Data sheet
BMP085
Digital pressure sensor
Bosch Sensortec
BMP085: Data sheet
Document revision
1.3
Document release date
22 August 2011
Document number
BST-BMP085-DS000-06
Technical reference code(s)
0 273 300 144
Notes
Data in this document are subject to change without notice. Product
photos and pictures are for illustration purposes only and may differ from
the real product’s appearance.
Data sheet
BMP085
Page 2
BMP085
DIGITAL PRESSURE SENSOR
Key features
• Pressure range:
• Supply voltage:
300 ... 1100hPa (+9000m ... -500m above sea level)
1.8 ... 3.6V (VDDA)
1.62V ... 3.6V (VDDD)
•
LCC8 package:
Robust, ceramic lead-less chip carrier (LCC) package
Small footprint:
5.0mm x 5.0mm
Super-flat:
1.2mm height
•
Low power:
5μA at 1 sample / sec. in standard mode
•
Low noise:
0.06hPa (0.5m) in ultra low power mode
0.03hPa (0.25m) ultra high resolution mode
down to 0.1m (rms noise) possible
•
•
•
•
•
Temperature measurement included
I2C interface
Fully calibrated
Pb-free, halogen-free and RoHS compliant,
MSL 1
General Description
The BMP085 is the fully pin- and function compatible successor of the SMD500, a new
generation of high precision digital pressure sensors for consumer applications. The universal
C-code SMD500/BMP085 (“BMP085_SMD500_API”) is fully upward compatible to SMD500 and
recognizes automatically the device ID. Customers already working with the SMD500 pressure
sensor are invited to contact Bosch Sensortec as soon as they intend to switch-over to the
BMP085 sensor for getting first-hand support.
The ultra-low power, low voltage electronics of the BMP085 is optimized for use in mobile
phones, PDAs, GPS navigation devices and outdoor equipment. With a low altitude noise of
merely 0.25m at fast conversion time, the BMP085 offers superior performance. The I2C
interface allows for easy system integration with a microcontroller.
The BMP085 is based on piezo-resistive technology for EMC robustness, high accuracy and
linearity as well as long term stability.
Robert Bosch is the world market leader for pressure sensors in automotive applications. Based
on the experience of over 200 million pressure sensors in the field, the BMP085 continues a
new generation of micro-machined pressure sensors.
BST-BMP085-DS000-06 | Revision 1.3 | August 2011
Bosch Sensortec
© Bosch Sensortec GmbH reserves all rights even in the event of industrial property rights. We reserve all rights of disposal such as copying and passing on to
third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.
Note: Specifications within this document are subject to change without notice.
Data sheet
BMP085
Page 3
Typical applications
• Enhancement of GPS navigation (dead-reckoning, slope detection, etc.)
• In- and out-door navigation
• Leisure and sports
• Weather forecast
• Vertical velocity indication (rise/sink speed)
New features comparison
Smaller package height
Faster conversion time (standard mode each)
Faster I2C data transfer
Extended min. supply voltage
Lower stand-by current (typ.)
External clock
BST-BMP085-DS000-06 | Revision 1.3 | August 2011
BMP085
1.2mm
7.5ms (max.)
max. 3.4MHz
min. 1.8V
0.1μA
not necessary
SMD500
1.55mm
34ms
max. 400kHz
min. 2.2V
0.7μA
necessary
Bosch Sensortec
© Bosch Sensortec GmbH reserves all rights even in the event of industrial property rights. We reserve all rights of disposal such as copying and passing on to
third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.
Note: Specifications within this document are subject to change without notice.
