C8051F530-IMR Silicon Labs, C8051F530-IMR Datasheet - Page 61

• Manufacturer Part Number: C8051F530-IMR
• Description: 8-bit Microcontrollers - MCU 8KB 12ADC 125C
• Manufacturer: Silicon Labs

Specifications of C8051F530-IMR

• Product Category: 8-bit Microcontrollers - MCU
• Rohs: yes
• Core: 8051
• Data Bus Width: 8 bit
• Maximum Clock Frequency: 25 MHz
• Program Memory Size: 8 KB
• Data Ram Size: 256 B
• On-chip Adc: Yes
• Package / Case: QFN EP
• Mounting Style: SMD/SMT
• A/d Bit Size: 12 bit
• A/d Channels Available: 16
• Interface Type: SPI, UART
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 40 C
• Number Of Programmable I/os: 16
• Number Of Timers: 3
• On-chip Dac: No
• Processor Series: C8051
• Program Memory Type: Flash
• Factory Pack Quantity: 1500
• Supply Voltage - Max: 2.7 V, 5.25 V
• Supply Voltage - Min: 2 V, 2.7 V

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
1
–
GAINADD Value





1 (default)
----- -
64
1
+
Rev. 1.4


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
C8051F52x/F53x
4096


=
1.0
Equivalent Gain
1.0 (default)
1.016
0.75
0.25
~1.0
0.5
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