sm5812-100-s-5-l Servoflo Corporation, sm5812-100-s-5-l Datasheet - Page 2

• Manufacturer Part Number: sm5812-100-s-5-l
• Description: Amplified Pressure Sensor
• Manufacturer: Servoflo Corporation

40SP5004.01
THEORY OF OPERATION
The operation of the signal processor is
depicted in the block diagram below. The
external pressure sensor is a piezoresistive
bridge. This transduces the applied
pressure into an electronic signal, which
feeds into the integrated amplifier of the
ASIC.
During the amplification step an offset
correction factor is added in order to allow
maximum gain for a given pressure while
minimizing the offset error.
The signal is then passed to an 11-bit
analog to digital converter (ADC). The ADC
samples the signal multiple times and uses
the sum of those samples as a 13-bit word.
A digital signal processor (DSP) is then used
to correct and calibrate the pressure signal.
The DSP provides multi-order correction of
both pressure and temperature non-linearity
through the use of factory-programmed
12_08
Piezoresistive
+ 5 VDC
External
Ground
Bridge
Tel: [phone] ♦ Fax: [phone] ♦ [e-mail] ♦ www.si-micro.com
Silicon Microstructures, Inc. ♦ 1701 McCarthy Blvd. ♦ Milpitas, CA 95035 USA
SMI Multi-Order Pressure and
Temperature Correction ASIC
Power-On
Reset
Integrateing
Band-gap
Capacitor
Switched
Amplifier
Oscillator
Control
Analog
Timing
V
2 MHz
Temp
Amplified Pressure Sensor
MUX
+ 5 VDC
Ground
coefficients. A combined total of twenty
coefficients are available for correcting
pressure and temperature non-linearity. The
unique coefficients are determined during a
calibration process performed at the factory.
Factory calibration is the last step performed
which means the effect of the package on
the pressure signal will also be taken into
account. This provides a great advantage
over conventional laser-trimming
approaches.
The DSP outputs a corrected digital word,
which travels to a 12-bit digital to analog
converter (DAC) to provide a calibrated
analog output. In addition to the analog
output, the corrected pressure signal is
accessible through an I
See SMI application note AN05-001 for a
detailed description of how to read out the
digital corrected pressure signal using the
I2C bus interface.
Digital Timing
11-bit ADC
Management
and Control
EEPROM
Array
pressure and
correction of
temperature
(multi-order
linearities)
non-
DSP
2
C digital interface.
Analog Component
Digital Component
Delta DAC
I
2
Interface
Sigma-
Output
C Digital
Buffer
12-bit
SM5852
Analog
Output
SDA
SCL