TSC101 Parameter definitions
Doc ID 13313 Rev 3 11/18
4 Parameter definitions
4.1 Common mode rejection ratio (CMR)
The common-mode rejection ratio (CMR) measures the ability of the current-sensing
amplifier to reject any DC voltage applied on both inputs V
p
and V
m
. The CMR is referred
back to the input so that its effect can be compared with the applied differential signal. The
CMR is defined by the formula:
4.2 Supply voltage rejection ratio (SVR)
The supply-voltage rejection ratio (SVR) measures the ability of the current-sensing
amplifier to reject any variation of the supply voltage V
CC
. The SVR is referred back to the
input so that its effect can be compared with the applied differential signal. The SVR is
defined by the formula:
4.3 Gain (Av) and input offset voltage (V
os
)
The input offset voltage is defined as the intersection between the linear regression of the
V
out
versus V
sense
curve with the X-axis (see Figure 20). If V
out1
is the output voltage with
V
sense
=V
sense1
=50mV and V
out2
is the output voltage with V
sense
=V
sense2
=5mV, then V
os
can be calculated with the following formula:
The amplification gain A
v
is defined as the ratio between output voltage and input differential
voltage:
CMR 20–
ΔV
out
ΔV
icm
Av⋅
------------------------------log⋅=
SVR 20–
ΔV
out
ΔV
CC
Av⋅
------------------------------log⋅=
V
os
V
sense1
V
sense1
V
sense2
–
V
out1
V
out2
–
------------------------------------------------
V
out1
⋅
⎝⎠
⎛⎞
–=
Av
V
out
V
sense
------------------=
