Datasheet
ADS7279
ADS7280
SBAS436A – MAY 2008 – REVISED JUNE 2009 ...............................................................................................................................................................
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ELECTRICAL CHARACTERISTICS (continued)
At T
A
= – 40 ° C to +85 ° C, +VA = 2.7V to 3.6V, +VBD = 1.65V to 1.5x(+VA), V
REF
= 2.5V, f
SAMPLE
= 1MHz for 3V ≤ +VA ≤ 3.6V,
and f
SAMPLE
= 900kHz for 3V < +VA ≤ 2.7V using external clock, unless otherwise noted.
ADS7279, ADS7280
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
DYNAMIC CHARACTERISTICS
V
IN
= 2.5V
PP
at 10kHz – 100.8
THD Total harmonic distortion
(4)
dB
V
IN
= 2.5V
PP
at 100kHz – 88.4
V
IN
= 2.5V
PP
at 10kHz 81 83.1
SNR Signal-to-noise ratio dB
V
IN
= 2.5V
PP
at 100kHz 82
V
IN
= 2.5V
PP
at 10kHz 83
SINAD Signal-to-noise + distortion dB
V
IN
= 2.5V
PP
at 100kHz 81.4
V
IN
= 2.5V
PP
at 10kHz 102.6
SFDR Spurious-free dynamic range dB
V
IN
= 2.5V
PP
at 100kHz 89.8
– 3dB small-signal bandwidth 30 MHz
CLOCK
Internal conversion clock frequency 21 22 23.5 MHz
Used as I/O clock only 42
SCLK external serial clock MHz
As I/O clock and conversion clock 1 42
EXTERNAL VOLTAGE REFERENCE INPUT
f
SAMPLE
≤ 500kSPS, 2.7V ≤ +VA < 3V 0.3 2.525
f
SAMPLE
≤ 500kSPS, 3V ≤ +VA < 3.6V 0.3 3
Input
V
REF
[REF+ – (REF – )]
V
REF
reference f
SAMPLE
> 500kSPS, 2.7V ≤ +VA < 3V 2.475 2.525 V
range
f
SAMPLE
> 500kSPS, 3V ≤ +VA < 3.6V 2.475 3
(REF – ) – AGND – 0.1 0.1
Resistance
(5)
Reference input 40 k Ω
DIGITAL INPUT/OUTPUT
Logic family — CMOS
V
IH
High-level input voltage (+VA × 1.5)V ≥ +VBD ≥ 1.65V 0.65 × (+VBD) +VBD + 0.3 V
V
IL
Low-level input voltage (+VA × 1.5)V ≥ +VBD ≥ 1.65V – 0.3 0.35 × (+VBD) V
I
I
Input current V
I
= +VBD or BDGND – 50 50 nA
C
I
Input capacitance 5 pF
(+VA × 1.5)V ≥ +VBD ≥ 1.65V,
V
OH
High-level output voltage +VBD – 0.6 +VBD V
I
O
= 100 µ A
(+VA × 1.5)V ≥ +VBD ≥ 1.65V,
V
OL
Low-level output voltage 0 0.4 V
I
O
= 100 µ A
C
O
Output capacitance 5 pF
C
L
Load capacitance 30 pF
Data format — straight binary
(4) Calculated on the first nine harmonics of the input frequency.
(5) Can vary ± 30%.
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