THS1030_13 Datasheet, PDF (19/39 Pages) Texas Instruments – 3-V TO 5.5-V, 10-BIT, 30MSPS CMOS ANALOG-TO-DIGITAL CONVERTER

THS1030
3ĆV TO 5.5ĆV, 10ĆBIT, 30 MSPS
CMOS ANALOGĆTOĆDIGITAL CONVERTER
SLAS243E − NOVEMBER 1999 − REVISED DECEMBER 2003
PRINCIPLES OF OPERATION
onboard reference generator configuration
The onboard reference generator (ORG) can provide a supply-voltage-independent and temperature-
independent voltage on pin VREF.
External connections to REFSENSE control the ORG’s output to the VREF pin as shown in Table 2.
Table 2. Effect of REFSENSE Connection on VREF Value
REFSENSE CONNECTION
VREF pin
AGND
External divider junction
AVDD
ORG OUTPUT TO VREF
1V
2V
(1 + RA/RB)
Open circuit
REFER TO:
Figure 20
Figure 21
Figure 22
Figure 23
REFSENSE = AV_DD powers the ORG down, saving power when the ORG function is not required.
If MODE = AV_DD/2, the voltage on VREF determines the ADC reference voltages:
REFTF
+
AVDD
2
)
VREF
2
(6)
REFBF
+
AVDD
2
*
VREF
2
REFTF * REFBF + VREF
VBG
+
_
Internal
Reference
Buffer
Mode =
AVDD
2
+
_
VREF = 1 V
REFSENSE
0.1 µF 1 µF
Tantalum
AGND
Figure 20. 1-V VREF Using ORG
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