THS1040

SLAS290C − OCTOBER 2001 − REVISED OCTOBER 2004

19

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PRINCIPLES OF OPERATION

onboard reference generator configuration

The internal bandgap reference A1 can provide a supply-voltage-independent and temperature-independent

voltage on pin VREF.

External connections to REFSENSE control A1’s output to the VREF pin as shown in Table 1.

Table 1. Effect of REFSENSE Connection on VREF Value

REFSENSE CONNECTION

A1 OUTPUT TO VREF

SEE:

VREF pin

0.5 V

Figure 25

AGND

1 V

Figure 26

External divider junction

(1 + Ra/Rb)/2 V

Figure 27

AVDD

Open circuit

Figure 28

REFT

+

AV

DD

2

) VREF

2

REFB

+

AV

DD

2

* VREF

2

REFT–REFB

+ VREF

_

+

_

+

VBG

ADC

References

Buffer A2

MODE =

REFSENSE

0.1

µF 1 µF

AGND

VREF = 0.5 V

AVDD

2

or AVDD

Figure 25. 0.5-V VREF Using the Internal Bandgap Reference A1

(9)

(10)

(11)