Data sheet
BMP085
Page 4
Index of Contents
1. ELECTRICAL CHARACTERISTICS ....................................................................................... 6
2. ABSOLUTE MAXIMUM RATINGS .......................................................................................... 8
3. OPERATION ............................................................................................................................ 9
3.1 GENERAL DESCRIPTION......................................................................................................... 9
3.2 GENERAL FUNCTION AND APPLICATION SCHEMATICS .............................................................. 9
3.3 MEASUREMENT OF PRESSURE AND TEMPERATURE ............................................................... 11
3.4 CALIBRATION COEFFICIENTS ............................................................................................... 12
3.5 CALCULATION PRESSURE AND TEMPERATURE ...................................................................... 13
3.6 CALCULATION ABSOLUTE ALTITUDE ..................................................................................... 15
3.7 CALCULATING PRESSURE AT SEA LEVEL ............................................................................... 15
4. I²C INTERFACE ..................................................................................................................... 16
4.1 I²C SPECIFICATION .............................................................................................................. 16
4.2 DEVICE AND REGISTER ADDRESS ......................................................................................... 17
4.3 I²C PROTOCOL .................................................................................................................... 17
4.4 START TEMPERATURE AND PRESSURE MEASUREMENT ......................................................... 18
4.5 READ A/D CONVERSION RESULT OR E²PROM DATA ............................................................ 19
5. PACKAGE ............................................................................................................................. 20
5.1 PIN CONFIGURATION ........................................................................................................... 20
5.2 OUTLINE DIMENSIONS ......................................................................................................... 21
5.2.1 TOP VIEW.................................................................................................................................. 21
5.2.2 TOP VIEW WITH LID .................................................................................................................... 22
5.2.3 SIDE VIEW WITH LID.................................................................................................................... 22
5.3 DEVICE MARKING ................................................................................................................ 22
5.4 TAPE ON REEL .................................................................................................................... 23
5.5 PRINTED CIRCUIT BOARD (PCB) DESIGN .............................................................................. 24
5.6 MOISTURE SENSITIVITY LEVEL AND SOLDERING .................................................................... 24
5.7 ROHS COMPLIANCY ............................................................................................................ 25
5.8 MOUNTING AND ASSEMBLY RECOMMENDATIONS .................................................................. 25
BST-BMP085-DS000-06 | Revision 1.3 | August 2011
Bosch Sensortec
© Bosch Sensortec GmbH reserves all rights even in the event of industrial property rights. We reserve all rights of disposal such as copying and passing on to
third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.
Note: Specifications within this document are subject to change without notice.
Data sheet
BMP085
Page 5
6. LEGAL DISCLAIMER ............................................................................................................ 26
6.1 ENGINEERING SAMPLES ...................................................................................................... 26
6.2 PRODUCT USE .................................................................................................................... 26
6.3 APPLICATION EXAMPLES AND HINTS ..................................................................................... 26
7. DOCUMENT HISTORY AND MODIFICATIONS ................................................................... 27
BST-BMP085-DS000-06 | Revision 1.3 | August 2011
Bosch Sensortec
© Bosch Sensortec GmbH reserves all rights even in the event of industrial property rights. We reserve all rights of disposal such as copying and passing on to
third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.
Note: Specifications within this document are subject to change without notice.
Data sheet
BMP085
Page 6
1. Electrical characteristics
If not stated otherwise, the given values are maximum values over temperature/voltage range in
the given operation mode.
Table 1: Electrical characteristics
Parameter
Symbol
Operating
temperature
TA
Supply voltage
VDD
Condition
Min
operational
-40
+85
full accuracy
0
+65
ripple max. 50mVpp
1.8
2.5
3.6
V
1.62
2.5
3.6
V
VDDIO
Typ
Max
Units
°C
IDDLOW
ultra low power mode
3
μA
IDDSTD
standard mode
5
μA
IDDHR
high resolution mode
7
μA
IDDUHR
ultra high res. mode
12
μA
Peak current
Ipeak
during conversion
650
Standby current
IDDSBM
at 25°C
0.1
Serial data clock
fSCL
Conversion time
temperature
tC_temp
standard mode
tc_p_low
Supply current
@ 1 sample / sec.
25°C
Conversion time
pressure
1000
μA
μA
3.4
MHz
3
4.5
ms
ultra low power mode
3
4.5
ms
tc_p_std
standard mode
5
7.5
ms
tc_p_hr
high resolution mode
9
13.5
ms
tc_p_luhr
ultra high res. mode
17
25.5
ms
Absolute accuracy
pressure
VDD = 3.3V
Resolution of
output data
Relative accuracy
pressure
VDD = 3.3V
BST-BMP085-DS000-06 | Revision 1.3 | August 2011
700 . . . 1100 hPa
0 . . . +65 °C
-2.5
±1.0
+2.5
hPa
300 . . . 700 hPa
0 . . . +65 °C
-3.0
±1.0
+3.0
hPa
300 . . . 1100 hPa
-20 . . . 0 °C
-4.0
±1.5
+4.0
hPa
pressure
0.01
hPa
temperature
0.1
°C
700 . . . 1100 hPa
@ 25 °C
±0.2
hPa
0 . . . 65 °C @ p
const.
±0.5
hPa
Bosch Sensortec
© Bosch Sensortec GmbH reserves all rights even in the event of industrial property rights. We reserve all rights of disposal such as copying and passing on to
third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.
Note: Specifications within this document are subject to change without notice.
Data sheet
BMP085
Noise in pressure
Absolute accuracy
temperature
VDD = 3.3V
Page 7
see table on page 12
@ 25 °C
-1.5
±0.5
+1.5
°C
0 . . . +65 °C
-2.0
±1.0
+2.0
°C
Solder drifts
Minimum solder
height 50μm
±1.0
hPa
Long term stability
12 months
±1.0
hPa
BST-BMP085-DS000-06 | Revision 1.3 | August 2011
Bosch Sensortec
© Bosch Sensortec GmbH reserves all rights even in the event of industrial property rights. We reserve all rights of disposal such as copying and passing on to
third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.
