MC74A5-33SNTR [ONSEMI]
Serial Digital Temperature Sensor; 串行数字温度传感器型号: | MC74A5-33SNTR |
厂家: | ONSEMI |
描述: | Serial Digital Temperature Sensor |
文件: | 总12页 (文件大小:126K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
The MC74 is a serial digital temperature sensor suited for low cost
applications. Temperature data is converted from the integrated thermal
sensing element and made available as an 8–bit serial digital word.
Communication with the MC74 is accomplished via 2–wire
SMBus/I2C–compatible serial port. Temperature resolution is 1°C.
Conversion rate is a nominal 8 samples/sec. Power consumption is
only 200 µA (5 µA Standby).
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Features
• Tested Operating Temperature Range: –40°C to +125°C
• Simple Serial Port Interface
• Solid State Temperature Sensing:
±2°C Accuracy from +25°C to +85°C
±3°C Accuracy from 0°C to +125°C
SOT–23–5
SN SUFFIX
CASE TBD
PRELIMINARY INFORMATION
• 3.3V and 5.5V Versions
PIN CONFIGURATION
(Top View)
Typical Applications
• Thermal Protection for Hard Disk Drives and Other PC Peripherals
• Low–Cost Thermostat Controls
• Power Supplies
5
4
1
2
SDA
SCL
NC
GND
FUNCTIONAL BLOCK DIAGRAM
3
V
DD
Serial Port
Interface
Internal Sensor
(Diode)
SDA
SCL
SOT–23–5*
NOTE: *SOT–23–5 is equivalent to EIAJ–SC74A
Modulator
Control
Logic
Temperature
Register
1
5
TO–220–5
T SUFFIX
CASE TBD
PRELIMINARY INFORMATION
ORDERING INFORMATION
Device
Package
Voltage
MC74A5–33SNTR
SOT–23–5
3.3V V
DD
DD
MC74A5–50T
TO–220–5
5.0V V
Semiconductor Components Industries, LLC, 1999
1
Publication Order Number:
February, 2000 – Rev. 0
MC74/D
MC74
PIN DESCRIPTION FOR TO–220–5
Pin No.
Symbol
NC
Type
None
Description
1
2
3
4
5
Not Connected
SDA
GND
SCL
Bi–directional
Power
SMBus Serial Data
System Ground
Input
SMBus Serial Clock
Power Supply Input
V
DD
Power
PIN DESCRIPTION FOR SOT–23–5
Pin No.
Symbol
NC
Type
None
Description
1
2
3
4
5
Not Connected
GND
Power
System Ground
V
DD
Power
Power Supply Input
SMBus Serial Clock
SMBus Serial Data
SCL
SDA
Input
Bi–directional
PIN DESCRIPTION
SCL
V
DD
Input. SMBus serial clock. Clocks data into and out of the
MC74.SeeSystemManagementBusSpecification, rev. 1.0,
for timing diagrams.
Input. Power supply input. See electrical specifications.
GND
Input. Ground return for all MC74 functions.
SDA
Bi–directional. Serial data is transferred on the SMBus in
both directions using this pin. See System Management Bus
Specification rev. 1.0 for timing diagrams.
ABSOLUTE MAXIMUM RATINGS*
Symbol
DD
Parameter
Value
6.0
Unit
V
V
Power Supply Voltage
Voltage on Any Pin
(GND – 0.3 V) to (V
+ 0.3 V)
V
DD
T
Operating Temperature Range
Storage Temperature Range
Current on Any Pin
–40 to +125
–65 to +150
±50
°C
A
T
stg
°C
mA
mW
P
Maximum Power Dissipation
330
D
* Maximum Ratings are those values beyond which damage to the device may occur.
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2
MC74
(5)
= 3.3 V or 5.0V , –40°C ≤ T ≤ 125°C, unless otherwise noted.)
DC ELECTRICAL CHARACTERISTICS (V
DD
Characteristic
A
Symbol
Min
Typ
Max
Unit
Power Supply
V
Power–On Reset Threshold
(V Falling Edge or Rising Edge)
V
A
A
POR
1.2
—
—
200
5.0
2.2
350
10
DD
Operating Current
(V = 5.5V, Serial Port Inactive)
I
I
DD
(1)
DD
Standby Supply Current
(V = 3.3 V, Serial Port Inactive)
DD–STANDBY
(4)
—
DD
Temperature–to–Bits Converter
Temperature Accuracy MC74A
+25°C ≤ T ≤ +85°C
T
ERR
°C
–2.0
–3.0
—
—
—
±2.0
+2.0
+3.0
—
A
0°C ≤ T ≤ +125°C
A
–40°C ≤ T ≤ 0°C
A
(2)
CR
Conversion Rate
4.0
8.0
—
sa/sec
Serial Port Interface
V
V
V
Logic Input High
Logic Input Low
0.8 x V
—
—
—
—
V
V
V
IH
DD
0.2 x V
IL
DD
SDA Output Low
(3)
OL
—
—
—
—
0.4
0.6
I
I
= 3 mA
= 6 mA
OL
OL
(3)
C
Input Capacitance SDA, SCL
I/O Leakage
—
5.0
0.1
—
pF
A
IN
I
–1.0
1.0
LEAK
1. Operating current is an average value integrated over multiple conversion cycles. Transient current may exceed this specification.
