When the input common-mode voltage is higher than 40% of the VCC, the amplifier A2 is active. An Iload current

flowing into the shunt generates Vsense, a small differential voltage between TSC20x’s input pins. Due to the A2

amplifier, a current Ir flows through the input pin IN+. This current Ir is equal to Vsense/5 kΩ and is converted

through R2, into the voltage V2 as described in equation 1.

V2=2.5*Vsense

(1)

It is finally amplified by the A3 amplifier.

Vout=V2*A3

(2)

In case of TSC200 A3 = 8

In case of TSC201 A3 = 20

In case of TSC202 A3 = 40

The input bias current of IN+ is composed of the supply current of the input stage (roughly 30 µA), as well as Ir.

The value of Ir is directly linked to the sensing voltage Vsense. Figure 30 shows the sum of bias current into the

input pins.

Figure 30. Input bias current vs. Vsense for a Vicm = 80 V

0

100

200

300

400

500

600

0

100

200

300

400

500

600

-25

0

25

50

75

100

125

150

175

200

-25

0

25

50

75

100

125

150

175

200

Iibp

Vcc=12V

Vicm=80V

T=25°C

Iibn

Vsense (mV)

Mode 2: Vsense > 20 mV and Vicm < 40% VCC

Figure 31 depicts a simplified diagram, explaining the main functional principle of TSC20x for the mode 2

operation.

TSC200, TSC201, TSC202

Theory of operation

DS13882 - Rev 2

page 13/34