and p er s onal pr o per l y d ur ing ass embly and han dl in g of the device. T he MS5535C
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.
ORDERING INFORMATION
Product Code
Product
Art. No
Package
Comments
MS5535-CM 14 bar Pressure
Sensor Module with
gel 325535009
SMD hybrid with solder paste,
metal protection cap,
silicone gel sensor protection
Standard version
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ASIA
Measurement Specialties
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The information in this sheet has been carefull y reviewed and is believed to be accurate; however, no responsibility is assumed for
inaccuracies. Furtherm ore, this inform ation does not convey to the purchaser of such devices any license under the patent rights to the
manufacturer. Measurement Specialties, Inc. reserves the right to make changes without further notice to any product herein. Measurement
Specialti es, Inc. makes no warranty, represent ation or guarant ee regarding the sui t abili t y of its product for any particular purpose, nor does
Measurement Specialti es, Inc. assume any liability arising out of the applic ation or use of any product or circuit and specific al l y disclaims
any and all liabilit y, includi ng without limitation consequential or incidental damages. Typical parameters can and do vary in different
applicat i ons. All operat i ng parameters must be validated for each customer application by customer’s technical experts. Meas urem ent
Specialti es, Inc. does not convey any license under its patent rights nor the rights of others.
