C8051F530-TB Silicon Laboratories Inc, C8051F530-TB Datasheet - Page 61

• Manufacturer Part Number: C8051F530-TB
• Description: BOARD PROTOTYPE W/C8051F530
• Manufacturer: Silicon Laboratories Inc
• Type: MCUr

Specifications of C8051F530-TB

• Contents: Board
• Processor To Be Evaluated: C8051F52xA and C8051F53xA
• Interface Type: USB
• Lead Free Status / RoHS Status: Vendor undefined / Vendor undefined
• For Use With/related Products: C8051F530
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

4.4.1. Calculating the Gain Value
The ADC0 selectable gain feature is controlled by 13 bits in three registers. ADC0GNH contains the 8
upper bits of the gain value and ADC0GNL contains the 4 lower bits of the gain value. The final GAINADD
bit (ADC0GNA.0) controls an optional extra 1/64 (0.016) of gain that can be added in addition to the
ADC0GNH and ADC0GNL gain. The ADC0GNA.0 bit is set to 1 after a power-on reset.
The equivalent gain for the ADC0GNH, ADC0GNL and ADC0GNA registers is:
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
For example, if ADC0GNH = 0xFC, ADC0GNL = 0x00, and GAINADD = '1', GAIN = 0xFC0 = 4032, and
the resulting equation is:
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:
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.
ADC0GNH Value
Equation 4.3. Calculating the ADC0GNH and ADC0GNL Values from the Desired Gain
0xFC (default)
0xBC
0x7C
0x3C
0xFF
0xFF
Equation 4.2. Equivalent Gain from the ADC0GNH and ADC0GNL Registers
gain
ADC0GNL Value
0x00 (default)
GAIN
=
gain
0xF0
0xF0
0x00
0x00
0x00


4032
----------- -
4096
=
=


gain GAINADD




GAIN
-------------- -
+
4096
C8051F52x/F52xA/F53x/F53xA
1
–
GAINADD Value





1 (default)
----- -
64
1
+
Rev. 1.3


GAINADD
1
1
1
0
1
=
0.984



----- -
64
+
1



0.016




----- -
64
GAIN Value

1
4032 + 64
1984 + 64
3008 + 64
4095 + 64
960 + 64
4095 + 0
4096


=
1.0
Equivalent Gain
1.0 (default)
1.016
0.75
0.25
~1.0
0.5
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