Note: Specifications within this document are subject to change without notice.
Data sheet
BMP085
Page 8
2. Absolute maximum ratings
Table 2: Absolute maximum ratings
Parameter
Condition
Storage temperature
Supply voltage
all pins
ESD rating
HBM, R = 1.5kΩ,
C = 100pF
Overpressure
Min
Max
Units
-40
+85
°C
-0.3
+4.25
V
±2
kV
10,000
hPa
The BMP085 has to be handled as Electrostatic Sensitive Device (ESD).
Figure 1: ESD
BST-BMP085-DS000-06 | Revision 1.3 | August 2011
Bosch Sensortec
© Bosch Sensortec GmbH reserves all rights even in the event of industrial property rights. We reserve all rights of disposal such as copying and passing on to
third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.
Note: Specifications within this document are subject to change without notice.
Data sheet
BMP085
Page 9
3. Operation
3.1 General description
The BMP085 is designed to be connected directly to a microcontroller of a mobile device via the
I2C bus. The pressure and temperature data has to be compensated by the calibration data of
the E2PROM of the BMP085.
3.2 General function and application schematics
The BMP085 consists of a piezo-resistive sensor, an analog to digital converter and a control
unit with E2PROM and a serial I2C interface. The BMP085 delivers the uncompensated value of
pressure and temperature. The E2PROM has stored 176 bit of individual calibration data. This is
used to compensate offset, temperature dependence and other parameters of the sensor.
• UP = pressure data (16 to 19 bit)
• UT = temperature data (16 bit)
BST-BMP085-DS000-06 | Revision 1.3 | August 2011
Bosch Sensortec
© Bosch Sensortec GmbH reserves all rights even in the event of industrial property rights. We reserve all rights of disposal such as copying and passing on to
third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.
Note: Specifications within this document are subject to change without notice.
Data sheet
BMP085
Page 10
Typical application circuit:
1.8 ... 3.6V
100nF
Rp(1)
VDDA
Rp(1)
VDDD
2
E PROM
μController
e. g. 8 bit
BMP085
EOC
Control
Unit
SDA
SCL
I2C interface
XCLR
Sensor
element
ADC
GND
Note:
(1) Pull-up resistors for I2C bus, Rp = 2.2kΩ ... 10kΩ, typ. 4.7kΩ
Display
Note:
The BMP085 can be supplied independently with different levels of VDDA and VDDD, which is not
possible with the SMD500. In case of different voltage levels, VDDA and VDDD shall have a 100nF
decoupling capacitor each.
BST-BMP085-DS000-06 | Revision 1.3 | August 2011
Bosch Sensortec
© Bosch Sensortec GmbH reserves all rights even in the event of industrial property rights. We reserve all rights of disposal such as copying and passing on to
third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.
Note: Specifications within this document are subject to change without notice.
Data sheet
BMP085
Page 11
3.3 Measurement of pressure and temperature
For all calculations presented here an ANSI C code is available from Bosch Sensortec
(“BMP085_SMD500_API”).
The microcontroller sends a start sequence to start a pressure or temperature measurement.
After converting time, the result value (UP or UT, respectively) can be read via the I2C interface.
For calculating temperature in °C and pressure in hPa, the calibration data has to be used.
These constants can be read out from the BMP085 E2PROM via the I2C interface at software
initialization.
The sampling rate can be increased up to 128 samples per second (standard mode) for
dynamic measurement. In this case, it is sufficient to measure the temperature only once per
second and to use this value for all pressure measurements during the same period.
By using different modes the optimum compromise between power consumption, speed and
resolution can be selected, see below table.
Start
Start temperature
measurement
wait 4.5ms
Read UT
Start pressure
measurement
wait (depends on mode, see below)
Read UP
Calculate pressure and
temperature in physical
units
Figure 2: Measurement of pressure and temperature
BST-BMP085-DS000-06 | Revision 1.3 | August 2011
Bosch Sensortec
© Bosch Sensortec GmbH reserves all rights even in the event of industrial property rights. We reserve all rights of disposal such as copying and passing on to
third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.
Note: Specifications within this document are subject to change without notice.
Data sheet
BMP085
Page 12
Table 3: Overview of BMP085 modes, selected by driver software via the variable
oversampling_setting
Mode
Parameter
oversampling_
setting
Internal
number
of
samples
Conversion
time
pressure
max. [ms]
Avg.
current @
1 sample/s
typ. [μA]
RMS
noise
typ. [hPa]
RMS
noise
typ. [m]
ultra low power
0
1
4.5
3
0.06
0.5
standard
1
2
7.5
5
0.05
0.4
high resolution
2
4
13.5
7
0.04
0.3
ultra high
resolution
3
8
25.5
12
0.03
0.25
The noise data is calculated as standard deviation of 10 data points. For further information on
noise characteristics see the relevant application note “Noise in pressure sensor applications”.
