mc9s08gt32a Freescale Semiconductor, Inc, mc9s08gt32a Datasheet - Page 229

• Manufacturer Part Number: mc9s08gt32a
• Description: Hcs08 Microcontrollers 8-bit Microcontroller Family
• Manufacturer: Freescale Semiconductor, Inc

There are two other forms of error which are not specified which can also affect ATD accuracy. These are:
Freescale Semiconductor
•
•
•
•
•
Full scale error (E
and the ideal transition to that code. Normally, it is defined as the difference between the actual and
ideal transition to code 0x3FF, but in some cases the last transition may be to a lower code. The
ideal transition to any code is:
Total unadjusted error (E
and the ideal straight-line transfer function. An alternate definition (with the same result) is the
difference between the actual transfer function and the ideal straight-line transfer function. This
measure of error includes inherent quantization error and all forms of circuit error (INL, DNL,
zero-scale, and full-scale) except input leakage error, which is not due to the ATD.
Input leakage error (E
the ideal transition to that code that is the result of input leakage across the real portion of the
impedance of the network that drives the analog input. This error is a system-observable error
which is not inherent to the ATD, so it is not added to total error. This error is:
Sampling error (E
Noise error (E
(noise source capacitively coupled directly on the signal) or power supply (V
and V
internal sources can be reduced (and specified operation achieved) by operating the ATD
conversion in wait mode and ceasing all IO activity. Reducing the error due to external sources is
dependent on system activity and board layout.
SS
) noise interfering with the ATD’s ability to resolve the input accurately. The error due to
N
Ideal Transition V =
) — The error due to noise on V
FS
S
) — The error due to inadequate time to charge the ATD circuitry
) — This is the difference between the transition voltage to the last valid code
IL
) — This is the error between the transition voltage to the current code and
TU
E
IL
) — This is the difference between the transition voltage to a given code
MC9S08GB60A Data Sheet, Rev. 1.02
(in V) = input leakage * R
(Current Code - 1/2)
2
N
AIN
, V
AS
REFH
*(V
, or V
REFH
REFL
– V
due to either direct coupling
REFL
)
DDAD
Functional Description
, V
SSAD
Eqn. 14-8
Eqn. 14-9
, V
DD
229
,