GMT G767 Datasheet
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 Central Office
Computers Telecom Equipment
Smart Battery Packs Test and Measurement
LAN Servers Multi-Chip Modules
Industrial Controls
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 temperature of other ICs, such as microprocessors, that
contain an on-chip, diode-connected transistor.
The 2-wire serial interface accepts standard System
Management Bus (SMBus
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 corresponding 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 surface-mount package.
TM
) Write Byte, Read Byte,
Ordering Information
Part* Temp. range Pin-package
G767 -55°C to +125°C 16-SSOP
Pin Configuration Typical Operating Circuit
G767
N.C.
Vcc
DXP
DXN
N.C.
ADD1
GND
GND
1
2
3
4
5
6
7
8
16Pin SSOP
16
15
14
13
12
11
10
9
N.C
STBY
SMBCLK
N.C.
SMBDATA
ALERT
ADD0
N.C.
2N3904
0.1 µF
2200pF
STBY
Vcc
DXP
DXN
ADD0 ADD1 GND
SMBCLK
SMBDATA
ALERT
200
3V TO 5.5V
Ω
10k EACH
CLOCK
DATA
INTERRUPT
TO µC
Ver 2.2
Nov 07, 2001
1
TEL: 886-3-5788833
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Global Mixed-mode Technology Inc.
Absolute Maximum Ratings
Vcc to GND………….….……..………….-0.3V to +6V
DXP, ADD to GND……….…….…-0.3V to (Vcc + 0.3V)
DXN to GND……………..……………..-0.3V to +0.8V
SMBCLK, SMBDATA,
……………………………………………..…-0.3V to +6V
SMBDATA,
ALERT Current………….-1mA to +50mA
DXN Current……………………..………………….±1mA
ESD Protection (SMBCLK, SMBDATA,
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 operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may
affect device reliability.
ALERT , STBY to GND…………
ALERT , human
body model).………………………………………..4000V
ESD Protection (other pins, human body model)..2000V
Continuous Power Dissipation (T
(derate 8.30mW/°C above +70°C)…………......667mW
Operating Temperature Range………-55°C to +125°C
Junction Temperature………………….………..+150°C
Storage temperature Range………….-65°C to +165°C
Lead Temperature (soldering, 10sec)……..……...+300°C
G767
= +70°C) SSOP
A
Electrical Characteristics
(Vcc = + 3.3V, TA = 0°C to +85°C, unless otherwise noted.)
PARAMETER CONDITIONS MIN TYP MAX UNITS
ADC and power supply
Temperature Resolution (Note 1) Monotonicity guaranteed 8 Bits
TA = +60°C to +100°C -2 2 Initial Temperature Error,
Local Diode (Note 2)
ode (Notes 2 and 3)
(Notes 1 and 2)
Supply-Voltage Range 3.0 5.5 V
Undervoltage Lockout Threshold Vcc input, disables A/D conversion, rising edge 2.6 2.8 2.95 V
Undervoltage Lockout Hysteresis 50 mV
Power-On Reset Threshold Vcc , falling edge 1.0 1.7 2.5 V
POR Threshold Hysteresis 50 mV
Standby Supply Current
Average Operating Supply
Current
Conversion Time From stop bit to conversion complete(both channels) 94 125 156 ms
Conversion Rate Timing Error Auto-convert mode -25 25 %
Remote-Diode Source Current
Address Pin Bias Current ADD0, ADD1; momentary upon power-on reset 160 µA
= 0°C to +85°C -3 3
T
A
TR = +60°C to +100°C -3 3 Temperature Error, Remote Di-
= -55°C to +125°C -5 5
T
R
Including long-term drift
Logic inputs forced
to Vcc or GND
Auto-convert mode,average measured over 4sec. Logic inputs forced
to Vcc or GND
DXP forced to 1.5V
TA = +60°C to +100°C -2.5 2.5 Temperature Error, Local Diode
= 0°C to +85°C -3.5 3.5
T
A
SMBus static 3 10
Hardware or software
standby, SMBCLK at 10kHz
0.25 conv/sec 35 70
2.0 conv/sec 120 180
High level 80 100 120
Low level 8 10 12
4
°C
°C
°C
µA
µA
µA
Ver 2.2
Nov 07, 2001
2
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Global Mixed-mode Technology Inc.
Electrical Characteristics
(Vcc = + 3.3V, T
= 0 to +85°C, unless otherwise noted.)