All modes can be performed at higher speeds, e.g. up to 128 times per second for standard
mode, with the current consumption increasing proportionally to the sample rate. This way the
noise can be decreased further by software averaging.
3.4 Calibration coefficients
The 176 bit E2PROM is partitioned in 11 words of 16 bit each. These contain 11 calibration
coefficients. Every sensor module has individual coefficients. Before the first calculation of
temperature and pressure, the master reads out the E2PROM data.
The data communication can be checked by checking that none of the words has the value 0 or
0xFFFF.
Table 4: Calibration coefficients
BMP085 reg adr
BST-BMP085-DS000-06 | Revision 1.3 | August 2011
Parameter
MSB
LSB
AC1
0xAA
0xAB
AC2
0xAC
0xAD
AC3
0xAE
0xAF
AC4
0xB0
0xB1
AC5
0xB2
0xB3
AC6
0xB4
0xB5
B1
0xB6
0xB7
B2
0xB8
0xB9
MB
0xBA
0xBB
MC
0xBC
0xBD
MD
0xBE
0xBF
Bosch Sensortec
© Bosch Sensortec GmbH reserves all rights even in the event of industrial property rights. We reserve all rights of disposal such as copying and passing on to
third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.
Note: Specifications within this document are subject to change without notice.
Data sheet
BMP085
Page 13
3.5 Calculation pressure and temperature
The mode (ultra low power, standard, high, ultra high resolution) can be selected by the variable
oversampling_setting (0, 1, 2, 3) in the C code.
The universal code SMD500/BMP085 is fully upward compatible to SMD500 and recognizes
automatically the device ID. Thus, the SMD500 can be replaced "on the fly" by the BMP085
without changing hardware or software.
Calculation of true temperature and pressure in steps of 1Pa (= 0.01hPa = 0.01mbar) and
temperature in steps of 0.1°C.
The following figure shows the detailed algorithm for pressure and temperature measurement.
This algorithm is available to customers as reference C source code (“BMP085_SMD500_API”)
from Bosch Sensortec and via its sales and distribution partners. Please contact your Bosch
Sensortec representative for details.
BST-BMP085-DS000-06 | Revision 1.3 | August 2011
Bosch Sensortec
© Bosch Sensortec GmbH reserves all rights even in the event of industrial property rights. We reserve all rights of disposal such as copying and passing on to
third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.
Note: Specifications within this document are subject to change without notice.
Data sheet
BMP085
Page 14
Calculation of pressure and temperature for BMP085
Start
C code function:
example:
Read calibration data
2
from the E PROM of the BMP085
2
read out E PROM registers, 16 bit, MSB first
AC1 (0xAA, 0xAB)
(16 bit)
AC2 (0xAC, 0xAD)
(16 bit)
AC3 (0xAE, 0xAF)
(16 bit)
AC4 (0xB0, 0xB1)
(16 bit)
AC5 (0xB2, 0xB3)
(16 bit)
AC6 (0xB4, 0xB5)
(16 bit)
B1 (0xB6, 0xB7)
(16 bit)
B2 (0xB8, 0xB9)
(16 bit)
MB (0xBa, 0xBB)
(16 bit)
MC (0xBC, 0xBD)
(16 bit)
MD (0xBE , 0xBF)
(16 bit)
read uncompensated temperature value
write 0x2E into reg 0xF4, wait 4.5ms
read reg 0xF6 (MSB), 0xF7 (LSB)
UT = MSB << 8 + LSB
read uncompensated pressure value
write 0x34+(oss<<6) into reg 0xF4, wait
read reg 0xF6 (MSB), 0xF7 (LSB), 0xF8 (XLSB)
UP = (MSB<<16 + LSB<<8 + X LSB) >> (8-oss)
calculate true temperature
15
X1 = (UT - AC6) * AC5 / 2
11
X2 = MC * 2 / (X1 + MD)
B5 = X1 + X2
4
T = (B5 + 8) / 2
calculate true pressure
B6 = B5 - 4000
12
11
X1 = (B2 * (B6 * B6 / 2 )) / 2
11
X2 = AC2 * B6 / 2
X3 = X1 + X2
B3 = ((AC1*4+X3) << oss + 2) / 4
13
X1 = AC3 * B6 / 2
12
16
X2 = (B1 * (B6 * B6 / 2 )) / 2
2
X3 = ((X1 + X2) + 2) / 2
15
B4 = AC4 * (unsigend long)(X3 + 32768) / 2
B7 = ((unsigned long)UP - B3) * (50000 >> oss)
if (B7 < 0x80000000) { p = (B7 * 2) / B4 }
else { p = (B7 / B4) * 2 }
8
8
X1 = (p / 2 ) * (p / 2 )
16
X1 = (X1 * 3038) / 2
16
X2 = (-7357 * p) / 2
4
p = p + (X 1 + X2 + 3791) / 2
type:
bmp085_get_ cal_ param
AC1 =
AC2 =
AC3 =
