STM32F407IG datasheet(126/180 Pages) STMICROELECTRONICS

126 / 180 page

Electrical characteristics

STM32F405xx, STM32F407xx

126/180

Doc ID 022152 Rev 3

Equation 1: RAIN max formula

The formula above (Equation 1) is used to determine the maximum external impedance

allowed for an error below 1/4 of LSB. N = 12 (from 12-bit resolution) and k is the number of

sampling periods defined in the ADC_SMPR1 register.

Note:

ADC accuracy vs. negative injection current: injecting a negative current on any analog input

pins should be avoided as this significantly reduces the accuracy of the conversion being

performed on another analog input. It is recommended to add a Schottky diode (pin to

ground) to analog pins which may potentially inject negative currents.

Any positive injection current within the limits specified for IINJ(PIN) and ΣIINJ(PIN) in

Section 5.3.16 does not affect the ADC accuracy.

For external triggers, a delay of 1/fPCLK2 must be added to the latency specified in Table 67.

Table 68.

ADC accuracy at fADC = 30 MHz

(1)

Better performance could be achieved in restricted VDD, frequency and temperature ranges.

Symbol

Parameter

Test conditions

Typ

Max(2)

Based on characterization, not tested in production.

Unit

Total unadjusted error

fPCLK2 = 60 MHz,

fADC = 30 MHz, RAIN < 10 kΩ,

VDDA = 1.8

(3) to 3.6 V

If an inverted reset signal is applied to PDR_ON, this value can be lowered to 1.7 V when the device

operates in a reduced temperature range (0 to 70 °C).

±2

±5

LSB

Offset error

±1.5

±2.5

Gain error

±1.5

±3

Differential linearity error

±1

±2

Integral linearity error

±1.5

±3

AIN

k0.5

–

()

ADC

()

-------------------------------------------------------------- R

ADC

–

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