TLC5540

SLAS105D − JANUARY 1995 − REVISED APRIL 2004

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13

PRINCIPLES OF OPERATION

internal reference voltage conversion

Three internal resistors allow the device to generate an internal reference voltage. These resistors are brought

without the use of external resistors.

Internal resistors are provided to develop REFT = 2.6 V and REFB = 0.6 V (bias option one) with only two

connect REFT to REFTS and connect REFB to REFBS. For applications where the variance associated with

A second internal bias option (bias two option) is shown in Figure 15. Using this scheme REFB = AGND and

REFT = 2.28 V nominal. These bias voltage options can be used to provide the values listed in the following

table.

Table 1. Bias Voltage Options

BIAS OPTION

BIAS VOLTAGE

BIAS OPTION

VRB

VRT

VRT − VRB

1

0.61

2.63

2.02

2

AGND

2.28

2.28

To use the internally-generated reference voltage, terminal connections should be made as shown in

Figure 14 or Figure 15. The connections in Figure 14 provide the standard video 2-V reference.

R1

320

Ω NOM

Rref

270

Ω NOM

R2

80

Ω NOM

VDDA

5 V (Analog)

REFTS

REFT

REFB

REFBS

AGND

TLC5540

16

17

22

21

23

18

0.1

µF

0.1

µF

2.63 V dc

0.61 V dc

Figure 14. External Connections Using the Internal Bias One Option