ATSAM4LS4BA-AU View Datasheet(PDF) - Atmel Corporation

Part Name

Description

Manufacturer

ATSAM4LS4BA-AU

ATSAM ARM-based Flash MCU

Atmel Corporation 

ATSAM4L8/L4/L2

Table 9-48. Unipolar mode, gain=1

PSRR(1)

DC supply current(1)

fVdd=100kHz, VDDIO=3.6V

fVdd=1MHz, VDDIO=3.6V

VDDANA=3.6V

VDDANA=1.6V,

ADVREFP=1.0V

62

dB

49

1

2

mA

1

1.3

1.

These values are based on simulation. These values are not covered by test limits in production or characterization.

2.

These values are based on characterization and not tested in production, and valid for an input voltage between 10% to 90% of

reference voltage.

9.9.4.1

Inputs and Sample and Hold Acquisition Times

The analog voltage source must be able to charge the sample and hold (S/H) capacitor in the

ADC in order to achieve maximum accuracy. Seen externally the ADC input consists of a resis-

tor ( RSAMPLE ) and a capacitor ( CSAMPLE ). In addition, the source resistance ( RSOURCE ) must be

taken into account when calculating the required sample and hold time. Figure 9-6 shows the

ADC input channel equivalent circuit.

Figure 9-6. ADC Input

VDDANA/2

RSOURCE

Analog Input

ADx

RSAMPLE

CSAMPLE

VIN

To achieve n bits of accuracy, the CSAMPLE capacitor must be charged at least to a voltage of

VCSAMPLE ≥ VIN × (1 – 2–(n + 1))

The minimum sampling time tSAMPLEHOLD for a given RSOURCE can be found using this formula:

tSAMPLEHOLD ≥ (RSAMPLE + RSOURCE) × (CSAMPLE) × (n + 1) × ln(2)

for a 12 bits accuracy :

tSAMPLEHOLD ≥ (RSAMPLE + RSOURCE) × (CSAMPLE) × 9, 02

where

tSAMPLEHOLD = 2-----×-----f-1-A----D-----C--

42023GS–SAM–03/2014

136

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