C8051F302 Silicon Laboratories Inc, C8051F302 Datasheet - Page 37

• Manufacturer Part Number: C8051F302
• Description: IC 8051 MCU 8K FLASH 11MLP
• Manufacturer: Silicon Laboratories Inc
• Series: C8051F30xr

Specifications of C8051F302

• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 25MHz
• Connectivity: SMBus (2-Wire/I²C), UART/USART
• Peripherals: POR, PWM, Temp Sensor, WDT
• Number Of I /o: 8
• Program Memory Size: 8KB (8K x 8)
• Program Memory Type: FLASH
• Ram Size: 256 x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 3.6 V
• Data Converters: A/D 8x8b
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 11-VQFN
• Data Bus Width: 8 bit
• Data Ram Size: 256 B
• Interface Type: I2C, SMBus, UART
• Maximum Clock Frequency: 25 MHz
• Number Of Programmable I/os: 8
• Number Of Timers: 16 bit
• Operating Supply Voltage: 2.7 V to 3.6 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 8 bit
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -
• Lead Free Status / Rohs Status: No

5.3.3. Settling Time Requirements
When the ADC0 input configuration is changed (i.e., a different AMUX0 or PGA 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 accuracy 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 minimum tracking time requirements.
Figure 5.5 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 VDD with
respect to GND, R
ments.
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 (8).
TOTAL
is the sum of the AMUX0 resistance and any external source resistance.
P0.x
P0.y
TOTAL
RC
Differential Mode
MUX Select
MUX Select
Input
= R
reduces to R
MUX
Equation 5.1. ADC0 Settling Time Requirements
R
R
* C
MUX
MUX
Figure 5.5. ADC0 Equivalent Input Circuits
SAMPLE
= 5k
= 5k
Note: When the PGA gain is set to 0.5, C
t
MUX
=
. See Table 5.1 for ADC0 minimum settling time (track/hold time) require-
C
C
ln
SAMPLE
SAMPLE


------ -
SA
2
= 5pF
= 5pF
n


×
R
TOTAL
Rev. 2.3
C
P0.x
SAMPLE
Single-Ended Mode
SAMPLE
RC
C8051F300/1/2/3/4/5
MUX Select
Input
= R
= 3pF
MUX
R
* C
MUX
SAMPLE
= 5k
C
SAMPLE
= 5pF
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