2. Maximum guaranteed conversion time after Power–On RESET (POR to DATA_RDY) is 250 msec.
3. Output current should be minimized for best temperature accuracy. Power dissipation within the MC74 will cause self–heating and
temperature drift error.
4. SDA and SCL must be connected to V
or GND.
DD
=5.0VforMC74A5–50T. AllparttypesoftheMC74willoperateproperlyoverthewiderpowersupply
5. V
=3.3VforMC74A5–33SNTR. V
DD
DD
range of 2.7V to 5.5V. Each part type is tested and specified for rated accuracy at its nominal supply voltage. As V
varies from the nominal
DD
value, accuracy will degrade 1°C/V of V
change.
DD
SERIAL PORT AC TIMING (V
= 3.3 V or 5.0V, –40°C ≤ (T = T ) ≤ 125°C; C = 80 pF unless otherwise noted.)
A J L
DD
Symbol
Characteristic
SMBus Clock Frequency
Min
10
Typ
—
Max
100
—
Unit
kHz
sec
f
t
t
t
t
t
SMB
Low Clock Period (10% to 10%)
High Clock Period (90% to 90%)
SMBus Rise Time (10% to 90%)
SMBus Fall Time (90% to 10%)
4.7
4.0
—
—
LOW
—
—
sec
HIGH
—
1,000
300
—
nsec
nsec
sec
R
—
—
F
Start Condition Setup Time (90% SCL to 10% SDA)
(for Repeated Start Condition)
4.0
—
SU(START)
t
t
t
t
t
t
Start Condition Hold Time
Data in Setup Time
4.0
1,000
1,250
4.0
—
—
—
—
—
—
—
—
sec
nsec
nsec
sec
H(START)
SU–DATA
H–DATA
SU(STOP)
IDLE
Data in Hold Time
—
Stop Condition Setup Time
Bus Free Time Prior to New Transition
—
4.7
—
sec
Power–On Reset Delay (V
≥ V
DD POR
(Rising Edge))
—
500
sec
POR
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3
MC74
DETAILED OPERATING DESCRIPTION
MC74 Serial Bus Conventions
Term Explanation
The MC74 acquires and converts temperature
information from its integrated solid state sensor with a
basic accuracy of ±1°C . It stores the data in an internal
register which is read through the serial port. The system
interface is a slave SMBus. The temperature data can be
read at any time through the SMBus port. Eight SMBus
addressesareprogrammablefortheMC74, whichallowsfor
a multi–sensor configuration. Also, there is low–power
Standby mode where temperature acquisition is suspended.
Transmitter The device sending data to the bus.
Receiver The device receiving data from the bus.
Master
The device which controls the bus: initiating
transfers (START), generating the clock, and
terminating transfers (STOP).
Slave
Start
The device addressed by the master.
A unique condition signaling the beginning
of a transfer indicated by SDA falling (High
— Low) while SCL is high.
Standby Mode
The MC74 allows the host to put it into a low power (IDD
= 5µA, typical) Standby mode. In this mode, the A/D
converter is halted and the temperature data registers are
frozen. The SMBus port operates normally. Standby mode
is enabled by setting the SHDN bit in the CONFIG register.
The table below summarizes this operation.
Stop
ACK
A unique condition signaling the end of a
transfer indicated by SDA rising (Low —
High) while SCL is high.
A receiver acknowledges the receipt of
each byte with this unique condition. The
receiver drives SDA low during SCL high
of the ACK clock–pulse. The Master pro-
vides the clock pulse for the ACK cycle.
Standby Mode Operation
SHDN Bit
Operating Mode
Normal
0
1
Busy
Communication is not possible because
the bus is in use.
Standby
NOT Busy When the bus is idle, both SDA and SCL
will remain high.
SMBus Slave Address
The MC74 is internally programmed to have a default
SMBus address value of 1001 101b. Seven other addresses
are available by custom order (contact factory).
Data Valid The state of SDA must remain stable dur-
ing the High period of SCL in order for a
data bit to be considered valid. SDA only
changes state while SCL is low during nor-
mal data transfers (see Start and Stop
conditions).
