2.13.3 Analog-to-Digital Converter (ADC)

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Unless otherwise noted, ADC direct input performance is specified at 25 °C with nominal power supply voltages, with the output measured using the external voltage reference with the internal ADC in 12-bit mode and 500 KHz sampling frequency, after trimming and digital compensation.

Table 2-95. ADC Specifications
Specification	Test Conditions	Min.	Typ.	Max.	Units
Input voltage range (for driving ADC over its full range)		—	2.56	—	V
Gain error		—	±0.4	±0.7	%
Gain error	–55ºC to +125ºC	—	±0.4	±0.7	%
Input referred offset voltage		—	±1	±2	mV
Input referred offset voltage	–55ºC to +125ºC	—	±1	±4	mV
Integral non-linearity (INL)	RMS deviation from BFSL
	12-bit mode	—	1.71	—	LSB
	10-bit mode	—	0.60	1.00	LSB
	8-bit mode	—	0.2	0.33	LSB
Differential non-linearity (DNL)	12-bit mode	—	2.4	—	LSB
	10-bit mode	—	0.80	0.94	LSB
	8-bit mode	—	0.2	0.23	LSB
Signal to noise ratio		62	64	—	dB
Effective number of bits (ENOB) Figure 2-52. EQ 10	–1 dBFS input
	12-bit mode 10 KHz	9.9	10	—	Bits
	12-bit mode 100 KHz	9.9	10	—	Bits
	10-bit mode 10 KHz	9.5	9.6	—	Bits
	10-bit mode 100 KHz	9.5	9.6	—	Bits
	8-bit mode 10 KHz	7.8	7.9	—	Bits
	8-bit mode 100 KHz	7.8	7.9	—	Bits
Full power bandwidth	At –3 dB; –1 dBFS input	300	—	—	KHz
Analog settling time	To 0.1% of final value (with 1 KΩ source impedance and with ADC load)	—	2	—	µs
Input capacitance	Switched capacitance (ADC sample capacitor)	—	12	15	pF
	Cs: Static capacitance (Analog-to-Digital Converter (ADC))
	CM[n] input	—	5	7	pF
	TM[n] input	—	5	7	pF
	ADC[n] input	—	5	7	pF
Input resistance	Rin: Series resistance (Analog-to-Digital Converter (ADC))	—	2	—	KΩ
Input resistance	Rsh: Shunt resistance, exclusive of switched capacitance effects (Analog-to-Digital Converter (ADC))	10	—	—	MΩ
Input leakage current	–40 °C to +100 °C	—	1	—	µA
Power supply rejection ratio	DC	44	53	—	dB
ADC power supply operational current requirements	VCC33ADCx	—	—	2.5	mA
ADC power supply operational current requirements	VCC15A	—	—	2	mA

Note: All 3.3V supplies are tied together and varied from 3.0V to 3.6V. 1.5V supplies are held constant.

Table 2-96. VAREF Stabilization Time
VAREF Capacitor Value (µF)	Required Settling Time for 8-Bit and 10-Bit Mode (ms)	Required Settling Time for 12-Bit Mode (ms)
0.01	1	1
0.1	3	4
0.2	6	8
0.3	10	11
0.5	17	20
0.7	18	21
1	32	37
2.2	62	73
3.3	99	117
10	275	325
22	635	751
47	1318	1557