MS5541-CM - Measurement Specialties

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MS5541C (RoHS

)

MINIATURE 14 bar MODULE

• 0 - 14 bar absolute pressure range

• 6 coefficients for a software compensation stored

on-chip

• Piezoresistive silicon micromachined sensor

• Integrated pressure sensor 6.2x6.4 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 MS5541C is the miniature version of MS5535C pressure sensor module. It contains a precision

piezoresistive pressure sensor and an improved version of the 15 Bit Micropower Sensor interface IC known

from the MS5535C. Compared to the previous version the ESD sensitivity has been improved to 4kV on all pins.

In addition to this the MS5541C is from its outer dimensions compatible to the MS54xx series of pressure

sensors. It uses an antimagnetic polished stainless steel ring for sealing with O-ring. The sensor provides 15 Bit

pressure and temperature data via a 3 wire serial interface that can be easily interfaced with 4 Bit low power

microcontrollers. 64 Bit of factory programmed PROM provides calibration data for a highly accurate pressure

and temperature calculation. The MS5541C is fully software compatible to the MS5535C and previous versions

of MS5541.

FEATURES APPLICATIONS

• Resolution 1.2 mbar • Diving computers and divers watches

• Supply voltage 2.2 V to 3.6 V • Mobile water depth measurement systems

• Operating current < 5uA

• Standby current < 0.1uA

• -40°C to +85°C

• No external components required

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 Block Diagram MS5541C

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 MS5541C

Pin Name Pin Type Function

SCLK 1 I Serial data clock

VSS 2 G Ground

PV (1) 3 N Negative programming voltage (do not connect)

PEN (1) 4 I Programming enable (do not connect)

VDD 5 P Positive supply voltage

MCLK 6 I Master clock (32.768kHz)

DIN 7 I Serial data input

DOUT 8 O Serial data output

NOTE

1) Pins 3 (PV) and 4 (PEN) are only used by the manufacturer for calibration purposes and should not be

connected.

ABSOLUTE MAXIMUM RATINGS

Parameter Symbol Conditions Min Max Unit Notes

Supply Voltage VDD Ta = 25

C -0.3 4 V

Storage Temperature T

-40 +85

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 MS5541CM is qualified referring to the ISO 6425 standard and can withstand an absolute pressure of

30 bar in salt water.

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RECOMMENDED OPERATING CONDITIONS

(T=25°C, VDD=3.0V 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)

avg

= 3.0 V

0.1

µA

Current consumption into

MCLK (3)

MCLK=32768Hz 0.5 µA

Operating temperature

Range

-40 +25 +85 °C

Conversion time (15 Bit) T

conv

MCLK=32768Hz 35 ms

External clock signal (4) MCLK 30000 32768 35000 Hz

Duty cycle of MCLK 40/60 50/50 60/40 %

Serial data clock 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 MS5541C.

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 2ms.

3) This value can be reduced by switching off MCLK while MS5541C 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 .. 85°C, VDD = 2.2 V .. 3.6 V)

Parameter Symbol Conditions Min Typ Max Unit

Input High Voltage V

80% VDD 100% VDD V

Input Low Voltage V

0% VDD 20% VDD V

Signal Rise Time t

200 ns

Signal Fall Time t

200 ns

DIGITAL OUTPUTS

(T=-40°C .. 85°C, V

= 2.2V..3.6V)

Parameter Symbol Conditions Min Typ Max Unit

Output High Voltage V

Source

= 0.6 mA 80% VDD 100% VDD V

Output Low Voltage V

Sink

= 0.6 mA 0% VDD 20% VDD V

Signal Rise Time t

200 ns

Signal Fall Time t

200 ns

AD-CONVERTER

(T=25°C, V

=3.0V)

Parameter Symbol Conditions Min Typ Max Unit

Resolution 15 Bit

Linear Range 4000 40000 LSB

Conversion Time MCLK=32768Hz 35 ms

INL within linear

Range -5 5 LSB

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PRESSURE OUTPUT CHARACTERISTICS

With the calibration data stored in the interface IC of the MS5541C the following characteristics can be achieved:

(VDD = 3.0 V unless noted otherwise)

Parameter Conditions Min Typ Max Unit Note

Resolution 1.2 mbar 1

Absolute Pressure Accuracy

(Temperature range 0 .. +40 °C)

p = 0 .. 5bar

p = 0 .. 10bar

p = 0 .. 14bar

-20

-40

-100

+20

mbar

Absolute Pressure Accuracy

(Temperature range -40 .. +85 °C)

p = 0 .. 5bar

p = 0 .. 10bar

p = 0 .. 14bar

-40

-60

-160

+100

+180

+200

mbar

Error over Temperature

(p = const. relative to 20°C) T

= -40…+85°C -10 +100 mbar

Long-term Stability 6 months 20 mbar 4

Maximum Error over Supply

Voltage VDD = 2.2…3.6V -16 16 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) With the second-order temperature compensation as described in Section “FUNCTION". See next section

for typical operating curves.

