Rainbow Electronics MAX1068 - Manual (Page 13)

that includes a longer acquisition time (11.5 clock
cycles). Longer acquisition times are useful in applica-
tions with input source resistances greater than 1k
Ω.
Noise increases when using large source resistances. To
improve the input signal bandwidth under AC conditions,
drive AIN_ with a wideband buffer (>10MHz) that can
drive the ADC’s input capacitance and settle quickly.
Input Bandwidth
The ADC’s input-tracking circuitry has a 4MHz small-
signal bandwidth, making possible the digitization of
high-speed transient events and the measurement of
periodic signals with bandwidths exceeding the ADC’s
sampling rate by using undersampling techniques. To
avoid aliasing of unwanted, high-frequency signals into
the frequency band of interest, use anti-alias filtering.
Analog Input Protection
Internal protection diodes, which clamp the analog
input to AV
DD or AGND, allow the input to swing from
(AGND - 0.3V) to (AV DD + 0.3V) without damaging the
device. If the analog input exceeds 300mV beyond the
supplies, limit the input current to 10mA.
MAX1067/MAX1068
Multichannel, 14-Bit, 200ksps Analog-to-Digital
Converters
______________________________________________________________________________________ 13
REFERENCE
REF
REFCAP AV DD DV DD
AGND
AGND DGND
AIN0
AIN1
AIN2
AIN3
SCLK
CS
DIN
ANALOG-INPUT
MULTIPLEXER
MULTIPLEXER
CONTROL
ACCUMULATOR
MEMORY
INPUT REGISTER
BIAS
OSCILLATOR
OUTPUT DOUT
EOC
ANALOG-SWITCH FINE TIMING
SUCCESSIVE-APPROXIMATION
REGISTER
MAX1068
DAC
BUFFER
AIN4
AIN5
AIN6
AIN7
AZ
RAIL
COMPARATOR
DSPX DSEL
DSPR
Figure 4. MAX1068 Functional Diagram