ST72561AR7-Auto datasheet(299/324 Pages) STMICROELECTRONICS

299 / 324 page

ST72561-Auto

Electrical characteristics

Doc ID 12370 Rev 8

299/324

Figure 143. Recommended CAIN/RAIN values

Figure 143 shows that depending on the input signal variation (fAIN), CAIN can be increased for stabilization

time and reduced to allow the use of a larger serial resistor (RAIN). It is valid for all fADC frequencies ≤

4MHz.

Figure 144. Typical application with ADC

Analog power supply and reference pins

Depending on the MCU pin count, the package may feature separate VDDA and VSSA analog

power supply pins. These pins supply power to the A/D converter cell and function as the

high and low reference voltages for the conversion. In smaller packages VDDA and VSSA pins

are not available and the analog supply and reference pads are internally bonded to the VDD

and VSS pins.

Separation of the digital and analog power pins allow board designers to improve A/D

performance. Conversion accuracy can be impacted by voltage drops and noise in the event

of heavily loaded or badly decoupled power supply lines (see General PCB design

guidelines).

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.

●

Use separate digital and analog planes. The analog ground plane should be connected

to the digital ground plane via a single point on the PCB.

●

Filter power to the analog power planes. It is recommended to connect capacitors, with

good high frequency characteristics, between the power and ground lines, placing

0.1

100

1000

0.01

0.1

fAIN(KHz)

Cain 10 nF

Cain 22 nF

Cain 47 nF

AINx

ST72XXX

VDD

±1µA

0.6V

CADC

6pF

VAIN

RAIN

10-Bit A/D

Conversion

Ω(max)

CAIN

ST72561AR7-Auto Datasheet(PDF) 299 Page - STMicroelectronics

ST72561AR7-Auto Datasheet(HTML) 299 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL