Texas Instruments SM320F2812-HT specifications DC Specifications1

SM320F2812-HT

www.ti.com SGUS062A –JUNE 2009 –REVISED APRIL 2010

6.29.2ADC Electrical Characteristics Over Recommended Operating Conditions

Table 6-46. DC Specifications(1) (2)

	PARAMETER		TA = –55°C to 220°C			UNIT
			MIN	TYP	MAX
Resolution			12			Bits
ADC clock(3)			1			kHz
					25	MHz
		ACCURACY
INL (Integral nonlinearity)(4)		1–18.75 MHz ADC clock			±1.5	LSB
DNL (Differential nonlinearity)(4)		1–18.75 MHz ADC clock			±1	LSB
Offset error(5)			–80		80	LSB
Overall gain error with internal			–200		200	LSB
reference(6)
Overall gain error with external		If ADCREFP-ADCREFM = 1 V ±0.1%	–50		50	LSB
reference(7)
Channel-to-channel offset variation				±8		LSB
Channel-to-channel Gain variation				±8		LSB
		ANALOG INPUT
Analog input voltage (ADCINx to			0		3	V
ADCLO)(8)
ADCLO			–5	0	5	mV
Input capacitance				10		pF
Input leakage current				3	±5	μA
		INTERNAL VOLTAGE REFERENCE(6)
Accuracy, ADCVREFP			1.9	2	2.1	V
Accuracy, ADCVREFM			0.95	1	1.05	V
Voltage difference, ADCREFP –				1		V
ADCREFM
Temperature coefficient				50		PPM/°C
Reference noise				100		V
		EXTERNAL VOLTAGE REFERENCE(7)
Accuracy, ADCVREFP			1.9	2	2.1	V
Accuracy, ADCVREFM			0.95	1	1.05	V
Input voltage difference, ADCREFP –			0.99	1	1.01	V
ADCREFM

(1)Not production tested.

(2)Tested at 12.5-MHz ADCCLK

(3)If SYSCLKOUT ≤ 25 MHz, ADC clock ≤ SYSCLKOUT/2

(4)The INL degrades for frequencies beyond 18.75 MHz –25 MHz. Applications that require these sampling rates should use a 20-kΩresistor as bias resistor on the ADCRESEXT pin. This improves overall linearity and typical current drawn by the ADC is a few mA more than 24.9 kW bias.

(5)1 LSB has the weighted value of 3.0/4096 = 0.732 mV.

(6)A single internal band gap reference (±5% accuracy) sources both ADCREFP and ADCREFM signals, and hence, these voltages track together. The ADC converter uses the difference between these two as its reference. The total gain error is the combination of the gain error shown here and the voltage reference accuracy (ADCREFP – ADCREFM). A software-based calibration procedure is recommended for better accuracy. See F2812 ADC Calibration Application Note (literature number SPRA989) and Section 5.2, Documentation Support, for relevant documents.

(7)In this mode, the accuracy of external reference is critical for overall gain. The voltage difference (ADCREFP–ADCREFM) determines the overall accuracy.

(8)Voltages above VDDA + 0.3 V or below VSS – 0.3 V applied to an analog input pin may temporarily affect the conversion of another pin. To avoid this, the analog inputs should be kept within these limits.

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