Application Information

TS4994

23/31

With

∆R=1%, the minimum CMRR would be -53dB that give Voo=5.6mV and an maximum extra

consumption less than 700

µA.

This example is of a worst case scenario where each resistor has extreme tolerance and illustrates the

fact that for CMRR, good matching is essential.

As with the PSRR, due to self-generated noise, the TS4994 CMRR limitation would be about -110dB.

(

∆R=0.1%).

Figure 75. CMRR vs. frequency worst case

condition

Figure 76. CMRR vs. frequency worst case

condition

Figures 77 and 78 show CMRR versus frequency for a typical application with four 0.1% tolerances and

a random choice for them.

Figure 77. CMRR vs. frequency with random

choice condition

Figure 78. CMRR vs. frequency with random

choice condition

100

1000

10000

-60

-50

-40

-30

-20

-10

0

Cb=1

µF

Cb=0

20k

20

Vcc = 5V

Vic = 200mVpp

Av = 1, Cin = 470

µF

∆R/R = 0.1%, RL ≥ 8Ω

Tamb = 25

°C

Frequency (Hz)

100

1000

10000

-60

-50

-40

-30

-20

-10

0

Cb=1

µF

Cb=0

20k

20

Vcc = 2.5V

Vic = 200mVpp

Av = 1, Cin = 470

µF

∆R/R = 0.1%, RL ≥ 8Ω

Tamb = 25

°C

Frequency (Hz)

100

1000

10000

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

Cb=1

µF

Cb=0

20k

20

Vcc = 5V

Vic = 200mVpp

Av = 1, Cin = 470

µF

∆R/R ≤ 0.1%, RL ≥ 8Ω

Tamb = 25

°C

Frequency (Hz)

100

1000

10000

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

Cb=1

µF

Cb=0

20k

20

Vcc = 2.5V

Vic = 200mVpp

Av = 1, Cin = 470

µF

∆R/R ≤ 0.1%, RL ≥ 8Ω

Tamb = 25

°C

Frequency (Hz)