ST72324BLJ2B5 View Datasheet(PDF) - STMicroelectronics
Part Name
Description
Manufacturer
ST72324BLJ2B5
STMicroelectronics
ST72324BLJ2B5 Datasheet PDF : 154 Pages
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ST72324Lxx
12.12 10-BIT ADC CHARACTERISTICS
Subject to general operating conditions for VDD, fCPU, and TA unless otherwise specified.
Symbol
Parameter
Conditions
Min
Typ
Max
fADC
VAREF
VAIN
ADC clock frequency
Analog reference voltage 1)
Conversion voltage range 2)
0.4
VDD
VSSA
Positive input leakage current for analog
input
-40°C≤TA≤85°C range
Ilkg
ROM devices: negative input leakage
current on analog pins 5)
VIN<VSS, | IIN |< 400µA
on adjacent analog pin
5
1
VDD
VAREF
1
6
RAIN
CAIN
fAIN
External input impedance
External capacitor on analog input
Variation freq. of analog input signal
see
Figure 78
and
Figure
792)3)4)
CADC Internal sample and hold capacitor
12
tADC
Conversion time (Sample+Hold)
fCPU=4MHz, SPEED=0 fADC=1MHz
15
tADC
- No of sample capacitor loading cycles
- No. of Hold conversion cycles
4
11
Unit
MHz
V
µA
µA
kΩ
pF
Hz
pF
µs
1/fADC
Figure 78. RAIN max. vs fADC with CAIN=0pF3)
Figure
79.
Recommended
CAIN
&
RAIN
4)
values.
1000
45
Cain 10 nF
40
35
100
Cain 22 nF
30
1 MHz
Cain 47 nF
25
10
20
15
10
1
5
0
0
10
30
70
CPARASITIC (pF)
0.1
0.01
0.1
1
10
fAIN(KHz)
Notes:
1. When VAREF and VSSA pins are not available on the pinout, the ADC refers to VDD and VSS.
2. Any added external serial resistor will downgrade the ADC accuracy (especially for resistance greater than 10kΩ). Data
based on characterization results, not tested in production.
3. CPARASITIC represents the capacitance of the PCB (dependent on soldering and PCB layout quality) plus the pad ca-
pacitance (3pF). A high CPARASITIC value will downgrade conversion accuracy. To remedy this, fADC should be reduced.
4. This graph shows that depending on the input signal variation (fAIN), CAIN can be increased for stabilization time and
decreased to allow the use of a larger serial resistor (RAIN).
5.The analog inputs of ROM devices are designed to be negative current tolerant. On Flash devices, injecting negative
current on any of the analog input pins significantly reduces the accuracy of any conversion being performed on any an-
alog input.
Analog pins can be protected against negative injection by adding a Schottky diode (pin to ground). Injecting negative
current on digital input pins degrades ADC accuracy especially if performed on a pin close to the analog input pins.
Any positive injection current within the limits specified for IINJ(PIN) and ΣIINJ(PIN) in Section 12.8 does not affect the ADC
accuracy.
132/154
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