Rainbow Electronics MAX1068 User 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

or AGND, allow the input to swing from

(AGND - 0.3V) to (AV

+ 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

______________________________________________________________________________________

REFERENCE

REF

REFCAP

AGND

DGND

AIN0

AIN1

AIN2

AIN3

SCLK

DIN

ANALOG-INPUT

MULTIPLEXER

CONTROL

ACCUMULATOR

MEMORY

INPUT REGISTER

BIAS

OSCILLATOR

OUTPUT

DOUT

EOC

ANALOG-SWITCH FINE TIMING

SUCCESSIVE-APPROXIMATION

MAX1068

DAC

BUFFER

AIN4

AIN5

AIN6

AIN7

RAIL

COMPARATOR

DSPX

DSEL

DSPR

Figure 4. MAX1068 Functional Diagram