Datasheet

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ADS8508
SLAS433 – SEPTEMBER 2005
ELECTRICAL CHARACTERISTICS (continued)
At T
A
= -40 °C to 85 °C, f
s
= 250 kHz, V
DIG
= V
ANA
= 5 V, using internal reference and fixed resistors (See Figure 28 and
Figure 29 ) (unless otherwise specified)
ADS8508IB
PARAMETER TEST CONDITIONS UNIT
MIN TYP MAX
±10 V range Int. Ref. with 0.1% external fixed -0.5 0.5
Full-scale
%FS
resistors
error
(4) (5)
All other ranges -0.5 0.5
Full-scale error drift Int. Ref. ±7 ppm/ °C
±10 V range Ext. Ref. with 0.1% external fixed -0.5 0.5
Full-scale
%FS
resistors
error
(4) (5)
All other ranges -0.5 0.5
Full-scale error drift Ext. Ref. ±2 ppm/ °C
Bipolar zero error
(4)
-1 1 mV
Bipolar zero error drift ±0.4 ppm/ °C
10 V range -5 5
Unipolar zero
mV
4 V and 5 V -3 3
error
(4)
range
Unipolar zero error drift ±2 ppm/ °C
Recovery to rated accuracy after 1- µF Capacitor to CAP 1 ms
power down
Power supply sensitivity -0.5 0.5
+4.75 V < V
D
< +5.25 V LSB
(V
DIG
= V
ANA
= V
D
)
AC ACCURACY
SFDR Spurious-free dynamic range f
I
= 45 kHz 86 95 dB
(6)
THD Total harmonic distortion f
I
= 45 kHz -95 -86 dB
SINAD f
I
= 45 kHz 72 73 dB
Signal-to-(noise+distortion)
–60-dB Input 32 dB
SNR Signal-to-noise ratio f
I
= 45 kHz 72 73 dB
Full-power bandwidth
(7)
500 kHz
SAMPLING DYNAMICS
Aperture delay 5 ns
Transient response FS Step 2 µs
Overvoltage recovery
(8)
150 ns
REFERENCE
Internal reference voltage No load 2.48 2.5 2.52 V
Internal reference source current 1
µA
(must use external buffer)
Internal reference drift 8 ppm/ °C
External reference voltage range for 2.3 2.5 2.7
V
specified linearity
External reference current drain Ext. 2.5-V Ref. 100 µA
DIGITAL INPUTS
Logic levels
V
IL
Low-level input voltage -0.3 0.8 V
V
IH
High-level input voltage 2.0 V
DIG
+0.3 V V
(4) As measured with circuit shown in Figure 28 and Figure 29 . Adjustable to zero with external potentiometer. Factory calibrated with 0.1%,
0.25-W resistors.
(5) For bipolar input ranges, full-scale error is the worst case of -full-scale or +full-scale uncalibrated deviation from ideal first and last code
transitions, divided by the transition voltage (not divided by the full-scale range) and includes the effect of offset error. For unipolar input
ranges, full-scale error is the deviation of the last code transition divided by the transition voltage. It also includes the effect of offset
error.
(6) All specifications in dB are referred to a full-scale ±10-V input.
(7) Full-power bandwidth is defined as the full-scale input frequency at which signal-to-(noise + distortion) degrades to 60 dB.
(8) Recovers to specified performance after 2 x FS input overvoltage.
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