with Two-Wire Interface
Features
SMBus interface
Programmable Trip Point (T OS ) and Hysteresis (T HYST )
Separate open-drain output pin operates as interrupt or comparator at output Register readback capability
Power up defaults permit stand-alone opera-tion as thermostat
Shutdown mode to minimize power con-sumption
Up to 8 G751s can be connected to a single bus
Key Specifications
Supply Voltage 3.0V to 5.5V Supply Current
operating 280µA (typ)
1mA (max)
shutdown 2µA(typ)
Temperature Accuracy
-25°C to 100°C ±2°C (max) -55°C to 125°C ±3°C (max)
Applications
System Thermal Management Personal Computers Office Electronics
Electronic Test Equipment
Pin Configuration
General Description
The G751 is a temperature sensor, Delta-Sigma analog-to-digital converter, and digital over- tem-perature detector with SMBus interface. The host can query the G751 at any time to read temperature. The open-drain Over temperature Shutdown (O.S.) output becomes active when the temperature ex-ceeds a programmable limit. This pin can operate in either “Comparator ” or “Interrupt ” mode.
The host can program both the temperature alarm threshold (T OS ) and the temperature at which the alarm condition goes away (T HYST ). In addition, the host can read back the contents of the G751's T OS and T HYST registers. The sensor powers up in Com-parator mode with default thresholds of 50°C T OS 45°C T HYST. for G751-1 and 80°C T OS , 75°C T HYST for G751-2.
Ordering Information ORDER NUMBER
ORDER NUMBER (Pb free)
T OS T HYST PACKAGE
令牌网
G751-1P1G751-1P1f 50°C/45°C SOP-8 G751-2P1G751-2P1f 80°C/75°C SOP-8 G751-2P8G751-2P8f 80°C/75°C MSOP-8 G751-2RD
G751-2RDf
80°C/75°C TDFN3X3-8
P1: SOP-8; P8: MSOP-8; RD: TDFN3X3-8
Typical Application
To Processor Address(Set as
Interface SMBDATA SOP-8/MSOP-8G751
+Vs A0A1A2
SMBCLK
O.S.GND
µF Interrupt Line
interrupt line
desired)
TDFN3X3-8
G751
SMBDATA SMBCLK
O.S.GND
+Vs A0A1A2
Note: Recommend connecting the Thermal Pad to the GND or let it keep floating.
Vcc to GND. . . . . . . . . . . . . . . . . . . . . . . .-0.3V to +6V SMBCLK, SMBDAT, O.S., A0, A1, A2 -0.3V to +6V SMBDATA, O.S. Current. . . . . . . . . . .-1mA to +50mA ESD Protection (human body model). . . . . . . . .2000V Continuous Power Dissipation (T A= +70°C)
SOP (derate 8.30mW/°C above +70°C) . . . . .667mW MSOP/TDFN (derate 7.14mW/°C above 70°C). . .571mW Operating Temperature Range. . . . . -55°C to +125°C Junction Temperature. . . . . . . . . . . . .. . . . . . .+150°C Storage temperature Range. . . . . . .-65°C to +165°C Reflow Temperature (soldering,10sec). . . .. . .+260°C
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the opera-tional sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
Temperature-to-Digital Converter Characteristics
Unless otherwise noted, these specifications apply for +Vs=+3.3V Vdc. Boldface limits apply for T A=T J=T MIN to T MAX; all other limits T A=T J= +25°C, unless otherwise noted.
PARAMETER CONDITIONS
TYPICAL LIMITS UNITS
Accuracy TA=-25°C to +100°C
TA=-55°C to +125°C
±2.0
±3.0
°C (max)
Resolution
9
Bits
Temperature Conversion Time 100 ms
Quiescent Current SMBus Inactive
SMBus Active
Shutdown Mode
0.25
1 1.0
mA
mA (max)
µA
O.S. Output Saturation Voltage I OUT = 4.0mA 0.8 V (max)
O.S. Delay 1
6
Conversions (min)
Conversions (max)
T OS Default Temperature G751-1/G751-2 50/80 °C
T HYST Default Temperature G751-1/G751-2 45/75 °
C
Block Diagram
A0SMBDATA
A1
A2
SMBCLK
Digital DC Characteristics
Unless otherwise noted, these specifications apply for +Vs=+3.3 Vdc. Boldface limits apply for T A =T J =T MIN to T MAX ; all other limits T A =T J =+25°C, unless otherwise noted. SYMBOL PARAMETER CONDITIONS TYPICAL LIMITS UNITS
V IN (1) Logical “1” Input Voltage +Vs × 0.7 +Vs + 0.5 V (min) V (max) V IN (0) Logical “0” Input Voltage
-0.3 +Vs ×0.3
V (min) V (max) I IN (1) Logical “1” Intput Current V IN =5V 0.005 1.0 µA I IN (0) Logical “0” Intput Current V IN =0V -0.005 -1.0 µA C IN All Digital Inputs
20
pF I OH High Level Output Current V OH =5V 100 µA (max) V OL Low Level Output Voltage I OL =3mA
0.4 V (max) t OF
Output Fall Time
C L =400pF,I O =3mA 250
ns (max)
SMBus Digital Switching Characteristics
Unless otherwise noted, these specifications apply for +Vs = +3.3 Vdc and C L (load capacitance) on output lines = 80pF unless otherwise specified. Boldface limits apply for T A = T J = T MIN to T MAX ; all other limits T A = T J = +25°C, unless otherwise noted.
