Stand-Alone, 10-Channel, 10-Bit System Monitors

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23

execute a manual conversion. See Figure 9 for manual

conversion timing:

1) Disable autoscan (set up register scan mode bit to

zero), if necessary.

2) Pull CS low.

3) Initiate a conversion by issuing a Manually

Triggered Conversion command (0000, followed by

the address bits of the channel to be converted).

4) Pull CS high to start the conversion.

5) Maintain a logic high on CS to allow for reference

power-up (if the reference mode requires it) and

conversion time.

6) Pull CS low.

7) Issue a Read Current Data Register for Selected-

Channel command (0010, followed by the same

address of the channel in the Manually Triggered

Conversion command).

Voltage Measurements

input channel) requires 10.6µs to complete. If the inter-

nal reference needs to power up (reference mode =

01), an additional 40µs is required every time the

MAX1153/MAX1154 come out of automatic shutdown

mode after a sample wait period greater than 80µs.

This internal acquisition channel samples and converts

with the following equation:

10.6µs (typ) per measurement.

Temperature Measurement

The MAX1153/MAX1154 perform temperature measure-

ment by measuring the voltage across a diode-con-

nected transistor at two different current levels. The

following equation illustrates the algorithm used for

temperature calculations:

temperature

V

V

x

HIGH

LOW

=−

⎡

⎣⎢

⎤

⎦⎥

()

q

k

nx ln

I

I

High

LOW

V

x current data register content x

V

DD

REF

=

⎛

⎝⎜

⎞

⎠⎟

2

1024

(_

_

_

)

C3

C2

C1 C0

A2

A1

A0

SCLK

DIN

DOUT

C3

C2

C1 C0

A2

A1

A0

A3

A3

CS

Figure 9. Manual Conversion Timing Without Reading Data