AC4 =
AC5 =
AC6 =
B1 =
B2 =
MB =
MC =
MD =
408
-72
-14383
32741
32757
23153
6190
4
-32768
-8711
2868
short
short
short
unsigned short
unsigned short
unsigned short
short
short
short
short
short
bmp085_get_ut
UT =
long
27898
oss =
0
= oversampling_setting
(ultra low powe r mode)
UP =
23843
X1 =
X2 =
B5 =
T=
4743
-2344
2399
150
B6 =
X1 =
X2 =
X3 =
B3 =
X1 =
X2 =
X3 =
B4 =
B7 =
p=
-1601
1
56
57
422
2810
59
717
33457
1171050000
70003
X1 =
X1 =
X2 =
p=
74529
3454
-7859
69964
short (0 .. 3)
bmp085_get_up
long
bmp085_ get_temperature
temp in 0.1°C
long
long
long
long
BMP085 calpressure
press. in Pa
long
long
long
long
long
long
long
long
unsigned long
unsigned long
long
long
long
long
long
long
display temperature and pressure value
Figure 3: Calculating pressure and temperature for BMP085
BST-BMP085-DS000-06 | Revision 1.3 | August 2011
Bosch Sensortec
© Bosch Sensortec GmbH reserves all rights even in the event of industrial property rights. We reserve all rights of disposal such as copying and passing on to
third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.
Note: Specifications within this document are subject to change without notice.
Data sheet
BMP085
Page 15
3.6 Calculation absolute altitude
With the measured pressure p and the pressure at sea level p0 e.g. 1013.25hPa, the altitude in
meters can be calculated with the international barometric formula:
p
altitude = 44330 * 1 -
p0
1
5.255
9000
8000
7000
6000
5000
4000
3000
2000
1000
0
-1000
11
00
10
00
90
0
80
0
70
0
60
0
50
0
Altitude in standard
atmosphere
40
0
30
0
Altitude above sea level [m]
Thus, a pressure change of ∆p = 1hPa corresponds to 8.43m at sea level
Barometric pressure [hPa]
Figure 4: Calculation absolute altitude
3.7 Calculating pressure at sea level
With the measured pressure p and the absolute altitude the pressure at sea level can be
calculated:
p0 =
p
altitude
1
44330
5.255
Thus, a difference in altitude of ∆altitude = 10m corresponds to 1.2hPa pressure change at sea
level.
BST-BMP085-DS000-06 | Revision 1.3 | August 2011
Bosch Sensortec
© Bosch Sensortec GmbH reserves all rights even in the event of industrial property rights. We reserve all rights of disposal such as copying and passing on to
third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.
Note: Specifications within this document are subject to change without notice.
Data sheet
BMP085
Page 16
4. I²C Interface
•
•
•
I²C is a digital two wire interface
Clock frequencies up to 3.4mBit/sec (I²C standard, fast and high-speed mode supported)
SCL and SDA needs a pull-up resistor, typ. 4.7 kOhm to VDDD (one resistor each for all
the I²C bus)
The I2C bus is used to control the sensor, to read calibration data from the E2PROM and to
read the measurement data when A/D conversion is finished. SDA (serial data) and SCL
(serial clock) have open-drain outputs.
For detailed I2C-bus specification please refer to:
http://www.nxp.com/acrobat_download/literature/9398/39340011.pdf
The BMP085 has a master clear (XCLR) low-active input that is used to reset the BMP085 and
initializes internal registers and counters. The device is automatically reset by power on reset
(POR) circuitry. XCLR can be left floating if not used. The pad has an internal pull-up resistor of
typ. 120kOhm.
4.1 I²C specification
Table 5: Electrical parameters for the I2C interface
Parameter
Symbol
Clock input frequency
fSCL
Input-low level
VIL
Input-high level
Max.
Units
3.4
MHz
0
0.2 * VDDD
V
VIH
0.8 * VDDD
VDDD
V
SDA and SCL pull-up resistor
Rpull-up
2.2
10
kOhm
SDA sink current
@ VDDD = 1.62V, VOL = 0.3V
ISDA_sink
9
mA
EOC sink current
@ VDDD = 1.62V, VOL = 0.3V
ISDA_sink
7.7
mA
EOC source current
@ VDDD = 1.62V, VOH = 1.32V
ISDA_source
1.5
mA
XCLR pulse length
tXCLR
1
μs
Start-up time after power-up, before
first communication
tStart
10
ms
BST-BMP085-DS000-06 | Revision 1.3 | August 2011
Min.
