Rainbow Electronics MAX6692 - Manual (Page 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
CC and
clears the memory if V CC falls below 2.0V (typ). When
power is first applied and V CC rises above 2.0V (typ),
the logic blocks begin operating, although reads and
writes at V
CC
levels below 3V are not recommended. A
second V CC comparator, the ADC UVLO comparator
prevents the ADC from converting until there is suffi-
cient headroom (V
CC
= 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.
6 LHIGH 0
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.
5 LLOW 0
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.
4 RHIGH 0
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.
3 RLOW 0
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.
2 FAULT 0
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)