MAX1333 Maxim Integrated Products, MAX1333 Datasheet - Page 14

• Manufacturer Part Number: MAX1333
• Description: (MAX1332 / MAX1333) True-Differential 12-Bit ADCs
• Manufacturer: Maxim Integrated Products

of interest, lowpass or bandpass filtering is recom-
mended to limit the bandwidth of the input signal.
To improve the input signal bandwidth under AC condi-
tions, drive the input with a wideband buffer (>50MHz)
that can drive the ADC’s input capacitance (14pF) and
settle quickly. Most applications require an input buffer
to achieve 12-bit accuracy. Although slew rate and
bandwidth are important, the most critical input buffer
specification is settling time. The sampling requires an
acquisition time of 52µs for the MAX1332 and 78µs for
the MAX1333. At the beginning of the acquisition, the
ADC internal sampling capacitors connect to the ana-
log inputs, causing some disturbance. Ensure the
amplifier is capable of settling to at least 12-bit accura-
cy during this interval. Use a low-noise, low-distortion,
3Msps/2Msps, 5V/3V, 2-Channel, True-
Differential 12-Bit ADCs
Figure 3a. Equivalent Input Circuit (Acquisition Mode)
Figure 3b. Equivalent Input Circuit (Hold/Conversion Mode)
14
______________________________________________________________________________________
AIN_N
AIN_P
AIN_N
AIN_P
AV
AV
DD
DD
AGND
AGND
Input Buffer
C
C
C
C
IN+
IN-
IN+
IN-
R
R
R
R
IN+
IN-
IN+
IN-
wideband amplifier that settles quickly and is stable
with the ADC’s 14pF input capacitance.
See the Maxim website (www.maxim-ic.com) for appli-
cation notes on how to choose the optimum buffer
amplifier for an ADC application. The MAX4430 is one
of the devices that is ideal for this application.
The MAX1332/MAX1333 produce a digital output that
corresponds to the differential analog input voltage as
long as the differential analog inputs are within the
specified range. When operating in unipolar mode
(BIP/UNI = 0), the usable differential analog input range
is from 0 to V
(BIP/UNI = 1), the differential analog input range is from
-V
REF
/2 to +V
Differential Analog Input Range and
COMP
COMP
REF
REF
. When operating in bipolar mode
/2. In both unipolar and bipolar
CAPACITIVE
CAPACITIVE
CONTROL
CONTROL
DAC
LOGIC
LOGIC
DAC
Protection