lmp7312max National Semiconductor Corporation, lmp7312max Datasheet - Page 19

• Manufacturer Part Number: lmp7312max
• Description: Lmp7312 Precision Spi-programmable Afe With Differential/single-ended Input/output
• Manufacturer: National Semiconductor Corporation

Noise calculation
Listed in the table below are the calculated values for Voltage
Noise based on the spectral density of the core op-amp at
10kHz (for all gain configurations).
Input resistance calculation
The common mode input resistance is the resistance seen
from node “A” when ΔV1 = ΔV2 = 0 and a common mode
voltage ΔVCM is applied to both inputs of the LMP7312. The
Gain
Total Noise Referred to Input
Total Noise Referred to Output
Gain
Total Offset Input Referred (MAX)
Total Offset Output Referred (MAX)
TCV
TCV
OS
OS
Output Referred @ 25°C (MAX)
Mode of Operation
Attenuation Mode
Amplification Mode
Input Referred @ 25°C (MAX)
Parameter
Parameter
Common Mode Resistance
Differential Resistance
Common Mode Resistance
Differential Resistance
FIGURE 9. Circuit for Input Resistance calculation
nV/
nV/
µV/°C
µV/°C
Unit
Unit
V/V
V/V
µV
µV
±1141
0.096
0.096
±32.3
±109
±3.3
211
20
19
differential input resistance is the resistance seen from the
nodes “B” and “C” when ΔVCM=0 and a differential voltage
ΔV1 = ΔV2 = V/2 is applied to the inputs of the LMP7312.
0.192
0.192
±18.6
±620
±119
±3.6
150
29
Unit
kΩ
kΩ
kΩ
kΩ
Value
Value
0.384
0.384
±10.8
±360
±138
±4.1
228.30
112
0.096
57.08
43
30075508
160.0
40.0
1
248.30
0.192
62.08
0.768
0.768
±230
±176
±6.9
±5.3
89
68
Gains
288.30
0.384
72.08
±200
±200
±6
±6
240.0
53
53
60.0
1
1
2
368.30
0.768
92.08
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±150
±300
±4.5
±9
46
92
2
2