ST10F273Z4 STMicroelectronics, ST10F273Z4 Datasheet - Page 139

• Manufacturer Part Number: ST10F273Z4
• Description: 16-BIT MICROCONTROLLER WITH MAC UNIT, UP TO 832 KBYTES FLASH MEMORY AND UP TO 68 KBYTES RAM
• Manufacturer: STMicroelectronics

Specifications of ST10F273Z4

• Single Voltage Supply: 5 V ±10%

ST10F273Z4
24.7.4
Figure 37. A/D conversion characteristic
Analog reference pins
The accuracy of the A/D converter depends on how accurate is its analog reference: a noise
in the reference results in at least that much error in a conversion. A low pass filter on the
A/D converter reference source (supplied through pins V
in order to clean the signal, minimizing the noise. A simple capacitive bypassing may be
sufficient in most of the cases; in presence of high RF noise energy, inductors or ferrite
beads may be necessary.
In this architecture, V
circuitry of the A/D converter: there is an effective DC current requirement from the
reference voltage by the internal resistor string in the R-C DAC array and by the rest of the
analog circuitry.
An external resistance on V
reasons, series resistance are not advisable, and more in general any series devices in the
filter network should be designed to minimize the DC resistance.
Analog input pins
To improve the accuracy of the A/D converter, it is definitively necessary that analog input
pins have low AC impedance. Placing a capacitor with good high frequency characteristics
at the input pin of the device, can be effective: the capacitor should be as large as possible,
ideally infinite. This capacitor contributes to attenuating the noise present on the input pin;
besides, it sources charge during the sampling phase, when the analog signal source is a
high-impedance source.
Digital
out
(HEX)
Offset error OFS
3FD
3FC
3FE
3FB
3FA
3FF
007
006
005
004
003
002
001
000
1
2
AREF
3
Ideal characteristic
4
1 LSB (ideal)
and V
AREF
5
(7)
6
V
[LSB
AGND
(4)
could introduce error under certain conditions: for this
AIN
(3)
7
(2)
(5)
IDEAL
(LSB
pins represents also the power supply of the analog
IDEAL
= V
1018
AREF
)
(6)
/ 1024]
1020
(1)
(1) Example of an actual transfer curve
(2) The ideal transfer curve
(3) Differential Non-Linearity Error (DNL)
(4) Integral Non-Linearity Error (INL)
(5) Center of a step of the actual transfer curve
(6) Quantization Error (1/2 LSB)
(7) Total Unadjusted Error (TUE)
Offset error OFS
AREF
1022
and V
Electrical characteristics
1024
AGND
Bisector characteristic
Gain error GE
), is recommended
139/188