Datasheet

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SLAS272F − JULY 2000 − REVISED JUNE 2004
37
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
electrical characteristics over recommended operating free-air temperature (unless otherwise
noted) (continued)
12-bit ADC, timing parameters
PARAMETER TEST CONDITIONS MIN NOM MAX UNIT
f
ADC12CLK
For specified performance of ADC12
linearity parameters
2.2V/
3V
0.45 5 6.3 MHz
f
ADC12OSC
Internal ADC12
oscillator
ADC12DIV=0,
f
ADC12CLK
=f
ADC12OSC
2.2 V/
3V
3.7 6.3 MHz
t
CONVERT
Conversion time
C
VREF+
≥ 5 µF, Internal oscillator,
f
ADC12OSC
= 3.7 MHz to 6.3 MHz
2.2 V/
3 V
2.06 3.51 µs
t
CONVERT
Conversion time
External f
ADC12CLK
from ACLK, MCLK or SMCLK:
ADC12SSEL ≠ 0
13×ADC12DIV×
1/f
ADC12CLK
µs
t
ADC12ON
‡
Turn on settling time of
the ADC
(see Note 1) 100 ns
t
Sample
‡
Sampling time
R
S
= 400 Ω, R
I
= 1000 Ω,
C
I
= 30 pF
3 V 1220
ns
t
Sample
‡
Sampling time
S I
C
I
= 30 pF
τ = [R
S
+ R
I
] x C
I;
(see Note 2)
2.2 V 1400
ns
†
Not production tested, limits characterized
‡
Not production tested, limits verified by design
NOTES: 1. The condition is that the error in a conversion started after t
ADC12ON
is less than ±0.5 LSB. The reference and input signal are already
settled.
2. Approximately ten Tau (τ) are needed to get an error of less than ±0.5 LSB:
t
Sample
= ln(2
n+1
) x (R
S
+ R
I
) x C
I
+ 800 ns where n = ADC resolution = 12, R
S
= external source resistance.
12-bit ADC, linearity parameters
PARAMETER TEST CONDITIONS MIN NOM MAX UNIT
E
I
Integral linearity error
1.4 V ≤ (V
eREF+
− V
REF−
/V
eREF−
) min ≤ 1.6 V
2.2 V/3 V
±2
LSB
E
I
Integral linearity erro
r
1.6 V < (V
eREF+
− V
REF−
/V
eREF−
) min ≤ [V
(AVCC)
]
2.2 V/3 V
±1.7
LSB
E
D
Differential linearity
error
(V
eREF+
− V
REF−
/V
eREF−
)
min
≤ (V
eREF+
− V
REF−
/V
eREF−
),
C
VREF+
= 10 µF (tantalum) and 100 nF (ceramic)
2.2 V/3 V ±1 LSB
E
O
Offset error
(V
eREF+
− V
REF−
/V
eREF−
)
min
≤ (V
eREF+
− V
REF−
/V
eREF−
),
Internal impedance of source R
S
< 100 Ω,
C
VREF+
= 10 µF (tantalum) and 100 nF (ceramic)
2.2 V/3 V ±2 ±4 LSB
E
G
Gain error
(V
eREF+
− V
REF−
/V
eREF−
)
min
≤ (V
eREF+
− V
REF−
/V
eREF−
),
C
VREF+
= 10 µF (tantalum) and 100 nF (ceramic)
2.2 V/3 V ±1.1 ±2 LSB
E
T
Total unadjusted
error
(V
eREF+
− V
REF−
/V
eREF−
)
min
≤ (V
eREF+
− V
REF−
/V
eREF−
),
C
VREF+
= 10 µF (tantalum) and 100 nF (ceramic)
2.2 V/3 V ±2 ±5 LSB