C8051F709-GQR Silicon Labs, C8051F709-GQR Datasheet - Page 58

• Manufacturer Part Number: C8051F709-GQR
• Description: 8-bit Microcontrollers - MCU 8kB 32B EEPROM Cap Sense
• Manufacturer: Silicon Labs

Specifications of C8051F709-GQR

• Rohs: yes
• Core: 8051
• Processor Series: C8051
• Data Bus Width: 8 bit

C8051F70x/71x
10.3.3. Settling Time Requirements
A minimum tracking time is required before each conversion to ensure that an accurate conversion is per-
formed. This tracking time is determined by any series impedance, including the AMUX0 resistance, the
the ADC0 sampling capacitance, and the accuracy required for the conversion. In delayed tracking mode,
three SAR clocks are used for tracking at the start of every conversion. For many applications, these three
SAR clocks will meet the minimum tracking time requirements.
Figure 10.3 shows the equivalent ADC0 input circuit. The required ADC0 settling time for a given settling
accuracy (SA) may be approximated by Equation 10.1. See Table 9.10 for ADC0 minimum settling time
requirements as well as the mux impedance and sampling capacitor values.
Where:
SA is the settling accuracy, given as a fraction of an LSB (for example, 0.25 to settle within 1/4 LSB)
t is the required settling time in seconds
R
n is the ADC resolution in bits (10).
58
TOTAL
is the sum of the AMUX0 resistance and any external source resistance.
Note: See electrical specification tables for R
Input Pin
Equation 10.1. ADC0 Settling Time Requirements
Figure 10.3. ADC0 Equivalent Input Circuits
t
=
RC
MUX Select
ln
Input


------ -
SA
= R
2
n


MUX

* C
Rev. 1.0
R
R
TOTAL
SAMPLE
MUX
C
SAMPLE
MUX
and C
C
SAMPLE
SAMPLE
parameters.