ADT7461 Datasheet, PDF (1/24 Pages) Analog Devices – ±1°C Temperature Monitor with Series Resistance Cancellation

±1°C Temperature Monitor with
Series Resistance Cancellation
ADT7461*
FEATURES
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
Up to 2 overtemperature fail-safe THERM outputs
Small 8-lead SOIC or MSOP package
170 µA operating current, 5.5 µA standby current
APPLICATIONS
Desktop and notebook computers
Industrial controllers
Smart batteries
Automotive
Enbedded systems
Burn-in applications
Instrumentation
PRODUCT DESCRIPTION
The ADT7461 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
noise filtering; configurable ALERT output; and an extended,
switchable temperature measurement range.
The ADT7461 can measure the temperature of a remote ther-
mal diode accurate to ±1°C, and the ambient temperature accu-
rate to ±3°C. The temperature measurement range defaults to
0°C to +127°C, compatible with ADM1032, but can be switched
to a wider measurement range, from −55°C to +150°C. The
ADT7461 communicates over a 2-wire serial interface compati-
ble with system management bus (SMBus) standards. An
ALERT output signals when the on-chip or remote temperature
is out of range. The THERM output is a comparator output that
allows on/off control of a cooling fan. The ALERT output can
be reconfigured as a second THERM output if required.
*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.
ON-CHIP
TEMPERATURE
SENSOR
CONVERSION RATE
REGISTER
LOCAL TEMPERATURE
VALUE REGISTER
D+ 2
D– 3
ANALOG
MUX
ADC
SRC
BLOCK
BUSY
RUN/STANDBY
REMOTE TEMPERATURE
VALUE REGISTER
REMOTE OFFSET
REGISTER
EXTERNAL DIODE OPEN-CIRCUIT
ADT7461
1
V_DD
5
GND
STATUS REGISTER
SMBus INTERFACE
7
SDATA
8
SCLK
Figure 1. Functional Block Diagram
ADDRESS POINTER
REGISTER
LOCAL TEMPERATURE
LOW LIMIT REGISTER
LOCAL TEMPERATURE
HIGH LIMIT REGISTER
REMOTE TEMPERATURE
LOW LIMIT REGISTER
REMOTE TEMPERATURE
HIGH LIMIT REGISTER
LOCAL THERM LIMIT
REGISTER
EXTERNAL THERM LIMIT
REGISTER
CONFIGURATION
REGISTER
INTERRUPT
MASKING
4
THERM
6
ALERT/
THERM2
Rev. 0
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