4) 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. The reference temperature is 20°C.

Parameter Conditions Min Typ Max Unit Note

Resolution 0.005 0.015 °C

= 20°C -0.8 0.8 °C

Accuracy T

= -40…+85°C -2 +6 °C 1

Maximum Error over Supply

Voltage VDD = 2.2…3.6V -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

0 2000 4000 6000 8000 10000 12000 14000

Pressure (mbar)

ADC-value D1 (LSB)

-40°C

25°C

85°C

ADC-value D2 vs Temperature (typical)

15000

20000

25000

30000

35000

40000

-40 -20 0 20 40 60 80

Temperature (°C)

ADC-value D2 (LSB)

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Absolute Pressure Accuracy after Calibration, 1st order compensation

-100

-50

100

150

200

250

0 2000 4000 6000 8000 10000 12000 14000

Pressure (mbar)

Pressure error (mbar)

85°C

60°C

25°C

0°C

-40°C

Absolute Pressure Accuracy after Calibration, 2nd order compensation

-100

-80

-60

-40

-20

0 2000 4000 6000 8000 10000 12000 14000

Pressure (mbar)

Pressure error (mbar)

85°C

60°C

25°C

0°C

-40°C

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Temperature Error Accuracy vs temperature (typical)

-5

-40 -20 0 20 40 60 80

Temperature (°C)

Temperature error (°C)

Temperature error (standard

calculation)

Temperature error (with 2nd

order calculation)

Pressure Error Accuracy vs temperature (typical)

-50

-25

100

-40 -20 0 20 40 60 80

Temperature (°C)

Pressure error (mbar)

Pres. error 4bar (1st order)

Pres. error 4bar (2nd order)

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Pressure error vs supply voltage (typical)

-10

-8

-6

-4

-2

2.2 2.4 2.6 2.8 3 3.2 3.4 3.6

Voltage (V)

Pressure error (mbar)

14000 mbar

6000 mbar

1000 mbar

Temperature error vs supply voltage (typical)

-0.15

-0.1

-0.05

0.05

0.1

0.15

2.2 2.4 2.6 2.8 3 3.2 3.4 3.6

Voltage (V)

Temperature error (°C)

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FUNCTION

GENERAL

The MS5541C consists of a piezoresistive sensor and a sensor interface IC. The main function of the MS5541C

is to convert the uncompensated analog output voltage from the piezoresistive pressure sensor into a 16-Bit

digital value, as well as providing 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

necessary to compensate for these effects. This compensation procedure must be performed by software using

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 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 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 flow chart, 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 MS5541C. 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 word 1 to word 4).

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”.

Senso

Word1..4

Calculation

in external

micro-

controller

Pressure

Temperature

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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 MS5541

Read digital pressure value from MS5541

D1 (16 Bit)

Read digital temperature value from MS5541

Display pressure and temperature value

Basic equations:

Calculate calibration temperature

UT1=8*C5+10000

Calculate temperature compensated pressure

Difference between actual temperature and reference

temperature:

dT = D2 - UT1

Actual temperature:

TEMP = 200 + dT*(C6+100)/2

(0.1°C)

Calculate actual temperature

D2 (16 Bit)

SENST1

OFFT1

TCS

TCO

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)

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

+ 10000

Sensitivity at actual temperature:

SENS = C1/2 + ((C3+200)*dT)/2

+ 3000

Temperature compensated pressure in mbar:

P = (SENS * (D1-OFF))/2

+ 1000

OFF(D2)=OFFT1+TCO*dT(D2)

SENS(D2)=SENST1+TCS*dT(D2)

P(D1,D2)=D1*SENS(D2)-OFF(D2)

dT = 587

TEMP = 243

= 24.3 °C

OFF = 14859

SENS = 4198

P = 4001

= 4001 mbar

UT1 = 26016

Fig. 3: Flow chart for pressure/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 4 to 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 calibration data in Word1 to Word4.

SECOND-ORDER TEMPERATURE COMPENSATION

In order to obtain full temperature 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:

High Temperatures

dT2 = dT – (dT/128*dT/128)/8

dT < 0

yes

Calculate temperature

TEMP = (200 + dT2*(C6+100)/211) (0.1°C)

Low Temperatures

dT2 = dT – (dT/128*dT/128)/2

≥

yes

Fig. 5: Flow chart for calculating the temperature and pressure to the optimum accuracy.

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SERIAL INTERFACE

The MS5541C 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 transfer with each Bit being sampled by the MS5541C on the rising edge of SCLK and each Bit being sent

by the MS5541C 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 MS5541C with the falling edge of SCLK. The SCLK-signal is generated by

the microprocessor’s system. The digital data provided by the MS5541C 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 “D1” (Figure 6a)

• Conversion start for temperature measurement and ADC-data-out “D2” (Figure 6b)

• Calibration data read-out sequence for word 1 (Figure 6c)

• Calibration data read-out sequence for word 2 (Figure 6d)

• Calibration data read-out sequence for word 3 (Figure 6c)

• Calibration data read-out sequence for word 4 (Figure 6d)

• RESET sequence (Figure 6e)

Every communication starts with an instruction sequence at pin DIN. Fig. 6 shows the timing diagrams for the

MS5541C. 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

16-Bit word by giving another 17 clocks on the SLCK pin. It is possible to interrupt the data read-out sequence

with a hold of the SCLK signal.

