TS4994FC

Application information

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The two following graphs show typical applications of the TS4994 with a random selection of

four

4.6

CMRR performance

has no influence in the calculation of the CMRR.

We use the same kind of resistor (same tolerance) and

ΔR is the tolerance value in %.

The following CMRR equation is valid for frequencies ranging from DC to about 1kHz.

The CMRR equation is (

ΔR in %):

Example: With

ΔR = 1%, the minimum CMRR is -34dB.

This example is a worst case scenario where each resistor has extreme tolerance. Ut

illustrates the fact that for CMRR, good matching is essential.

As with the PSRR, due to self-generated noise, the TS4994 CMRR limitation is about

-110dB.

worst-case conditions (

ΔR=0.1%).

Figure 92.

PSRR vs. frequency with random

choice condition

Figure 93.

PSRR vs. frequency with random

choice condition

100

1000

10000

-140

-130

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

Cb=0.1

μF

Cb=1

μF

Cb=0

20k

20

Cb=0.47

μF

Vcc = 5V, Vripple = 200mVpp

Av = 1, Cin = 4.7

μF

ΔR/R ≤ 0.1%, RL ≥ 8Ω

Tamb = 25

°C, Inputs = Grounded

Frequency (Hz)

100

1000

10000

-140

-130

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

Cb=0.1

μF

Cb=1

μF

Cb=0

20k

20

Cb=0.47

μF

Vcc = 2.5V, Vripple = 200mVpp

Av = 1, Cin = 4.7

μF

ΔR/R ≤ 0.1%, RL ≥ 8Ω

Tamb = 25

°C, Inputs = Grounded

Frequency (Hz)

)

dB

(

)

R

10000

(

200

R

Log

20

CMRR

⎦

⎤

⎢

⎣

⎡

Δ

−

×

Δ

×

≤