MAX1195ECM+TD Maxim Integrated Products, MAX1195ECM+TD Datasheet - Page 17

• Manufacturer Part Number: MAX1195ECM+TD
• Description: IC ADC 8BIT 40MSPS DL 48-TQFP
• Manufacturer: Maxim Integrated Products

Specifications of MAX1195ECM+TD

• Number Of Bits: 8
• Sampling Rate (per Second): 40M
• Data Interface: Parallel
• Number Of Converters: 2
• Power Dissipation (max): 108mW
• Voltage Supply Source: Single Supply
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 48-TQFP Exposed Pad, 48-eTQFP, 48-HTQFP, 48-VQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Figure 8. External Buffered (MAX4250) Reference Drive Using a MAX6062 Bandgap Reference
passive 10Hz filter following the buffer attenuates noise
produced in the voltage reference and buffer stages.
This filtered noise density, which decreases for higher
frequencies, meets the noise levels specified for preci-
sion ADC operation.
Connecting each REFIN to analog ground disables the
internal reference of each device, allowing the internal
reference ladders to be driven directly by a set of
external reference sources. Followed by a 10Hz low-
pass filter and precision voltage divider, the MAX6066
generates a DC level of 2.500V. The buffered outputs
of this divider are set to 2.0V, 1.5V, and 1.0V, with an
accuracy that depends on the tolerance of the divider
resistors. The three voltages are buffered by the
MAX4252, which provides low noise and low DC offset.
The individual voltage followers are connected to 10Hz
lowpass filters, which filter both the reference voltage
and amplifier noise to a level of 3nV/√Hz. The 2.0V and
Unbuffered External Reference Drives
Dual, 8-Bit, 40Msps, 3V, Low-Power ADC with
NOTE: ONE FRONT-END REFERENCE CIRCUIT DESIGN MAY BE USED WITH UP TO 1000 ADCs.
3.3V
MAX6062
1
3
______________________________________________________________________________________
Internal Reference and Parallel Outputs
2
10Hz LOWPASS
FILTER
0.1µF
16.2kΩ
1µF
0.1µF
3
4
Multiple ADCs
MAX4250
5
2
3.3V
1
10Hz LOWPASS
FILTER
162Ω
100µF
1.0V reference voltages set the differential full-scale
range of the associated ADCs at 2V
1.0V buffers drive the ADC’s internal ladder resistances
between them.
Note that the common power supply for all active com-
ponents removes any concern regarding power-supply
sequencing when powering up or down. With the out-
puts of the MAX4252 matching better than 0.1%, the
buffers and subsequent lowpass filters can be replicat-
ed to support as many as 32 ADCs. For applications
that require more than 32 matched ADCs, a voltage
reference and divider string common to all converters
is highly recommended.
A frequently used modulation technique in digital com-
munications applications is quadrature amplitude
modulation (QAM). Typically found in spread-spec-
trum-based systems, a QAM signal represents a carrier
frequency modulated in both amplitude and phase. At
the transmitter, modulating the baseband signal with
0.1µF
0.1µF
2.048V
Typical QAM Demodulation Application
0.1µF
0.1µF
N.C.
N.C.
0.1µF
0.1µF
0.1µF
0.1µF
29
31
32
29
31
32
1
2
1
2
REFOUT
REFIN
REFP
REFN
COM
REFOUT
REFIN
REFP
REFN
COM
MAX1195
MAX1195
N = 1000
N = 1
0.1µF
P-P
. The 2.0V and
2.2µF
10V
17