It is important to always read out the last conversion result before starting a new conversion.

The RESET-sequence is special as its unique pattern is recognized by the module in any state. By consequence

it can be used to restart if synchronization between the microcontroller and the MS5541C 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.

sequence: START+P-measurement

SCLKDOUTDIN

Bit7

Conversion start for pressure measurement and ADC-data-out "D1":

end of conversion

Bit6Bit5Bit4Bit3Bit2Bit1Bit0

conversion

(33ms)

DB7

ADC-data out

MSB

ADC-data out

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

SCLKDOUTDIN

Bit7

Conversion start for temperature measurement and ADC-data-out "D2":

end of conversion

Bit6Bit5Bit4Bit3Bit2Bit1Bit0

conversion

(33ms)

Bit8 Bit9

Start-bit Stop-bitSetup-bits

start of conversion

DB7

ADC-data out

MSB

ADC-data out

LSB

DB6 DB5 DB4 DB3 DB2 DB1 DB0 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0

Fig. 6b: D2 acquisition sequence

sequence: coefficient read + address

SCLKDOUTDIN

Bit7

Calibration data read out sequence for word 1/ word 3:

Bit6Bit5Bit4Bit3Bit2Bit1Bit0

DB7

coefficient-data out

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: W1, W3 reading sequence

address word 2

address word 4

sequence: coefficient read + address

SCLKDOUTDIN

Bit7

Calibration data read out sequence for word 2/ word 4:

Bit6Bit5Bit4Bit3Bit2Bit1Bit0

DB7

coefficient-data out

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 reading sequence

sequence: RESET

SCLKDOUTDIN

Bit7

RESET - sequence:

Bit6Bit5Bit4Bit3Bit2Bit1Bit0 Bit8 Bit9 Bit10 Bit11Bit12 Bit13 Bit14 Bit15

Fig. 6e: Reset sequence (21-Bit)

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APPLICATION INFORMATION

GENERAL

The advantage for this combination of a 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 MS5541C 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 MS5541C 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 silicon pressure transducer and the bonding wires are protected by an anticorrosive and antimagnetic

protection cap. The MS5541C 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 and antimagnetic stainless steel in order to avoid

any corrosive battery effects inside the final product. The MS5541C was qualified referring to the ISO 6425

standard and can withstand a pressure of 30 bar in salt water. The concentration of the see water used for the

qualification is 41 g of see salt for 1 litre of DI water.

For underwater operations like specified in ISO 6425 standard it is important to seal the sensor with a rubber O-

Ring around the metal Ring. Any salt water coming to the contact side (ceramic and Pads) of the sensor could

lead to permanent damage. For "water-resistant" 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 MS5541C is protected against sunlight by a layer of white gel. It is, however, important to note that the

sensor may still be slightly 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 MS5541C'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 47µF tantalum capacitor must be

placed as close as possible of the MS5541C's VDD pin. This capacitor will stabilize the power supply during data

conversion and thus, provide the highest possible accuracy.

APPLICATION EXAMPLE: DIVING COMPUTER SYSTEM USING MS5541C

MS5541C 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 3V, particularly in battery applications. The MS5541C

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.

4/8bit-Microcontroller

LCD-Display

EEPROM

Keypad

MS5541

SCLK

DIN

DOUT

MCLK

XTAL1

XTAL2

32.768 kHz

optional

VDD

GND

VDD

GND

3V-Battery

47uF

Tantal

Fig. 7: Demonstration of MS5541C in a diving computer

RECOMMENDED PAD LAYOUT

Pad layout for bottom side of MS5541C soldered onto printed circuit board

Fig. 8: Pad layout of MS5541C

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DEVICE PACKAGE OUTLINES

Fig. 9: Device package outlines of MS5541C

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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 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).

MOUNTING

The MS5541C 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.

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!

SEALING WITH O-RING

In products like diving computers the electronics must be protected against direct water or humidity. For those

products the MS5541C provides the possibility to seal with an O-ring. The protective cap of the MS5541C is

made of special anticorrosive stainless steel with a polished surface. In addition to this the MS5541C 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.

CLEANING

The MS5541C 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 according 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

MS5541C 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.

DA5541C_001.doc February 19th, 2008 19

000055411194 ECN1037

ORDERING INFORMATION

Product

Code Product Art.-Nr. Package Comments

MS5541-CM

Miniature 14 bar

module with

metal cap

325541009

SMD hybrid with solder paste,

anticorrosive and antimagnetic

metal protection cap, silicon gel

sensor protection

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.