Rainbow Electronics MAX1189 - Manual (Page 12)

MAX1179/MAX1187/MAX1189
onto the analog lines. If the analog and digital sections
share the same supply, isolate the digital and analog
supply by connecting them with a low value (10
Ω)
resistor or ferrite bead.
The ADC is sensitive to high-frequency noise on the
AV
DD supply. Bypass AV DD to AGND with a 0.1µF
capacitor in parallel with a 1µF to 10µF low-ESR capaci-
tor with the smallest capacitor closest to the device.
Keep capacitor leads short to minimize stray inductance.
Definitions
Integral Nonlinearity
Integral nonlinearity (INL) is the deviation of the values
on an actual transfer function from a straight line. This
straight line can be either a best-straight-line fit or a line
drawn between the end points of the transfer function,
once offset and gain errors have been nullified. The
static linearity parameters for the MAX1179/MAX1187/
MAX1189 are measured using the endpoint method.
Differential Nonlinearity
Differential nonlinearity (DNL) is the difference between
an actual step-width and the ideal value of 1LSB. A
DNL error specification of 1LSB guarantees no missing
codes and a monotonic transfer function.
Signal-to-Noise Ratio
For a waveform perfectly reconstructed from digital
samples, signal-to-noise ratio (SNR) is the ratio of the
full-scale analog input (RMS value) to the RMS quanti-
zation error (residual error). The ideal, theoretical mini-
mum analog-to-digital noise is caused by quantization
noise error only and results directly from the ADC’s res-
olution (N bits):
SNR = ((6.02 ✕ N) + 1.76)dB
where N = 16 bits.
In reality, there are other noise sources besides quanti-
zation noise: thermal noise, reference noise, clock jitter,
16-Bit, 135ksps, Single-Supply ADCs with
Bipolar Analog Input Range
12 ______________________________________________________________________________________
Figure 12a. MAX1179 Analog Input Current
MAX1179
ANALOG INPUT CURRENT
vs. ANALOG INPUT VOLTAGE
ANALOG INPUT VOLTAGE (V)
ANALOG INPUT CURRENT (mA)
2.5 0 -2.5
-1.5
-1.0
-0.5
0
0.5
1.0
1.5
2.0
-2.0
-5.0 5.0
SHUTDOWN MODE
STANDBY MODE
Figure 12b. MAX1189 Analog Input Current
MAX1189
ANALOG INPUT CURRENT
vs. ANALOG INPUT VOLTAGE
ANALOG INPUT VOLTAGE (V)
ANALOG INPUT CURRENT (mA)
5 0 -5
-1.5
-1.0
-0.5
0
0.5
1.0
1.5
-10 10
SHUTDOWN MODE
STANDBY MODE
Figure 11. MAX1179/MAX1187/MAX1189 Fast-Settling Input
Buffer
MAX1179
MAX1187
MAX1189
MAX427
REF
**
*
AIN ANALOG
INPUT
*MAX1187 ONLY.
**MAX1179/MAX1189 ONLY.