MAX1460 Просмотр технического описания (PDF) - Maxim Integrated

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MAX1460

Low-Power, 16-Bit Smart ADC

Maxim Integrated 

MAX1460

Low-Power, 16-Bit Smart ADC

This algorithm minimizes the error directly at the six

test conditions, AS, AL, BS, BL, CS, and CL. Space the

temperatures A, B, and C widely to minimize the signalto-

noise ratio of the measurement. If there is a large error

remaining in the finished product, move the calibration

temperatures closer to the peak error temperatures.

Similarly, full-scale sensor excitation may not be the best

calibration condition if the sensor has nonlinearities. Move

S and L away from full scale.

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 com-

pensated sensor/MAX1460 pair.

Using the Compensated

Sensor/MAX1460 Pair

After calibration and removal from the test system, the

MAX1460 and the sensor form a mated pair. The START

pin can be connected to VDD or left unconnected if the

sensor does not require a significant warm-up time. Now

operation is simple: just apply power and latch the parallel

output D when EOC falls. Temperature is digitized during

the first half of tADC, so the MAX1460 provides a minimum

sensor warm-up time of 35ms. Using a 2MHz resonator,

the conversion time tCONV 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 warm-up time,

the START pin 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 externally control the conversion rate of the MAX1460.

After the 12-bit parallel output D is latched, end the con-

version 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 MAX1460 op amp, converts the OUT bit-

stream into a ratiometric analog voltage (Figure 8). The

filter shown is an inverting configuration, but the Gain

and DOFF coefficients of the characteristic equation 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 MAX1460 requires a minimum of external components:

●● One power-supply bypass capacitor (C1) from VDD

to VSS.

●● 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.

MAX1460 Evaluation/

Development Kit

The MAX1460 evaluation kit (EV kit) speeds the develop-

ment of MAX1460-based transducer prototypes and test

systems. First-time users of the MAX1460 are strongly

encouraged to use this kit, which includes:

1) Evaluation board, with a MAX1460 sample and a sili-

con pressure sensor, ready for customer evaluation.

2) Interface board that must be connected to a PC paral-

lel port.

3) MAX1460 communication/compensation software

(Windows compatible), which enables programming of

the MAX1460 one module at a time.

4) Detailed Design/Applications manual, developed for

sensor-test engineers.

The evaluation kit order number is MAX1460EVKIT.

Pin Configuration

N.C. 1

N.C. 2

AGND 3

START 4

I.C. 5

D6 6

D7 7

D8 8

D9 9

D10 10

D11 11

N.C. 12

MAX1460

36 N.C.

35 AMP-

34 AMP+

33 AMPOUT

32 N.C.

31 N.C.

30 OUT

29 D5

28 D4

27 D3

26 D2

25 D1

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