Datasheet

www.ti.com
SPECIFICATIONS
ADS8405
SLAS427 – DECEMBER 2004
T
A
= –40 ° C to 85 ° C, +VA = 5 V, +VBD = 3 V or 5 V, V
ref
= 4.096 V, f
SAMPLE
= 1.25 MHz (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
ANALOG INPUT
Full-scale input voltage
(1)
+IN – (–IN) 0 V
ref
V
+IN –0.2 V
ref
+ 0.2
Absolute input voltage V
–IN –0.2 0.2
Input capacitance 25 pF
Input leakage current 0.5 nA
SYSTEM PERFORMANCE
Resolution 16 Bits
ADS8405I 15
No missing codes Bits
ADS8405IB 16
ADS8405I –4 ± 2 4
INL Integral linearity
(2) (3)
LSB
ADS8405IB –2 ± 1 2
ADS8405I –2 ± 1 2
DNL Differential linearity LSB
ADS8405IB –1 ± 0.75 1.5
ADS8405I –3 ± 1 3 mV
E
O
Offset error
(4)
ADS8405IB –1.5 ± 0.5 1.5 mV
ADS8405I –0.15 0.15
E
G
Gain error
(4) (5)
%FS
ADS8405IB –0.098 0.98
Noise 60 µV RMS
At FFFFh output code, +VA = 4.75 V
DC Power supply rejection ratio 2 LSB
to 5.25 V, V
ref
= 4.096 V
(4)
SAMPLING DYNAMICS
Conversion time 500 650 ns
Acquisition time 150 ns
Throughput rate 1.25 MHz
Aperture delay 2 ns
Aperture jitter 25 ps
Step response 100 ns
Overvoltage recovery 100 ns
DYNAMIC CHARACTERISTICS
VIN = 4 V
p-p
at 100 kHz –90 dB
THD Total harmonic distortion
(6)
VIN = 4 V
p-p
at 500 kHz –88.5 dB
SNR Signal-to-noise ratio VIN = 4 V
p-p
at 100 kHz 86 dB
SINAD Signal-to-noise + distortion VIN = 4 V
p-p
at 100 kHz 85 dB
VIN = 4 V
p-p
at 100 kHz 90 dB
SFDR Spurious free dynamic range
VIN = 4 V
p-p
at 500 kHz 88 dB
-3dB Small signal bandwidth 5 MHz
EXTERNAL VOLTAGE REFERENCE INPUT
Reference voltage at REFIN, V
ref
2.5 4.096 4.2 V
Reference resistance
(7)
500 k Ω
(1) Ideal input span, does not include gain or offset error.
(2) LSB means least significant bit
(3) This is endpoint INL, not best fit.
(4) Measured relative to an ideal full-scale input (+IN – (–IN)) of 4.096 V.
(5) This specification does not include the internal reference voltage error and drift.
(6) Calculated on the first nine harmonics of the input frequency.
(7) Can vary ± 20%
3