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AD 746±
GENERAL DESCRIPTION
FEATURES
The ADT74611 is a dual-channel digital thermometer and
under/over temperature alarm, intended for use in PCs and
thermal management systems. It is pin- and register-compatible
with the ADM1032. The ADT7461 has three additional features:
series resistance cancellation (where up to 3 kΩ (typical) of
resistance in series with the temperature monitoring diode may
be automatically cancelled from the temperature result, allowing
On-chip and remote temperature sensor
0.25°C resolution/1°C accuracy on remote channel
1°C resolution/3°C accuracy on local channel
Automatically cancels up to 3 kΩ (typ) of resistance in series
with remote diode to allow noise filtering
Extended, switchable temperature measurement range 0°C
to +127°C (default) or –55°C to +150°C
Pin- and register-compatible with ADM1032
2-wire SMBus serial interface with SMBus alert support
Programmable over/under temperature limits
Offset registers for system calibration
ALERT
noise filtering); configurable
output; and an extended,
switchable temperature measurement range.
The ADT7461 can accurately measure the temperature of a
remote thermal diode to 1ꢀC and the ambient temperature to
3ꢀC. The temperature measurement range defaults to 0ꢀC to
+127ꢀC, compatible with the ADM1032, but can be switched to
a wider measurement range of−55ꢀC to +150ꢀC. The ADT7461
communicates over a 2-wire serial interface compatible with
THERM
Up to two overtemperature fail-safe
Small 8-lead SOIC or MSOP package
outputs
170 µA operating current, 5.5 µA standby current
APPLICATIONS
Desktop and notebook computers
Industrial controllers
Smart batteries
ALERT
system management bus (SMBus) standards. An
signals when the on-chip or remote temperature is out of range.
THERM
output
The
control of a cooling fan. The
THERM
output is a comparator output that allows on/off
ALERT
output can be reconfigured
output, if required.
Automotive
as a second
Enbedded systems
Burn-in applications
Instrumentation
1 Protected by U.S. Patents 5,195,827; 5,867,012; 5,982,221; 6,097,239;
6,133,753; 6,169,442; other patents pending.
CONVERSION RATE
ADDRESS POINTER
REGISTER
REGISTER
ON-CHIP
TEMPERATURE
SENSOR
LOCAL TEMPERATURE
LOW LIMIT REGISTER
LOCAL TEMPERATURE
VALUE REGISTER
LOCAL TEMPERATURE
HIGH LIMIT REGISTER
ANALOG
MUX
ADC
REMOTE TEMPERATURE
LOW LIMIT REGISTER
BUSY
RUN/STANDBY
REMOTE TEMPERATURE
HIGH LIMIT REGISTER
D+
D–
REMOTE TEMPERATURE
VALUE REGISTER
2
3
SRC
BLOCK
LOCAL THERM LIMIT
REGISTER
REMOTE OFFSET
REGISTER
EXTERNAL THERM LIMIT
REGISTER
CONFIGURATION
REGISTER
EXTERNAL DIODE OPEN-CIRCUIT
INTERRUPT
STATUS REGISTER
MASKING
ADT7461
SMBus INTERFACE
6
4
1
5
7
8
V
GND
SDATA
SCLK
THERM
ALERT/
DD
THERM2
Figure 1. Functional Block Diagram
Rev. A
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