C8051F020DK Silicon Laboratories Inc, C8051F020DK Datasheet - Page 78

• Manufacturer Part Number: C8051F020DK
• Description: DEV KIT FOR F020/F021/F022/F023
• Manufacturer: Silicon Laboratories Inc
• Type: MCUr

Specifications of C8051F020DK

• Contents: Evaluation Board, Power Supply, USB Cables, Adapter and Documentation
• Processor To Be Evaluated: C8051F02x
• Interface Type: USB
• Silicon Manufacturer: Silicon Labs
• Core Architecture: 8051
• Silicon Core Number: C8051F020
• Silicon Family Name: C8051F02x
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• For Use With/related Products: Silicon Laboratories C8051 F020/021/022/023
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 336-1200

C8051F020/1/2/3
7.2.3. Settling Time Requirements
When the ADC1 input configuration is changed (i.e., a different MUX or PGA selection), a minimum settling (or
tracking) time is required before an accurate conversion can be performed. This settling time is determined by the
ADC1 MUX resistance, the ADC1 sampling capacitance, any external source resistance, and the accuracy required
for the conversion. Figure 7.3 shows the equivalent ADC1 input circuit. The required ADC1 settling time for a given
settling accuracy (SA) may be approximated by Equation 7.1. Note that in low-power tracking mode, three SAR1
clocks are used for tracking at the start of every conversion. For most applications, these three SAR1 clocks will meet
the tracking requirements. See Table 7.1 for absolute minimum settling time requirements.
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 tracking time in seconds
R
n is the ADC resolution in bits (8).
78
TOTAL
is the sum of the ADC1 MUX resistance and any external source resistance.
Equation 7.1. ADC1 Settling Time Requirements
Figure 7.3. ADC1 Equivalent Input Circuit
AIN1.x
t
=
RC
ln
MUX Select
Input


= R
------ -
SA
2
n
MUX


Rev. 1.4

R
* C
MUX
R
SAMPLE
TOTAL
= 5k
C
SAMPLE
C
SAMPLE
= 10pF