RHF1401_12 Datasheet, PDF (30/42 Pages) STMicroelectronics – Rad-hard 14-bit 30 Msps A/D converter

User manual
RHF1401
The OR pin should rise to 1 when the signal is out of range. However, when VREFP = 0.8 V,
VREFM = 0 V, and input voltage max = 1.6 V, the ADC may not read the maximum input
voltage due to the CMOS input transistor. Consequently, the OR pin does not rise to 1. To
avoid this situation occurring, it is recommended to limit the input amplitude to 1.5 V, VREFP
to 0.75 V, and VREFM to 0 V.
Figure 56. AC-coupling single-ended input configuration
50 Ω track
Cin
Short track
VIN
Analog input signal _{50 Ω}
(50 Ω output)
R
INCM
R
470 pF
ceramic*
Short track
100 nF
ceramic*
VINB
External INCM
(optional)
100 nF ceramic*
(as close as possible
to INCM pin)
*the use of a ceramic technology is
preferable for a large bandwidth
stability of the capacitor
AM04572
Figure 57. AC-coupling single-ended input configuration for low frequencies
50 Ω track
Analog input signal _{50 Ω}
(50 Ω output)
Cin
C
Short track
VIN
R
INCM
R
Short track
VINB
*ceramic technology for a large
bandwidth stability of the capacitor
External INCM
(optional)
100 nF ceramic*
(as close as possible
to INCM pin)
AM04573
The C capacitor is efficient in reducing noise at high frequencies. When coupled with the
resistors, R and C together behave like a high-pass filter. For example, if R = 10 k and
C = 33 pF, the cut-off frequency of this filter equals 482 kHz.
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Doc ID 13317 Rev 8