C8051F330 Silicon Laboratories Inc, C8051F330 Datasheet - Page 40

• Manufacturer Part Number: C8051F330
• Description: IC 8051 MCU 8K FLASH 20MLP
• Manufacturer: Silicon Laboratories Inc
• Series: C8051F33xr

Specifications of C8051F330

• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 25MHz
• Connectivity: SMBus (2-Wire/I²C), SPI, UART/USART
• Peripherals: POR, PWM, Temp Sensor, WDT
• Number Of I /o: 17
• Program Memory Size: 8KB (8K x 8)
• Program Memory Type: FLASH
• Ram Size: 768 x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 3.6 V
• Data Converters: A/D 16x10b; D/A 1x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 20-QFN
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -

C8051F330/1, C8051F330D
5.3.3. Settling Time Requirements
When the ADC0 input configuration is changed (i.e., a different AMUX0 selection is made), a minimum
tracking time is required before an accurate conversion can be performed. This tracking time is determined
by the AMUX0 resistance, the ADC0 sampling capacitance, any external source resistance, and the accu-
racy required for the conversion. Note that in low-power tracking mode, three SAR clocks are used for
tracking at the start of every conversion. For most applications, these three SAR clocks will meet the mini-
mum tracking time requirements.
Figure 5.4 shows the equivalent ADC0 input circuits for both Differential and Single-ended modes. Notice
that the equivalent time constant for both input circuits is the same. The required ADC0 settling time for a
given settling accuracy (SA) may be approximated by Equation 5.1. When measuring the Temperature
Sensor output or
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 settling time in seconds
R
n is the ADC resolution in bits (10).
40
TOTAL
is the sum of the AMUX0 resistance and any external source resistance.
Px.x
Px.x
RC
V
Differential Mode
MUX Select
MUX Select
Input
DD with respect to GND, R
= R
MUX
R
R
* C
MUX
MUX
Equation 5.1. ADC0 Settling Time Requirements
SAMPLE
= 5k
= 5k
Figure 5.4. ADC0 Equivalent Input Circuits
t
=
C
C
ln
SAMPLE
SAMPLE


------ -
SA
2
= 5pF
= 5pF
n


TOTAL
×
Rev. 1.2
R
TOTAL
reduces to R
C
Px.x
SAMPLE
Single-Ended Mode
RC
MUX
MUX Select
Input
= R
. See Table 5.1 for ADC0 minimum
MUX
R
* C
MUX
SAMPLE
= 5k
C
SAMPLE
= 5pF