The switching characteristics of the G751 fully meet or exceed the published specifications of the SMBus. The fol-lowing parameters are the timing relationships between SMBCLK and SMBDATA signals related to the G751. They are not the SMBus specifications.
SYMBOL PARAMETER CONDITIONS TYPICAL LIMITS UNITS
t 1
SMBCLK (Clock) Period
2.5 µs (min)t 2 Data in Set-Up Time to SMBCLK High
100 ns (min)t 3 Data Out Stable after SMBCLK Low 0
ns (min)t 4 SMBDATA Low Set-Up Time to SMBCLK Low (Start Condition) 100 ns (min)t 5
SMBDATA High Hold Time after SMBCLK High (Stop Condition)
100
ns (min)
Pin Description
PIN LABEL
FUNCTION TYPICAL CONNECTION
1 SMBDATA SMBus Serial Bi-Directional Data Line From Controller
2 SMBCLK SMBus Clock Input
From Controller
3
O.S.
Overtemperature Shutdown Open Drain Output
Pull Up Resistor, Controller Interrupt Line 4 GND Power Supply Ground Ground
5,6,7 A0-A2 User-Set SMBus Address Inputs Ground (Low, “0”) or +Vs (High, “1”) 8 +Vs Positive Supply Voltage Input
DC Voltage from 3V to 5.5V
Thermal Pad Recommend connecting the Thermal Pad to the
GND or let it keep floating.
SMBDATA
SMBDATA SMBCLK
Data in
虹膜识别Data out
Temperature-to-Digital Transfer Function (Non-linear scale for clarity)
Functional Description
The G751 temperature sensor incorporates a band-gap type temperature sensor and 9-bit ADC (Delta-Sigma Analog- to-Digital Converter). The tem-perature data output of the G751 is available at all times via the SMBus. If a conversion is in progress, it will be stopped and restarted after the read. A digital comparator is also incorporated that compares a se-ries of readings, the number of which is user-selectable, to user-programmable setpoint and hysteresis values. The comparator trips the O.S. out-put line, which is programmable for mode and polarity. O.S. Output, T OS and T HYST Limits
In Comparator mode the O.S. Output behaves like a thermostat. The output becomes active when tem-perature exceeds the T OS limit, and leaves the active state when the temperature drops below the T HYST limit. In this mode the O.S. output can be used to turn a cooling fan on, initiate an emergency system shutdown, or reduce system clock speed. Shutdown mode does not reset O.S. state in a comparator mode.
In interrupt mode exceeding T OS also makes O.S. active but O.S. will remain active indefinitely until
reset by reading any register via the SMBus inter-face. Once O.S. has been activated by crossing T OS, then reset, it can activated again only by Tempera-ture going below T HYST. Again, it will remain active indefinitely until being reset by a read. Placing the G751 in shutdown mode also resets the O.S. output. Default Modes
G751 always powers up in a known state. G751 power up default conditions are:
1. Comparator mode
2. T OS set to 50°C for G751-1, to 80°C for G751-2
3. T HYST set to 45°C for G751-1, to 75°C for G751-2
4. O.S. active low
傲世九重天起点
5. Pointer set to “00”; Temperature Register
With these operating conditions G751 can act as a stand-alone thermostat with the above temperature settings. Connection to an SMBus is not required.
SMBus Interface
The G751 op erates as a slave on the SMBus, so
the SMBCLK line is an input (no clock is generated
by the G751) and the SMBDATA line is a
bi-directional serial data path. According to SMBus specifications, the G751 has a 7-bit slave address.
The four most significant bits of the slave address
are hard wired inside the G751 and are “1001”. The three least significant bits of the address are as-signed to pins A2-A0, and are set by connecting these pins to ground for a low, (0); or to +Vs for a high, (1).
