C8051F540-TB Silicon Laboratories Inc, C8051F540-TB Datasheet - Page 36

• Manufacturer Part Number: C8051F540-TB
• Description: BOARD PROTOTYPE W/C8051F540
• Manufacturer: Silicon Laboratories Inc
• Type: MCUr

Specifications of C8051F540-TB

• Contents: Board
• Processor To Be Evaluated: C8051F54x
• Processor Series: C8051F54x
• Interface Type: USB
• Operating Supply Voltage: 5 V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: C8051F54x
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 336-1672

C8051F54x
For example, if ADC0GNH = 0xFC, ADC0GNL = 0x00, and GAINADD = 1, GAIN = 0xFC0 = 4032, and the
resulting equation is as follows:
The table below equates values in the ADC0GNH, ADC0GNL, and ADC0GNA registers to the equivalent
gain using this equation.
For any desired gain value, the GAIN registers can be calculated by the following:
Where:
GAIN is the 12-bit word of ADC0GNH[7:0] and ADC0GNL[7:4]
GAINADD is the value of the GAINADD bit (ADC0GNA.0)
gain is the equivalent gain value from 0 to 1.016
When calculating the value of GAIN to load into the ADC0GNH and ADC0GNL registers, the GAINADD bit
can be turned on or off to reach a value closer to the desired gain value.
For example, the initial example in this section requires a gain of 0.44 to convert 5 V full scale to 2.2 V full
scale. Using Equation 5.3:
If GAINADD is set to 1, this makes the equation:
The actual gain from setting GAINADD to 1 and ADC0GNH and ADC0GNL to 0x6CA is 0.4399. A similar
gain can be achieved if GAINADD is set to 0 with a different value for ADC0GNH and ADC0GNL.
36
ADC0GNH Value
Equation 5.3. Calculating the ADC0GNH and ADC0GNL Values from the Desired Gain
0xFC (default)
0xBC
0x7C
0x3C
0xFF
0xFF
GAIN
=
GAIN


0.44 1
ADC0GNL Value
0x00 (default)
GAIN
GAIN
–
=
0x00
0x00
0x00
0xF0
0xF0



4032
------------ -
4096


=
=
----- -
64
1






gain GAINADD
0.44 GAINADD




+

4096
1
–
–
GAINADD Value



1 (default)
----- -
64
1
Rev. 1.1
=


1
1
1
0
1
0.424 4096
=
0.984







----- -
64
----- -
64
1
1
+






0.016


GAIN Value

4032 + 64
1984 + 64
3008 + 64
4096 + 64

960 + 64
4095 + 0
=
4096
4096
1738
=
1.0
=
0x06CA
Equivalent Gain
1.0 (default)
1.016
0.75
0.25
~1.0
0.5