
ST7LITE0, ST7SUPERLITE
103/122
ADC CHARACTERISTICS
(Cont’d)
13.11.0.1 General PCB Design Guidelines
To obtain best results, some general design and
layout rules should be followed when designing
the application PCB to shield the noise-sensitive,
analog physical interface from noise-generating
CMOS logic signals.
– Properly place components and route the signal
traces on the PCB to shield the analog inputs.
Analog signals paths should run over the analog
ground plane and be as short as possible. Isolate
analog signals from digital signals that may
switch while the analog inputs are being sampled
by the A/D converter. Do not toggle digital out-
puts on the same I/O port as the A/D input being
converted.
ADC Accuracy
T
A
= -40°C to 85°C, unless otherwise specified
Notes:
1)
Data based on characterization results over the whole temperature range, monitored in production.
2)
Injecting negative current on any of the analog input pins significantly reduces the accuracy of any conversion being
performed on any analog 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 I
INJ(PIN)
and
Σ
I
INJ(PIN)
in
Section 13.8
does not affect the ADC
accuracy.
Symbol
E
T
E
O
E
G
E
D
E
L
E
T
E
O
E
G
E
D
E
L
Parameter
Conditions
Typ
±1
Max
Unit
Total unadjusted error
2)
Offset error
2)
Gain Error
2)
Differential linearity error
2)
Integral linearity error
2)
Total unadjusted error
2)
Offset error
2)
Gain Error
2)
Differential linearity error
2)
Integral linearity error
2)
f
CPU
=4MHz, f
ADC
=2MHz ,V
DD
=5.0V
LSB
-0.5 / +1
±1
±1
1)
±1
1)
f
CPU
=8MHz, f
ADC
=4MHz ,V
DD
=5.0V
±2
LSB
-0.5 / 3.5
-2 / 0
±1
1)
±1
1)