Typ
Bosch Sensortec
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third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.
Note: Specifications within this document are subject to change without notice.
Data sheet
BMP085
Page 17
4.2 Device and register address
The BMP085 module address is shown below. The LSB of the device address distinguishes
between read (1) and write (0) operation, corresponding to address 0xEF (read) and 0xEE
(write).
A7
1
A6
1
A5
1
A4
0
A3
1
A2
1
A1
1
W/R
0/1
There is an easy way to connect two BMP085 to the same I2C bus: You can use the XCLR input
of BMP085 to set one BMP085 part silent while you communicate with the other BMP085 part
via I2C and vice versa. The signals can be provided by two digital outputs of the microcontroller,
or one digital output and one inverter.
4.3 I²C protocol
The I2C interface protocol has special bus signal conditions. Start (S), stop (P) and binary data
conditions are shown below. At start condition, SCL is high and SDA has a falling edge. Then
the slave address is sent. After the 7 address bits, the direction control bit R/W selects the read
or write operation. When a slave device recognizes that it is being addressed, it should
acknowledge by pulling SDA low in the ninth SCL (ACK) cycle.
At stop condition, SCL is also high, but SDA has a rising edge. Data must be held stable at SDA
when SCL is high. Data can change value at SDA only when SCL is low.
Figure 5: I²C protocol
BST-BMP085-DS000-06 | Revision 1.3 | August 2011
Bosch Sensortec
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third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.
Note: Specifications within this document are subject to change without notice.
Data sheet
BMP085
Page 18
4.4 Start temperature and pressure measurement
The timing diagrams to start the measurement of the temperature value UT and pressure value
UP are shown below. After start condition the master sends the device address write, the
register address and the control register data. The BMP085 sends an acknowledgement
(ACKS) every 8 data bits when data is received. The master sends a stop condition after the
last ACKS.
SCL
SDA
Module address
write 0xEE
S
Register address
0xF4
Control register
data 0xF4
ACKS
ACKS
ACKS
P
Figure 6: Timing diagram for starting pressure measurement
Abbreviations:
S
P
ACKS
ACKM
NACKM
Start
Stop
Acknowledge by Slave
Acknowledge by Master
Not Acknowledge by Master
Table 6: Control registers values for different internal oversampling_setting (osrs)
Measurement
Control register
value
(register address
0xF4)
Max. conversion
time
[ms]
Temperature
0x2E
4.5
Pressure
(osrs = 0)
0x34
4.5
Pressure
(osrs = 1)
0x74
7.5
Pressure
(osrs = 2)
0xB4
13.5
Pressure
(osrs = 3)
0xF4
25.5
Instead of waiting for the maximum conversion time, the output pin EOC (end of conversion)
can be used to check if the conversion is finished (logic 1) or still running (logic 0). After the
conversion is finished BMP085 switches automatically in standby mode.
BST-BMP085-DS000-06 | Revision 1.3 | August 2011
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third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.
Note: Specifications within this document are subject to change without notice.
Data sheet
BMP085
Page 19
4.5 Read A/D conversion result or E²PROM data
To read out the temperature data word UT (16 bit), the pressure data word UP (16 to 19 bit) and
the E2PROM data proceed as follows:
After the start condition the master sends the module address write command and register
address. The register address selects the read register:
E2PROM data registers
Temperature or pressure value UT or UP
0xAA to 0xBF
0xF6 (MSB), 0xF7 (LSB), optionally 0xF8 (XLSB)
Then the master sends a restart condition followed by the module address read that will be
acknowledged by the BMP085 (ACKS). The BMP085 sends first the 8 MSB, acknowledged by
the master (ACKM), then the 8 LSB. The master sends a "not acknowledge" (NACKM) and
finally a stop condition.
Optionally for ultra high resolution, the XLSB register with address 0xF8 can be read to extend
the 16 bit word to up to 19 bits; refer to the application programming interface (API) software
rev. 1.1 (“BMP085_SMD500_API”, available from Bosch Sensortec).
SCL
SDA
Module address
write 0xEE
S
MSB e.g.
Register address
LSB e.g.
Module address
ADC result 0x5C
e.g. 0xF6
ADC result 0x96
read 0xEF
NACKM P
ACKS Restart
ACKS
ACKS
ACKM
Figure 7: Timing diagram read 16 bit A/D conversion result
BST-BMP085-DS000-06 | Revision 1.3 | August 2011
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third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.
Note: Specifications within this document are subject to change without notice.
Data sheet
BMP085
Page 20
5. Package
5.1 Pin configuration
Picture shows the device in top view. Device pins are shown here transparently only for
orientation purposes.
Figure 8: Pin configuration
Table 7: Pin configuration
Pin No.
