Peripheral operating requirements and behaviors
Table 23. 16-bit ADC operating conditions (continued)
Typ.1
Symbol Description
Conditions
Min.
Max.
Unit
Notes
Crate
ADC conversion 16 bit modes
rate
5
No ADC hardware
37.037
—
461.467
Ksps
averaging
Continuous
conversions enabled,
subsequent conversion
time
1. Typical values assume VDDA = 3.0 V, Temp = 25°C, fADCK = 1.0 MHz unless otherwise stated. Typical values are for
reference only and are not tested in production.
2. DC potential difference.
3. This resistance is external to MCU. The analog source resistance should be kept as low as possible in order to achieve the
best results. The results in this datasheet were derived from a system which has <8 Ω analog source resistance. The RAS
/
CAS time constant should be kept to <1ns.
4. To use the maximum ADC conversion clock frequency, the ADHSC bit should be set and the ADLPC bit should be clear.
5. For guidelines and examples of conversion rate calculation, download the ADC calculator tool: http://cache.freescale.com/
files/soft_dev_tools/software/app_software/converters/ADC_CALCULATOR_CNV.zip?fpsp=1
SIMPLIFIED
INPUT PIN EQUIVALENT
ZADIN
CIRCUIT
SIMPLIFIED
CHANNEL SELECT
CIRCUIT
Pad
leakage
due to
input
protection
ZAS
ADC SAR
ENGINE
RAS
RADIN
VADIN
CAS
VAS
RADIN
RADIN
RADIN
INPUT PIN
INPUT PIN
INPUT PIN
CADIN
Figure 10. ADC input impedance equivalency diagram
6.6.1.2 16-bit ADC electrical characteristics
Table 24. 16-bit ADC characteristics (VREFH = VDDA, VREFL = VSSA
)
Conditions1
Typ.2
Symbol Description
Min.
Max.
Unit
Notes
IDDA_ADC Supply current
0.215
—
1.7
mA
3
Table continues on the next page...
K20 Sub-Family Data Sheet, Rev. 4 5/2012.
Freescale Semiconductor, Inc.
37