MAX1462 Datasheet, PDF (15/16 Pages) Maxim Integrated Products – Low-Voltage, Low-Power, 16-Bit Smart ADC

Low-Voltage, Low-Power,
16-Bit Smart ADC
UNCOMPENSATED SENSOR ERROR
10
8
6
4
2
0
FSO
-2
-4
OFFSET
-6
-8
-10
0
10 20 30 40 50 60 70
TEMPERATURE (°C)
Figure 6. Sensor Characteristics Before Compensation
COMPENSATED TRANSDUCER ERROR
0.20
0.15
0.10
0.05
FSO
0
-0.05
OFFSET
-0.10
-0.15
-0.20
0
10 20 30 40 50 60 70
TEMPERATURE (°C)
Figure 7. Compensated Sensor/MAX1462 Pair
Figure 6 shows the characteristics of an individual
Lucas-NovaSensor model NPH8-100-EH, 0 to 15psig,
silicon pressure sensor.
Figure 7 shows the result of the compensated sen-
sor/MAX1462 pair.
Using the Compensated
Sensor/MAX1462 Pair
After calibration and removal from the test system, the
MAX1462 and the sensor form a mated pair. The START
pin can be connected to V_DD or left unconnected if the
sensor does not require a significant warmup time. Now
operation is simple: just apply power and latch the
parallel output D when EOC falls. Temperature is digi-
tized during the first half of t_ADC, so the MAX1462 pro-
vides a minimum sensor warmup time of 35ms. Using a
2MHz resonator, the conversion time (t_CONV) is nominally
67ms. If the Repeat Mode bit is set, conversions repeat at
a rate of 15Hz.
If the sensor requires more than 35ms of warmup time,
START may be used to initiate conversion (Figure 5). If
the Repeat Mode bit is set, START should remain high. If
the Repeat Mode bit is reset, START may be used to con-
trol externally the conversion rate of the MAX1462. After
the 12-bit parallel output D is latched, end the conversion
by taking START low for at least one clock cycle.
The output DAC converts the parallel digital output into
a serial bitstream on OUT. A simple external lowpass
filter, using the MAX1462 op amp, converts the OUT
bitstream into a ratiometric analog voltage (Figure 8).
The filter shown is an inverting configuration, but the
Gain and D_OFF coefficients of the characteristic equa-
tion can be adjusted to obtain either polarity. If the op
amp is not used, it can be powered down using the Op
Amp Power-Down bit in the configuration register.
The MAX1462 requires a minimum of external compo-
nents:
• One power-supply bypass capacitor (C1) from V_DD
to V_SS.
• One 2MHz ceramic resonator (X₁).
• Two 10kΩ resistors for the AGND pin.
• If an analog output is desired, two 500kΩ resistors
and a 1µF capacitor are needed for filtering.
MAX1462 Evaluation/
Development Kit
The MAX1462 evaluation kit (EV kit) speeds the devel-
opment of MAX1462-based transducer prototypes and
test systems. First-time users of the MAX1462 are
strongly encouraged to use this kit, which includes:
1) Evaluation board, with a MAX1462 sample and a sili-
con pressure sensor, ready for customer evaluation.
2) Interface board that must be connected to a PC par-
allel port.
3) MAX1462 communication/compensation software
(Windows compatible), which enables programming
of the MAX1462 one module at a time.
4) Detailed Design/Applications manual, developed for
sensor-test engineers.
The evaluation kit order number is MAX1462EVKIT.
Chip Information
TRANSISTOR COUNT: 59,855
SUBSTRATE CONNECTED TO V_SS
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