TLC876M, TLC876I, TLC876C

10-BIT 20 MSPS PARALLEL OUTPUT CMOS

ANALOG-TO-DIGITAL CONVERTERS

SLAS140E – JULY 1997 – REVISED OCTOBER 2000

18

POST OFFICE BOX 655303

PRINCIPLES OF OPERATION

ac considerations

(continued)

_

+

5 V

C3

0.1

µF

_

+

C4

0.1

µF

C1

0.1

µF

REFT

REFB

REFTS

REFTF

REFBS

REFBF

TLC876

C2

0.1

µF

Figure 20. Kelvin Connection Reference Using an Operational Amplifier

With Unlimited Capacitive Load Drive Capability

Figure 21 shows a circuit using a dual operational amplifier with unlimited capacitive load drive. The operational

amplifier should provide stable 3.6 V and 1.6 V reference voltages for REFTF and REFBF, respectively. The

amplifier must be able to maintain stability while driving unlimited capacitive loads, so the 0.1

µF capacitors C1

and C2 can connect directly to the outputs of the operational amplifiers, which reduces high frequency

transients. Capacitors C3 and C4 shunt across the internal resistors of the force-sense connections and prevent

instability. The stability of any operational amplifier used must be examined closely when driving capacitive

loads.

_

+

1

µF

_

+

REFT

REFB

REFTS

REFTF

REFBS

REFBF

TLC876

0.1

µF

1

µF

0.1

µF

10 k

Ω

10

Ω

10 k

Ω

10

Ω

A†

† This device is 1/2 of a TLV2442. The TLV2442 is a rail-to-rail output dual operational

amplifier.

A†

10 k

Ω

0.1

µF

10 k

Ω

0.1

µF

Figure 21. Kelvin Connection Reference Using an Operational Amplifier

With Unlimited Capacitive Load Drive Capability