DA6503.005
14 December 2016
APPLICATION INFORMATION
Input Signal Range Definitions
The input signal voltage polarity is from positive input PI to the negative input NI. MAS6503 has input signal
range (ISR) and offset (OFFSET) selection options that determines the input signal range of the A/D converter.
The minimum and maximum input signal values in the linear input signal range (ISRLIN) are calculated as
follows. Due to ratiometric principle the input signal range is directly proportional to VDD.
VDD
2.7V
VDD
2.7V
ISRLIN
VIN _ MIN
VIN _ MAX
OFFSET
Equation 1.
2
ISRLIN
2
OFFSET
Equation 2.
Table 13 shows minimum and maximum input signal values in the linear input signal range at different input
signal range and offset selection combinations.
Table 13. Examples of minimum and maximum input signal values in the linear input signal range (Vdd=2.7V)
OFFSET
[mV]
ISR
[mV]
ISRLIN
[mV]
VIN_MIN
[mV]
VIN_MAX
[mV]
0
126
0
86
0
57
0
40
373
373
253
253
172
172
115
115
298
298
202
202
138
138
92
-149
-23
-101
-15
-69
-12
-46
-6
149
275
101
187
69
126
46
86
92
The digital A/D conversion result, CODE, depends on the input signal as follows.
VIN OFFSET
CODE CODEFS 0.5
Equation 3.
ISR
CODE = digital A/D-conversion output code
CODEFS = A/D-converter maximum code (minimum code is zero)
See page 4 Electrical Characteristics for CODEFS values at different over sampling ratio (OSR) selections.
Pressure Measurement Configuration
A piezoresistive absolute pressure sensor can be modeled roughly with the following signal voltage
characteristic when including only first order pressure and temperature characteristics.
FS
1TCFS
T TREF
VDD
VIN
p,T
p OS
1TCOS
T TREF
Equation 4.
VDDREF
pFS
VDD = supply voltage
TCFS = full-scale span temperature coefficient
[ppm/C]
TCOS = offset temperature coefficient [ppm/C]
TREF = reference temperature for resistor values
[C]
VDDREF = reference supply voltage at which the
sensor parameters (FS, OS) have been specified
(often 5V)
p = pressure [bar]
pFS = full-scale pressure range [bar]
FS = full-scale span [V]
T = actual temperature to be measured [C]
OS = zero pressure offset [V]
The above linear approximation includes sensor full-scale span and offset signal temperature dependencies.
25 (34)
MAS [ MICRO ANALOG SYSTEMS ]
