MAX6692MUA(2002) Просмотр технического описания (PDF) - Maxim Integrated

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MAX6692MUA
(Rev.:2002)

Precision SMBus-Compatible Remote/Local Temperature Sensors with Overtemperature Alarms

Maxim Integrated 

Precision SMBus-Compatible Remote/Local

Temperature Sensors with Overtemperature Alarms

Functional Diagram

VCC

MAX6648

MAX6692

DXP

DXN

ALERT

OVERT

MUX

REMOTE

LOCAL

DIODE

FAULT

S

Q

R

S

Q

R

2

ADC

CONTROL

LOGIC

8

8

REGISTER BANK

COMMAND BYTE

REMOTE TEMPERATURE

LOCAL TEMPERATURE

ALERT THRESHOLD

ALERT RESPONSE ADDRESS

OVERT THRESHOLD

SMBus

READ

WRITE

7

ADDRESS

DECODER

SMBDATA

SMBCLK

When measuring temperature with discrete remote sen-

sors, smaller packages, such as SOT23s, yield the best

thermal response times. Take care to account for ther-

mal gradients between the heat source and the sensor,

and ensure that stray air currents across the sensor

package do not interfere with measurement accuracy.

Self-heating does not significantly affect measurement

accuracy. Remote-sensor self-heating due to the diode

current source is negligible. For the local diode, the

worst-case error occurs when autoconverting at the

fastest rate and simultaneously sinking maximum current

at the ALERT output. For example, with VCC = 5.0V, at a

4Hz conversion rate and with ALERT sinking 1mA, the

typical power dissipation is:

5.0V x 500µA + 0.4V x 1mA = 2.9mW

øJ-A for the 8-pin µMAX package is about +221°C/W,

so assuming no copper PC board heat sinking, the

resulting temperature rise is:

∆T = 2.9mW x (+221°C/W) = +0.6409°C

Even under nearly worst-case conditions, it is difficult to

introduce a significant self-heating error.

14 ______________________________________________________________________________________

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