Name
Function
Type
1
GND
Ground
Power
2
EOC
End of conversion
Digital output
3
VDDA
Power supply
Power
4
VDDD
Digital power supply
Power
5
NC
no internal connection
-
6
SCL
2
I C serial bus clock input
2
Digital input
7
SDA
I C serial bus data
Digital bi-directional
8
XCLR
master clear (low active) input
Digital input
BST-BMP085-DS000-06 | Revision 1.3 | August 2011
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third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.
Note: Specifications within this document are subject to change without notice.
Data sheet
BMP085
Page 21
5.2 Outline dimensions
The sensor housing is a standard 8-pin lead-less chip carrier (LCC8) ceramic package. Its
dimensions are 5.0mm x 5.0mm (±0.25mm) x 1.2mm (±0.12mm).
Package weight is approximately 0.09grams.
Note: All dimensions are in mm.
5.2.1 Top view
Device pins are shown here transparently only for orientation purposes.
Figure 9: Top view
BST-BMP085-DS000-06 | Revision 1.3 | August 2011
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third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.
Note: Specifications within this document are subject to change without notice.
Data sheet
BMP085
Page 22
5.2.2 Top view with lid
Figure 10: Top view with lid
5.2.3 Side view with lid
Figure 11: Side view with lid
5.3 Device marking
The device lid shows the following laser-marking:
Pin 1 identifier
Date code
Bosch logo / vent hole / last 3 digits of part ID (TTN)
Lot ID
The vent hole (diameter 0.5mm) is in the center of the lid, between the Bosch logo and the part
ID code (144).
BST-BMP085-DS000-06 | Revision 1.3 | August 2011
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© Bosch Sensortec GmbH reserves all rights even in the event of industrial property rights. We reserve all rights of disposal such as copying and passing on to
third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.
Note: Specifications within this document are subject to change without notice.
Data sheet
BMP085
Page 23
5.4 Tape on reel
Number of parts per reel: 3,000
Orientation of the parts inside the reel is according to EN60286-3.
Carrier tape material: Conductive polystyrene C 100,
103 – 106 Ohm/sq.
Dimensions are in mm:
A0
B0
K0
P
W
t
=
=
=
=
=
=
5.30 ± 0.10
5.30 ± 0.10
2.10 ± 0.10
8.00 ± 0.10
12.00 +0.30 / -0.10
0.30 ± 0.05
The bars between the cavities are embossed about 0.2mm into the direction of K0. All other
dimensions and tolerances follow the EIA 481 standard.
BST-BMP085-DS000-06 | Revision 1.3 | August 2011
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© Bosch Sensortec GmbH reserves all rights even in the event of industrial property rights. We reserve all rights of disposal such as copying and passing on to
third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.
Note: Specifications within this document are subject to change without notice.
Data sheet
BMP085
Page 24
5.5 Printed circuit board (PCB) design
Figure 12: Recommended PCB design (top view)
5.6 Moisture sensitivity level and soldering
The BMP085 is classified MSL 1 (moisture sensitivity level) according to IPC/JEDEC standards
J-STD-020D and J-STD-033A.
The device can be soldered Pb-free with a peak temperature of 260°C for 20 to 40 sec. The
minimum height of the solder after reflow shall be at least 50μm. This is required for good
mechanical decoupling between the sensor device and the printed circuit board (PCB).
The BMP085 devices have to be soldered within 6 months after shipment (shelf life). To ensure
good solder-ability, the devices shall be stored at room temperature (20°C).
The soldering process can lead to an offset shift of typically 1hPa.
BST-BMP085-DS000-06 | Revision 1.3 | August 2011
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© Bosch Sensortec GmbH reserves all rights even in the event of industrial property rights. We reserve all rights of disposal such as copying and passing on to
third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.
Note: Specifications within this document are subject to change without notice.
Data sheet
BMP085
Page 25
5.7 RoHS compliancy
The BMP085 sensor meets the requirements of the EC directive "Restriction of hazardous
substances (RoHS)", please refer also to:
"Directive 2002/95/EC of the European Parliament and of the Council of 27 January 2003 on the
restriction of the use of certain hazardous substances in electrical and electronic equipment".
The BMP085 sensor is also halogen-free. Please contact your Bosch Sensortec representative
for the corresponding analysis report.
5.8 Mounting and assembly recommendations
Please read the following recommendations carefully.
