C8051F040-GQR Silicon Laboratories Inc, C8051F040-GQR Datasheet - Page 78

• Manufacturer Part Number: C8051F040-GQR
• Description: IC 8051 MCU 64K FLASH 100TQFP
• Manufacturer: Silicon Laboratories Inc
• Series: C8051F04xr

Specifications of C8051F040-GQR

• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 25MHz
• Connectivity: CAN, EBI/EMI, SMBus (2-Wire/I²C), SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, Temp Sensor, WDT
• Number Of I /o: 64
• Program Memory Size: 64KB (64K x 8)
• Program Memory Type: FLASH
• Ram Size: 4.25K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 3.6 V
• Data Converters: A/D 8x8b, 13x12b; D/A 2x10b, 2x12b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 100-TQFP, 100-VQFP
• For Use With: 336-1205 - DEV KIT FOR F040/F041/F042/F043
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -

C8051F040/1/2/3/4/5/6/7
6.3.3. Settling Time Requirements
A minimum tracking time is required before an accurate conversion can be performed. This tracking time is
determined by the ADC0 MUX resistance, the ADC0 sampling capacitance, any external source resis-
tance, and the accuracy required for the conversion. Figure 6.5 shows the equivalent ADC0 input circuits
for both Differential and Single-ended modes. Notice that the equivalent time constant for both input cir-
cuits is the same. The required settling time for a given settling accuracy (SA) may be approximated by
Equation 6.2. When measuring the Temperature Sensor output, R
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 tracking requirements. See Table 6.2 for absolute mini-
mum settling/tracking 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).
78
TOTAL
AIN0.x
AIN0.y
is the sum of the ADC0 MUX resistance and any external source resistance.
RC
Differential Mode
MUX Select
MUX Select
Input
= R
MUX
R
R
Equation 6.2. ADC0 Settling Time Requirements
* C
MUX
MUX
SAMPLE
= 5k
= 5k
Figure 6.5. ADC0 Equivalent Input Circuits
C
C
t
SAMPLE
SAMPLE
=
= 10pF
= 10pF
ln


------ -
SA
2
n


Rev. 1.5

R
TOTAL
AIN0.x
C
SAMPLE
TOTAL
Single-Ended Mode
RC
MUX Select
Input
reduces to R
= R
MUX
R
* C
MUX
SAMPLE
= 5k
MUX
. Note that in low-
C
SAMPLE
= 10pF