A
(continued)
G767
PARAMETER CONDITIONS MIN TYP MAX UNITS
SMBus Interface
, SMBCLK, SMBDATA; Vcc = 3V to 5.5V
Logic Input High Voltage
Logic Input Low Voltage
Logic Output Low Sink Current
ALERT
Logic Input Current Logic inputs forced to Vcc or GND -1 1 µA
SMBus Input Capacitance SMBCLK, SMBDATA 5 pF
SMBus Clock Frequency (Note 4) DC 100 kHz
SMBCLK Clock Low Time t
SMBCLK Clock High Time t
SMBus Start-Condition Setup Time 4.7 µs
SMBus Repeated Start-Condition Setup Time t
SMBus Start-Condition Hold Time t
SMBus Start-Condition Setup Time t
SMBus Data Valid to SMBCLK Rising-Edge
Time
SMBus Data-Hold Time t
SMBCLK Falling Edge to SMBus Data-Valid
Time
Output High Leakage Current
STBY
, SMBCLK, SMBDATA; Vcc = 3V to 5.5V
STBY
ALERT
ALERT
t
SMBCLK
Master clocking in data 1 µs
, SMBDATA forced to 0.4V
forced to 5.5V
, 10% to 10% points 4.7 µs
LOW
, 90% to 90% points 4 µs
HIGH
90% to 90% points 500 ns
SU : STA ,
10% of SMBDATA to 90% of SMBCLK 4 µs
HD: STA ,
90% of SMBDATA to 10% of SMBDATA 4 µs
SD: STO ,
10% or 90% of SMBDATA to 10% of
SU: DAT ,
(Note 5) 0 µs
HD : DAT
2.2 V
0.8 V
6 mA
1 µA
800 ns
Electrical Characteristics
(Vcc = + 3.3V, TA = -5.5 to + 125°C, unless otherwise noted.) (Note 6)
PARAMETER CONDITIONS MIN TYP MAX UNITS
ADC and power supply
Temperature Resolution (Note 1) Monotonicity guaranteed 8 Bits
TA = +60°C to +100°C -2 2 Initial Temperature Error, Local
Diode (Note 2)
(Notds2 and 3)
Supply-Voltage Range 3.0 5.5 V
Conversion Time From stop bit to conversion complete (both channels) 94 125 156 ms
Conversion Rate Timing Error Auto-convert mode -25 25 %
SMBus Interface
Logic Input High Voltage STBY, SMBCLK, SMBDATA
Logic Input Low Voltage STBY, SMBCLK, SMBDATA; Vcc = 3V to 5.5V 0.8 V
Logic Output Low Sink Current ALERT, SMBDATA forced to 0.4V 6 mA
ALERT
Logic Input Current Logic inputs forced to Vcc or GND -2 2 µA
Note1:
Note2:
Output High Leakage Current
Guaranteed but not 100% tested.
Quantization error is not included in specifications for temperature accuracy. For example, if the G767 de-
= -55°C to +125°C -3 3
T
A
TR = +60°C to +100°C -3 3 Temperature Error, Remote Diode
= -55°C to +125°C -5 5
T
R
Vcc = 3V 2.2
Vcc = 5.5V 2.4
ALERT forced to 5.5V 1 µA
vice temperature is exactly +66.7°C, or +68°C (due to the quantization error plus the +1/2°C offset used for
rounding up) and still be within the guaranteed ±1°C error limits for the +60°C to 100°C temperature range.
See Table2.
Note3:
A remote diode is any diode-connected transistor from Table1. T
is the junction temperature of the remote
R
of the remote diode. See Remote Diode Selection for remote diode forward voltage requirements.
Note4:
The SMBus logic block is a static design that works with clock frequencies down to DC. While slow operation is
possible, it violates the 10kHz minimum clock frequency and SMBus specifications, and may monopolize the bus.
Note5:
Note that a transition must internally provide at least a hold time in order to bridge the undefined region
(300ns max) of SMBCLK’s falling edge.
Note6:
Ver 2.2
Nov 07, 2001
Specifications from -55°C to +125°C are guaranteed by design, not production tested.
http://www.gmt.com.tw
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TEL: 886-3-5788833
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°C
V
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Pin Description
PIN NAME FUNCTION
1,5,9,13,16 N.C. No Connection. Not internally connected. May be used for PC board trace routing
2 Vcc
3 DXP
4 DXN Combined Current Sink and A/D Negative Input.
6 ADD1
7,8 GND Ground
10 ADD0 SMBus Slave Address Select pin
11
12 SMBDATA SMBus Serial-Data Input / Output , open drain
14 SMBCLK SMBus Serial-Clock Input
15
ALERT
STBY
Detailed Description
The G767 (patents pending) is a temperature sensor
designed to work in conjunction with an external microcontroller (µC) or other intelligence in thermostatic,
process-control, or monitoring applications. The µC is
typically a power-management or keyboard controller,
generating SMBus serial commands by “bit-banging”
general-purpose input-output (GPIO) pins or via a
dedicated SMBus interface block.
Essentially an 8-bit serial analog-to digital converter
(ADC) with a sophisticated front end, the G767 contains a switched current source, a multiplexer, an ADC,
an SMBus interface, and associated control logic (Figure 1). Temperature data from the ADC is loaded into
two data registers, where it is automatically compared
with data previously stored in four over/under- temperature alarm registers.
