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零件编号 | G767 | ||
描述 | Remote/Local Temperature Sensor | ||
制造商 | GMT | ||
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1 Page
Global Mixed-mode Technology Inc.
G767
Remote/Local Temperature Sensor with SMBus
Serial Interface
Features
Two Channels: Measures Both Remote and
Local Temperatures
No Calibration Required
SMBus 2-Wire Serial Interface
Programmable Under/Overtemperature Alarms
Supports SMBus Alert Response
Accuracy:
±2°C (+60°C to + 100°C, local)
±3°C (-40°C to +125°C, local)
±3°C (+60°C to +100°C, remote)
3µA (typ) Standby Supply Current
70µA (max) Supply Current in Auto- Convert
Mode
+3V to +5.5V Supply Range
Small, 16-Pin SSOP Package
Applications
Desktop and Notebook
Computers
Smart Battery Packs
LAN Servers
Industrial Controls
Central Office
Telecom Equipment
Test and Measurement
Multi-Chip Modules
Pin Configuration
General Description
The G767 is a precise digital thermometer that reports
the temperature of both a remote sensor and its own
package. The remote sensor is a diode-connected
transistor typically a low-cost, easily mounted 2N3904
NPN type-that replace conventional thermistors or
thermocouples. Remote accuracy is ±3°C for multiple
transistor manufacturers, with no calibration needed.
The remote channel can also measure the die tem-
perature of other ICs, such as microprocessors, that
contain an on-chip, diode-connected transistor.
The 2-wire serial interface accepts standard System
Management Bus (SMBusTM) Write Byte, Read Byte,
Send Byte, and Receive Byte commands to program
the alarm thresholds and to read temperature data.
The data format is 7 bits plus sign, with each bit cor-
responding to 1°C, in two’s-complement format.
Measurements can be done automatically and
autonomously, with the conversion rate programmed
by the user or programmed to operate in a single-shot
mode. The adjustable rate allows the user to control
the supply-current drain.
The G767 is available in a small, 16-pin SSOP sur-
face-mount package.
Ordering Information
ORDER ORDER NUMBER
NUMBER (Pb free)
TEMP.
RANGE
PACKAGE
G767
G767f
-55°C to +125°C SSOP-16
Typical Operating Circuit
N.C. 1
Vcc 2
DXP 3
DXN 4
N.C. 5
ADD1 6
GND 7
GND 8
G767
SSOP-16
16 N.C
15 STBY
14 SMBCLK
13 N.C.
12 SMBDATA
11 ALERT
10 ADD0
9 N.C.
0.1 µF
3V TO 5.5V
200Ω
2N3904
Vcc STBY
DXP
DXN
2200pF
SMBCLK
SMBDATA
ALERT
ADD0 ADD1 GND
10k EACH
CLOCK
DATA
INTERRUPT
TO µC
Ver: 2.5
Dec 14, 2004
TEL: 886-3-5788833
http://www.gmt.com.tw
1
Global Mixed-mode Technology Inc.
G767
Write Byte Format
S ADDRESS
WR
ACK
COMMAND
ACK
DATA
ACK
P
7 bits
8 bits
8 bits
1
Slave Address: equivalent to chip- select line of a 3-wire interface
Command Byte: selects which register you are writing to
Data byte: data goes into the register set by the command byte (to set thresholds, configuration masks, and sam
pling rate)
Read Byte Format
S ADDRESS WR ACK COMMAND ACK S
7 bits
8bits
Slave Address: equivalent to chip- select line
Command Byte: selects which register you are reading from
Slave Address: repeated due to change in data-flow direction
Data byte: reads from the register set by the command byte
ADDRESS
7bits
RD
ACK
DATA
8 bits
/// P
Send Byte Format
S ADDRESS
WR
ACK
COMMAND
ACK
7 bits
8 bits
Command Byte: sends command with no data , usually used for one-shot command
P
Receive Byte Format
S ADDRESS
RD
ACK
DATA
///
P
7 bits
8 bits
Data Byte: reads data from the register commanded by the last Read Byte or Write Byte transmission; also used
for SMBus Alert Response return address
S = Start condition Shaded = Slave transmission P = Stop condition /// = Not acknowledged
Figure 3. SMBus Protocols
Table 2. Data Format (Twos-Complement)
TEMP.
(°C)
ROUND
TEMP.
(°C)
DIGITAL OUTPUT
DATA BITS
SIGN MSB LSB
+130.00
+127
0
111 1111
+127.00
+127
0
111 1111
+126.50
+127
0
111 1111
+126.00
+126
0
111 1110
+25.25
+25
0 001 1001
+0.50
+1
0 000 0001
+0.25
+0
0 000 0000
+0.00
+0
0 000 0000
-0.25
+0
0 000 0000
-0.50
+0
0 000 0000
-0.75
-1
1 111 1111
-1.00
-1
1 111 1111
-25.00
-25
1 110 0111
-25.50
-25
1 110 0110
-54.75
-55
1 100 1001
-55.00
-55
1 100 1001
-65.00
-65
1 011 1111
-70.00
-65
1 011 1111
Alarm Threshold Registers
Four registers store alarm threshold data, with
high-temperature (THIGH) and low-temperature (TLOW)
registers for each A/D channel. If either measured
temperature equals or exceeds the corresponding
alarm threshold value, an ALERT interrupt is as-
serted.
The power-on-reset (POR) state of both THIGH registers
is full scale (0111 1111, or +127°C). The POR state of
both TLOW registers is 1100 1001 or -55°C.
Diode Fault Alarm
There is a continuity fault detector at DXP that detects
whether the remote diode has an open-circuit condi-
tion. At the beginning of each conversion, the diode
fault is checked, and the status byte is updated. This
fault detector is a simple voltage detector; if DXP rises
above VCC – 1V (typical) due to the diode current
source, a fault is detected. Note that the diode fault
isn’t checked until a conversion is initiated, so immedi-
ately after power-on reset the status byte indicates no
fault is present, even if the diode path is broken.
Ver: 2.5
Dec 14, 2004
TEL: 886-3-5788833
http://www.gmt.com.tw
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页数 | 14 页 | ||
下载 | [ G767.PDF 数据手册 ] |
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