Rainbow-electronics MAX6692 Manual do Utilizador descarregar pdf (Página 11)

MAX6648/MAX6692

Precision SMBus-Compatible Remote/Local

Temperature Sensors with Overtemperature Alarms

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POR and UVLO

To prevent ambiguous power-supply conditions from

corrupting the data in memory and causing erratic

behavior, a POR voltage detector monitors V

and

clears the memory if V

falls below 2.0V (typ). When

power is first applied and V

rises above 2.0V (typ),

the logic blocks begin operating, although reads and

writes at V

levels below 3V are not recommended. A

second V

comparator, the ADC UVLO comparator

prevents the ADC from converting until there is suffi-

cient headroom (V

= 2.8V typ).

Power-Up Defaults

Power-up defaults include:

• Interrupt latch is cleared.

• ADC begins autoconverting at a 4Hz rate.

• Command byte is set to 00h to facilitate quick local

temperature receive byte queries.

• Local (internal) T

HIGH

limit set to +85°C.

• Local (internal) T

LOW

limit set to 0°C.

• Remote (external) T

HIGH

limit set to +85°C.

• Remote (external) T

LOW

limit set to 0°C.

• OVERT internal limit is set to +85°C; every external

limit is set to +110°C (MAX6648).

• OVERT limits are set to +85°C (MAX6692).

Applications Information

Remote-Diode Selection

The MAX6648/MAX6692 can directly measure the die

temperature of CPUs and other ICs that have on-board

temperature-sensing diodes (see Typical Operating

Circuit), or they can measure the temperature of a dis-

crete diode-connected transistor.

BIT

NAME

POR

STATE

FUNCTION

7 (MSB) BUSY

0 A/D is busy converting when 1.

LHIGH

Local (internal) high-temperature alarm has tripped when 1; cleared by POR or readout of the

status byte if the fault condition no longer exists.

LLOW

Local (internal) low-temperature alarm has tripped when 1; cleared by POR or readout of the

status byte if the fault condition no longer exists.

RHIGH

Remote (external) high-temperature alarm has tripped when 1; cleared by POR or readout of the

status byte if the fault condition no longer exists.

RLOW

Remote (external) low-temperature alarm has tripped when 1; cleared by POR or readout of the

status byte if the fault condition no longer exists.

FAULT

A 1 indicates DXN and DXP are either shorted or open; cleared by POR or readout of the status

byte if the fault condition no longer exists.

1 EOT 0

A 1 indicates the remote (external) junction temperature exceeds the external OVERT threshold.

0 IOT 0 A 1 indicates the local (internal) junction temperature exceeds the internal OVERT threshold.

Table 7. Status Register Bit Assignments (02h)

DATA

CONVERSION

RATE (Hz)

00h 0.0625

01h 0.125

02h 0.25

03h 0.5

04h 1

05h 2

06h 4

07h 4

08h-FFh Reserved

Table 8. Conversion-Rate Control Byte

(04h)

1 2 ... 6 7 8 9 10 11 12 13 14 15 16 17

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