ADC and Multiplexer
The ADC is an averaging type that integrates over a
Supply Voltage Input , 3V to 5.5V. Bypass to GND with a 0.1µF capacitor. A 200
recommended but not required additional noise filtering.
Combined Current Source and A/D Positive Input for remote-diode channel. Do not leave DXP floating; tie DXP to DXN if no remote diode is used. Place a 2200pF capacitor between DXP and DXN for
noise filtering.
SMBus Address Select pin (Table 8). ADD0 and ADD1 are sampled upon power-up. Excess capacitance (>50pF) at the address pins when floating may cause address-recognition problems.
SMBus Alert (interrupt) Output, open drain
Hardware Standby Input. Temperature and comparison threshold data are retained in standby mode.
Low = standby mode, high = operate mode.
60ms period (each channel, typical), with excellent
noise rejection.
The multiplexer automatically steers bias currents
through the remote and local diodes, measures their
forward voltages, and computes their temperatures.
Both channels are automatically converted once the
conversion process has started, either in free-running
or single-shot mode. If one of the two channels is not
used, the device still performs both measurements,
and the user can simply ignore the results of the unused channel. If the remote diode channel is unused,
tie DXP to DXN rather than leaving the pins open.
The worst-case DXP-DXN differential input voltage
range is 0.25V to 0.95V.
Excess resistance in series with the remote diode
causes about +1/2°C error per ohm. Likewise, 200µV
of offset voltage forced on DXP-DXN causes about
1°C error.
G767
series resistor is
Ω
Ver 2.2
Nov 07, 2001
4
TEL: 886-3-5788833
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DXP
DXN
Global Mixed-mode Technology Inc.
V
CC
MUX
+
+
REMOTE
LOCAL
DIODE
FAULT
+
ADC
CONTROL
LOGIC
STBY
2
ADD0
ADDRESS
DECODER
SMBUS
READ
8
ADD1
WRITE
G767
7
SMBDATA
SMBCLK
8
REMOTE TEMPERAT URE
8
DATA REGISTER
HIGH-TEMPETATURE
8
ALERT
THRESHOLD (REMOTE
LOW-TEMPETATURE
THRESHOLD (REMOTE
DIGITAL COMPARATOR
(REMOTE)
S
Q
R
HIGH
)
)
LOW
THRESHOLD (LOCALT
THRESHOLD (LOCAL T
Figure 1. Functional Diagram
A/D Conversion Sequence
If a Start command is written (or generated automatically in the free-running auto-convert mode), both
channels are converted, and the results of both measurements are available after the end of conversion. A
BUSY status bit in the status byte shows that the device is actually performing a new conversion; however,
even if the ADC is busy, the results of the previous
conversion are always available.
LOCAL EMPERATURE
DATA REGISTER
HIGH-TEMPETATURE
LOW-TEMPETATURE
8
DIGITAL COMPARATOR
(LOCAL)
SELECTED VIA
SLAVE ADD = 0001 100
HIGH
)
)
LOW
8
8
COMMAND BYTE
(INDEX) REGISTER
STATUS BYTE
REGISTER
CONFIGURATION
BYTE REGISTER
CONVERSION RATE
REGISTER
ALERT RESPONSE
ADDRESS REGISTER
this is true at the highest expected temperature. The
forward voltage must be less than 0.95V at 100µA;
check to ensure this is true at the lowest expected
temperature. Large power transistors don’t work at all.
Also, ensure that the base resistance is less than
100Ω. Tight specifications for forward-current gain
(+50 to +150, for example) indicate that the manufacturer has good process controls and that the devices
have consistent VBE characteristics.
Remote-Diode Selection
Temperature accuracy depends on having a
good-quality, diode-connected small-signal transistor.
Accuracy has been experimentally verified for all of the
devices listed in Table 1. The G767 can also directly
measure the die temperature of CPUs and other integrated circuits having on-board temperature-sensing
diodes.
The transistor must be a small-signal type with a relatively high forward voltage; otherwise, the A/D input
voltage range can be violated. The forward voltage
must be greater than 0.25V at 10µA; check to ensure
Ver 2.2
Nov 07, 2001
Thermal Mass and Self-Heating
Thermal mass can seriously degrade the G767’s effective accuracy. The thermal time constant of the
SSOP-16 package is about 140sec in still air. For the
G767 junction temperature to settle to within +1°C
after a sudden +100°C change requires about five
time constants or 12 minutes. The use of smaller
packages for remote sensors, such as SOT23s, improves the situation. Take care to account for thermal
gradients between the heat source and the sensor,
and ensure that stray air currents across the sensor
package do not interfere with measurement accuracy.
TEL: 886-3-5788833
http://www.gmt.com.tw
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