AMS 6916

Board mount pressure sensor with ratiometric analog output

April 2019

– Rev. 1.0, preliminary

Page 5/9

www.analog-micro.com

During AMS 6916

’s factory calibration sensor-specific correction coefficients are determined and stored in

each

sensor’s EEPROM. This permits sensor-specific calibration and correction (i.e. temperature

compensation and linearization) of the digitized pressure signal. The temperature signal necessary for

temperature compensation is generated at the ASIC

’s temperature reference block (TSig) and is transmitted

by the multiplexer to the ADC, where it is digitized. The ASIC

’s microcontroller block runs a cyclic program,

which continuously calculates the current standardized and corrected digital pressure value using the current

digitized pressure and temperature values as well as the stored correction coefficients.

Based on the linearized, temperature compensated and calibrated digital pressure value calculated by the

microcontroller, the 12-bit D/A converter (DAC) block generates a ratiometric analog output voltage signal,

which is factory calibrated to

0.5 … 4.5 V at 5 V supply voltage.

AMS 6916’s ideal output voltage VOUT

rat

at pin 1 (OUT) is a linear function of the applied pressure p and the

supply voltage VS .

It can be calculated by:

VOUT

rat (p, V

S) = (

p - pmin

pmax - pmin

∙0.8 + 0.1) ∙VS

(1)

Therein pmin and pmax are the sensor’s specified minimum and maximum pressure, given by the sensor’s

pressure range in Table 1. The applied measurement pressure p is defined by

p = p1 - p2

for differential and bi-directional types

p = p1

for relative types (with p1 referenced to ambient pressure)

p = p2

for absolute and barometric types (with p2 referenced to vacuum)

with the definition p1 = pressure at port 1 and p2 = pressure at port 2 of AMS 6915 (for port definition see

Figure 3).

Furthermore the output at pin 1 (OUT) is short circuit protected against GND and Vs.

AMS 6916’s diagnostic function

The AMS 6916 series has integrated diagnostic features to ensure that the sensor is working properly. The

proof of functionality is done by the signal conditioning ASIC

’s diagnostics block, which is able to detect the

following errors:

-

failures in EEPROM contents (checked after Power On)

-

failures in the pressure sensing element

’s electrical connections (checked during measurement

operation)

-

failures in the sensor’s power or ground connection (Vs or GND loss, checked during measurement

operation).

If the diagnostics block detects an error, the output voltage is set to a value in the diagnostic range, with

VOUT ≤ 0.025 · Vs or VOUT ≥ 0.975 · Vs.