RHF1401_12 STMICROELECTRONICS [STMicroelectronics], RHF1401_12 Datasheet - Page 29

• Manufacturer Part Number: RHF1401_12
• Description: Rad-hard 14-bit 30 Msps A/D converter
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

RHF1401
3.2.2
Single-ended mode
Figure 55. Optimized single-ended configuration (DC coupling), external REFP
Table 13.
The RHF1401 is designed for use in a differential input configuration. Nevertheless, it can
achieve good performance in a single-ended input configuration. In single-ended,
performances depend on the input voltage, input frequency, voltage of references and
sampling frequency (refer to
VREFP and INCM internal voltage references are not adapted to Single-ended mode.
Some applications may require a single-ended input, which can easily be achieved with the
configuration shown in
However, with this type of configuration, a degradation in the rated performance of the
RHF1401 may occur compared with a differential configuration. A sufficiently decoupled DC
reference should be used to bias the RHF1401 inputs. An AC-coupled analog input can also
be used and the DC analog level set with a high value resistor R (6 k to 100 k ) connected
to a proper DC source. Cin and R behave like a high-pass filter and are calculated to set the
lowest possible cut-off frequency.
Each input is limited to about 1.6 V due to the CMOS transistor on the input path. Voltage
can be a bit more or less than 1.6 V depending on temperature, AVCC, and variations from
one die to another (see
independent of the VREFP and VREFM values.
INCM + (VREFP-VREFM)
INCM - (VREFP-VREFM)
0 V (ground)
INCM
Vin =
Single-ended mode output codes with Vinb = INCM
INCM
Figure
Figure 3
VIN
Figure 42.
56,
Doc ID 13317 Rev 8
VIN
for the analog input schematic). This “input limitation” is
Figure 57
to
DFSB = 1
Figure
3FFF
1FFF
0000
for AC coupling or
External
49.)
INCM
VINB
VIN
Figure 35.
External
INCM
REFP
REFM
DFSB = 0
for DC coupling.
1FFF
3FFF
Ground
2000
AM04569
User manual
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