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MC68HC05B6_13 Datasheet, PDF (283/302 Pages) Freescale Semiconductor, Inc – Microcontrollers
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I.2
A/D converter characteristics
Table I-3 A/D characteristics for 5V operation
(VDD = 5.0 Vdc ± 10%, VSS = 0 Vdc, TA = –40 to +85°C)
Characteristic
Parameter
Min
Max
Unit
Resolution
Number of bits resolved by the A/D
8
—
Bit
Max deviation from the best straight line through
Non-linearity
the A/D transfer characteristics
—
(VRH = VDD and VRL = 0V)
Quantization error Uncertainty due to converter resolution
—
± 0.5
LSB
± 0.5
LSB
Difference between the actual input voltage and
Absolute accuracy the full-scale equivalent of the binary code
—
output code for all errors
±1
LSB
Conversion range Analog input voltage range
VRL
VRH
V
VRH
Maximum analog reference voltage
VRL
VDD + 0.1
V
VRL
∆VR(1)
Minimum analog reference voltage
VSS – 0.1
VRH
V
Minimum difference between VRH and VRL
3
—
V
Total time to perform a single analog to digital
Conversion time
conversion
a. External clock (OSC1, OSC2)
b. Internal RC oscillator
—
32
tCYC
—
32
µs
Monotonicity
Conversion result never decreases with an
increase in input voltage and has no missing
codes
GUARANTEED
Zero input reading Conversion result when VIN = VRL
Full scale reading Conversion result when VIN = VRH
Sample acquisition
time
Analog input acquisition sampling
a. External clock (OSC1, OSC2)
b. Internal RC oscillator(2)
00
—
Hex
—
FF
Hex
—
12
tCYC
—
12
µs
Sample/hold
capacitance
Input capacitance on PD0/AN0–PD7/AN7
—
12
pF
Input leakage(3)
Input leakage on A/D pins PD0/AN0–PD7/AN7
VRL, VRH
—
—
1
µA
1
µA
(1) Performance verified down to 2.5V ∆VR, but accuracy is tested and guaranteed at ∆VR = 5V±10%.
(2) Source impedances greater than 10kΩ will adversely affect internal charging time during input sampling.
(3) The external system error caused by input leakage current is approximately equal to the product of R
source and input current. Input current to A/D channel will be dependent on external source impedance
(see Figure 8-2).
MC68HC05B6
Rev. 4.1
HIGH SPEED OPERATION
Freescale
I-3
15
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