SmartFusion DC and Switching Characteristics
2-82 Revision 10
Analog Bipolar Prescaler (ABPS)
With the ABPS set to its high range setting (GDEC = 00), a hypothetical input voltage in the range –15.36
V to +15.36 V is scaled and offset by the ABPS input amplifier to match the ADC full range of 0 V to 2.56
V using a nominal gain of –0.08333 V/V. However, due to reliability considerations, the voltage applied to
the ABPS input should never be outside the range of –11.5 V to +14.4 V, restricting the usable ADC input
voltage to 2.238 V to 0.080 V and the corresponding 12-bit output codes to the range of 3581 to 128
(decimal), respectively.
Unless otherwise noted, ABPS performance is specified at 25°C with nominal power supply voltages,
with the output measured using the internal voltage reference with the internal ADC in 12-bit mode and
100 KHz sampling frequency, after trimming and digital compensation; and applies to all ranges.
Table 2-97 • ABPS Performance Specifications
Specification Test Conditions Min. Typ. Max. Units
Input voltage range (for driving ADC
over its full range)
GDEC[1:0] = 11 ±2.56 V
GDEC[1:0] = 10 ±5.12 V
GDEC[1:0] = 01 ±10.24 V
GDEC[1:0] = 00 (limited by
maximum rating)
See note 1 V
Analog gain (from input pad to ADC
input)
GDEC[1:0] = 11 –0.5 V/V
GDEC[1:0] = 10 –0.25 V/V
GDEC[1:0] = 01 –0.125 V/V
GDEC[1:0] = 00 –0.0833 V/V
Gain error –2.8 –0.4 0.7 %
–40ºC to +100ºC –2.8 –0.4 0.7 %
Input referred offset voltage
GDEC[1:0] = 11 –0.31 –0.07 0.31 % FS*
–40ºC to +100ºC –1.00 1.47 % FS*
GDEC[1:0] = 10 –0.34 –0.07 0.34 % FS*
–40ºC to +100ºC –0.90 1.37 % FS*
GDEC[1:0] = 01 –0.61 –0.07 0.35 % FS*
–40ºC to +100ºC –1.05 1.35 % FS*
GDEC[1:0] = 00 –0.39 –0.07 0.35 % FS*
–40ºC to +100ºC –1.06 1.38 % FS*
SINAD 53 56 dB
Non-linearity RMS deviation from BFSL 0.5 % FS*
Note: *FS is full-scale error, defined as the difference between the actual value that triggers the transition to full-scale
and the ideal analog full-scale transition value. Full-scale error equals offset error plus gain error. Refer to the
Analog-to-Digital Converter chapter of the SmartFusion Programmable Analog User’s Guide for more
information.