Therefore, the complete slave address is:
1 0 0 1 A
2 A1 A0 MSB LSB
Figure1 O.S. Output Temperature Response Dia-gram
Temperature Data Format
我们约会吧2013Temperature data can be read from the Temperature, T OS Set Point, and T HYST Set Point registers; and written to the T OS Set Point, and T HYST Set Point reg-isters. Temperature data is represented
by a 9-bit, two’s complement word with an LSB (Least Significant Bit) equal to 0.5°C:
DIGITAL OUTPUT
TEMPERATURE
BINARY HEX
+125°C 0 1111 1010
0FAh +25°C 0 0011 0010 032h +0.5°C 0 0000 0001 001h 0°C 0 0000 0000 000h -0.5°C 1 1111 1111 1FFh -25°C 1 1100 1110 1CEh -55°C
1 1001 0010
192h
Shutdown Mode
Shutdown mode is enabled by setting the shutdown bit in the Configuration register via the SMBus. Shut-down mode reduces power supply current to 1µA typical. In interrupt mode O.S. is reset if previously set and is undefined in Compatator mode during shutdown. The SMBus interface remains active. Ac-tivity on the clock and data lines of the SMBus may slightly increase shutdown mode quiescent current. T OS , T HYST , and Configuration registers can be read from and written to in shutdown mode.
Fault Queue
A fault queue of up to 6 faults is provided to prevent false tripping of O.S. when the G751 is used in noisy environments. The number of faults set in the queue must occur consecutively to set the O.S. output. Comparator/Interrupt Mode
As indicated in the O.S. Output Temperature Re-sponse Diagram, Figure 1, the events that trigger O.S. are identical for either Comparator or Interrupt mode. The most important difference is that in Inter-rupt mode the O.S. will remain set indefinitely once it has been set. To reset O.S. while in Interrupt mode, perform a read from any register in the G751. O.S. Output
The O.S. output is an open-drain output and does not have an internal pull-up. A ”high ” level will not be observed on this pin until pull-up current is provided from some external source, typically a pull-up resis-tor. Choice of resistor value depends on many sys-tem factors but, in general, the pull-up resistor should be as large as possible. This will minimize any errors due to internal heating of the G751. The maximum resistance of the pull up, based on G751 specification for High Level Output Current, to pro-vide a 2V high level, is 30k Ω.
O.S. Polarity
The O.S. output can be programmed via the con-figuration register to be either active low (default mode), or active high. In active low mode the O.S. output goes low when triggered exactly as shown on the O.S. Output Temperature Response Diagram, Figure 1. Active high simply inverts the polarity of the O.S. output.
T T O S
T H Y S T
O .S .
(C o m p a r a t o r M o d e )
O .S .
(I n t e r r u p t M o d e )
全宋词检索e m p e r a t u S h o w n
f o r O .S . s e t f o r a c t i v e l o w .
*r e a d a n y r e g i s t e r o r p l a c e d i n s h u t d o w n
热看网
There are four data registers in the G751, selected by the Pointer register. At power-up the Pointer is set to “00”; the location for the Temperature Register. The Pointer register latches whatever the last loca-tion it was set to. In Interrupt Mode, a read from the G751, or placing the device in shutdown mode, re-sets the O.S. output. All registers are read and write, except the Temperature register which is read only. A write to the G751 will always include the address byte and the Pointer byte. A write to the Configura-tion register requires one data byte, and the T OS and T HYST registers require two data bytes.
Reading the G751 can take place either of two ways: If the location latched in the Pointer is correct (most of the time it is expected that the Pointer will point to Temperature register because it will be the data most frequently read from the G751), then the read can simply consist of an address byte, followed by retrieving the corresponding number of data bytes. If the Pointer needs to be set, than an address byte, pointer byte, repeat start, and another address byte will accomplish a read.
The first data byte is the most significant byte with most signification bit first, permitting only as much data as necessary to be read to determine tempera-ture condition. For instance, if the first four bits of the temperature data indicates an overtemperature con-dition, the host processor could immediately take action to remedy the excessive temperatures. At the end of a read, the G751 can accept either Acknowl-edge or No Acknowledge from the Master (No Ac-knowledge is typically used as a signal for the salve that the Master has read its last byte).
An inadvertent 8-bit read from a 16-bit register, with the D7 bit low, can cause the G751 to stop in a state where the SDA line is held low as shown in Figure 2. This can prevent any further bus communication until at least 9 additional clock cycles have occurred. Al-ternatively, the master can issue clock cycles until SDA goes high, at which time issuing a ״Stop ״ condition will reset the G751.
Figure 2. Inadvertent 8-Bit Read from 16-Bit Register where D7 is Zero
Master but G751 locks SMBDATA low Master detects the error
SMBCLK
SMBDATA
Intended Stop by
of its ways