•
The clearance above the metal lid shall be 0.1mm at minimum
•
For the device housing appropriate venting needs to be provided in case the ambient
pressure shall be measured; if waterproof packaging is needed, venting can be
accomplished by a vent element with a membrane like Gore-Tex(TM)
•
Liquids shall not come into direct contact with the device
•
During operation the sensor is sensitive to light, which can influence the accuracy of the
measurement (photo-current of silicon); therefore, the hole in the top lid shall not be
exposed to direct light during operation
•
The BMP085 shall not the placed close the fast heating parts. In case of gradients
> 3°C/sec. it is recommended to follow Bosch Sensortec application note ANP015,
"Correction of errors induced by fast temperature changes"; please contact your Bosch
Sensortec representative for details
•
For further details, please refer to the BMP085 handling, soldering & mounting
instructions manual that is also available from Bosch Sensortec
BST-BMP085-DS000-06 | Revision 1.3 | August 2011
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© Bosch Sensortec GmbH reserves all rights even in the event of industrial property rights. We reserve all rights of disposal such as copying and passing on to
third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.
Note: Specifications within this document are subject to change without notice.
Data sheet
BMP085
Page 26
6. Legal disclaimer
6.1 Engineering samples
Engineering Samples are marked with an asterisk (*) or (e) or (E). Samples may vary from the
valid technical specifications of the product series contained in this data sheet. They are
therefore not intended or fit for resale to third parties or for use in end products. Their sole
purpose is internal client testing. The testing of an engineering sample may in no way replace
the testing of a product series. Bosch Sensortec assumes no liability for the use of engineering
samples. The Purchaser shall indemnify Bosch Sensortec from all claims arising from the use of
engineering samples.
6.2 Product use
Bosch Sensortec products are developed for the consumer goods industry. They may only be
used within the parameters of this product data sheet. They are not fit for use in life-sustaining
or security sensitive systems. Security sensitive systems are those for which a malfunction is
expected to lead to bodily harm or significant property damage. In addition, they are not fit for
use in products which interact with motor vehicle systems.
The resale and/or use of products are at the purchaser’s own risk and his own responsibility.
The examination of fitness for the intended use is the sole responsibility of the Purchaser.
The purchaser shall indemnify Bosch Sensortec from all third party claims arising from any
product use not covered by the parameters of this product data sheet or not approved by Bosch
Sensortec and reimburse Bosch Sensortec for all costs in connection with such claims.
The purchaser must monitor the market for the purchased products, particularly with regard to
product safety, and inform Bosch Sensortec without delay of all security relevant incidents.
6.3 Application examples and hints
With respect to any examples or hints given herein, any typical values stated herein and/or any
information regarding the application of the device, Bosch Sensortec hereby disclaims any and
all warranties and liabilities of any kind, including without limitation warranties of noninfringement of intellectual property rights or copyrights of any third party. The information given
in this document shall in no event be regarded as a guarantee of conditions or characteristics.
They are provided for illustrative purposes only and no evaluation regarding infringement of
intellectual property rights or copyrights or regarding functionality, performance or error has
been made.
BST-BMP085-DS000-06 | Revision 1.3 | August 2011
Bosch Sensortec
© Bosch Sensortec GmbH reserves all rights even in the event of industrial property rights. We reserve all rights of disposal such as copying and passing on to
third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.
Note: Specifications within this document are subject to change without notice.
Data sheet
BMP085
Page 27
7. Document history and modifications
Rev. No
0.1
0.2
0.3
1.0
1.1
1.2
1.3
Chapter Description of modifications/changes
First edition for description of serial production
material
Noise data update, peak current added, several minor
changes
1
Update peak current, typo correction
1
Changed VDDA to VDD and VDDD to VDDIO
3.5
Updated flow diagram
4
New comment on floating XCLR
4.1
Added details on start-up time
5.2
Added package weight
1
Absolute accuracy at -20°C added
2
Updated storage temperature
3.2
Added optional EOC to schematic
5.7
BMP085 is halogen-free
3.3
Added comment on noise data calculation
3.5
Variable type of B7 is unsigned long
Added comment on low active master clear and
4
120kOhms pull-up resistor
Added solution to connect two devices BMP085 to
4.2
the same I2C bus.
4.4
Added remark about automatic standby-mode
5.6
JEDEC J-STD-020D
5.5
Updated or recommended PCB-design picture
5.8
Explained that light sensitivity is only during operation
3.5
Added comment on availability of the ref. source code
All
Document format change only
Date
2008-02-19
2008-04-21
2008-04-21
2008-04-21
2008-04-21
2008-04-21
2008-04-21
2008-07-01
2008-07-01
2008-07-01
2008-07-01
2009-04-06
2009-10-15
2011-08-22
Bosch Sensortec GmbH
Gerhard-Kindler-Strasse 8
72770 Reutlingen / Germany
[email protected]
www.bosch-sensortec.com
Modifications reserved | Printed in Germany
Specifications subject to change without notice
Document number: BST-BMP085-DS000-06
Revision_1.3_082011
BST-BMP085-DS000-06 | Revision 1.3 | August 2011
Bosch Sensortec
© Bosch Sensortec GmbH reserves all rights even in the event of industrial property rights. We reserve all rights of disposal such as copying and passing on to
third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.
Note: Specifications within this document are subject to change without notice.