XC68HC12A0CPV8 Freescale Semiconductor, XC68HC12A0CPV8 Datasheet - Page 353

• Manufacturer Part Number: XC68HC12A0CPV8
• Description: IC, 16BIT MCU, 68HC12, 8MHZ, TQFP-112
• Manufacturer: Freescale Semiconductor

Specifications of XC68HC12A0CPV8

• Controller Family/series: 68HC12
• No. Of I/o's: 68
• Eeprom Memory Size: 1KB
• Ram Memory Size: 2KB
• Cpu Speed: 8MHz
• No. Of Timers: 1
• Core Size: 16 Bit
• Program Memory Size: 60KB
• Peripherals: ADC
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

18.4.3 Sample and Hold Stage
18.4.4 Analog-to-Digital Converter Submodule
18.4.5 Clock Prescaler Function
MC68HC912D60A — Rev. 3.1
Freescale Semiconductor
A Sample and Hold (S/H) stage accepts the analog signal from the input
multiplexer and stores it as a capacitor charge on a storage node in the
module. The sample process uses a three stage approach:
This charge redistribution method eliminates the need for external
sample-and-hold circuitry.
The Analog-to-Digital (A/D) Machine uses a successive approximation
A/D architecture to perform analog to digital conversions. The resolution
of the A/D converter is selectable at either 8 or 10 bits. It functions by
comparing the stored analog sample potential with a series of digitally
generated analog potentials (using CDAC & RDAC arrays). By following
a binary search algorithm, the converter quickly locates the
approximating potential that is nearest to the sampled potential. At the
end of the conversion process (10 module clocks for 8-bit, 12 module
clocks for 10-bit), the Successive Approximation Register (SAR)
contains the nearest approximation to the sampled signal, given the
resolution of the A/D converter, and is transferred to the appropriate
results register in the selected format.
To keep the ATD module clock within the specified frequency range
(note: there is a minimum and maximum frequency), a clock prescaler
function is available. This function divides the system PCLK by a
1. The input signal is sampled onto a sample capacitor (for 2 module
2. The sample amplifier quickly charges the storage node with a
3. The input signal is connected directly to the storage node to
clocks).
copy of the sample capacitor potential (for 4 module clocks).
complete the sample for high accuracy (for 2, 4, 8 or 16 module
clocks). Longer sample times allow accurate measurement of
higher impedance sources.
Analog-to-Digital Converter
Analog-to-Digital Converter
Functional Description
Technical Data
353