SERIAL PORT OPERATION
The Serial Clock input (SCL) and bi–directional data port
(SDA) form a 2–wire bi–directional serial port for
programming and interrogating the MC74. The following
conventions are used in this bus architecture:
All transfers take place under control of a host, usually
a CPU or microcontroller, acting as the Master which
provides the clock signal for all transfers. The MC74
always operates as a Slave. The serial protocol is illustrated
in Figure 1. All data transfers have two phases; all bytes are
transferred MSB first. Accesses are initiated by a start
condition (START), followed by a device address byte and
one or more data bytes. The device address byte includes a
Read/Writeselectionbit. Eachaccessmustbeterminatedby
a Stop Condition (STOP).
A convention called
Acknowledge (ACK) confirms receipt of each byte. Note
thatSDAcanchangeonlyduringperiodswhenSCLisLOW
(SDAchangeswhileSCL isHIGHarereservedforStartand
Stop Conditions).
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4
MC74
Write Byte Format
ADDRESS
ACK
ACK
S
WR
ACK
COMMAND
8 Bits
DATA
P
7 Bits
8 Bits
Slave Address
Command Byte: selects
which register you are
writing to.
Data Byte: data goes
into the register set
by the command byte.
Read Byte Format
ADDRESS WR ACK
S
COMMAND ACK
S
ADDRESS RD ACK
DATA NACK
P
7 Bits
8 Bits
7 Bits
8 Bits
Slave Address
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.
Receive Byte Format
ADDRESS RD ACK
7 Bits
S
DATA NACK
P
8 Bits
Data Byte: reads data from
the register commanded by
the last Read Byte.
S = Start Condition
P = Stop Condition
Shaded = Slave Transmission
Figure 1. SMBus Protocols
Acknowledge (ACK)
Start Condition (START)
The MC74 continuously monitors the SDA and SCL lines
for a start condition (a HIGH to LOW transition of SDA
whileSCLisHIGH)andwillnotresponduntilthiscondition
is met.
Acknowledge (ACK) provides a positive handshake
betweenthehostandtheMC74. ThehostreleasesSDAafter
transmitting eight bits, then generates a ninth clock cycle to
allow the MC74 to pull the SDA line LOW to acknowledge
that it successfully received the previous eight bits of data or
address.
Address Byte
Immediately following the Start Condition, the host must
transmit the address byte to the MC74. The states of A1 and
A0 determine the 7–bit SMBus address for the MC74. The
7–bit address transmitted in the serial bit stream must match
for the MC74 to respond with an Acknowledge (indicating
the MC74 is on the bus and ready to accept data). The eighth
bit in the Address Byte is a Read–Write Bit. This bit is a 1
for a read operation or 0 for a write operation. During the
first phase of any transfer this bit will be set = 0 to indicate
that the command byte is being written.
Data Byte
After a successful ACK of the address byte, the host must
transmit the data byte to be written or clock out the data to
be read. (See the appropriate timing diagrams. ) ACK will
be generated after a successful write of a data byte into the
MC74.
Stop Condition (STOP)
Communications must be terminated by a stop condition
(a LOW to HIGH transition of SDA while SCL is HIGH).
The Stop Condition must be communicated by the
transmitter to the MC74. NOTE: Refer to Timing Diagrams
for serial bus timing.
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5
MC74
SMBUS Write Timing Diagram
A
B
C
D
E F
G
H
I
J
K
L
M
I
I
LOW HIGH
SCL
SDA
t
t
t
t
t
t
SU(STOP) IDLE
SU(START) H(START)
SU–DATA
H–DATA
A = Start Condition
F = Acknowledge Bit Clocked into Master J = Acknowledge Clocked into Master
B = MSB of Address Clocked into Slave G= MSB of Data Clocked into Slave
C = LSB of Address Clocked into Slave H = LSB of Data Clocked into Slave
D = R/W Bit Clocked into Slave
E = Slave Pulls SDA Line Low
K = Acknowledge Clock Pulse
L = Stop Condition, Data Executed by Slave
M= New Start Condition
I = Slave Pulls SDA Line Low
SMBUS Read Timing Diagram
A
B
C
D
E F
G
H
I
J
K
I
I
LOW HIGH
SCL
SDA
t
t
t
t
t
IDLE
SU(START) H(START)
SU–DATA
SU(STOP)
A = Start Condition
E = Slave Pulls SDA Line Low
I = Acknowledge Clock Pulse
J = Stop Condition
K = New Start Condition
B = MSB of Address Clocked into Slave
C = LSB of Address Clocked into Slave
D = R/W Bit Clocked into Slave
F = Acknowledge Bit Clocked into Master
G= MSB of Data Clocked into Master
H = LSB of Data Clocked into Master
Figure 2.
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6
MC74
REGISTER SET and PROGRAMMER’S MODEL
Temperature Register (TEMP), 8–Bits,
READ–ONLY
MC74 Command Set
(SMBus READ_BYTE and WRITE_BYTE)
The binary value (2’s complement format) in this register
represents temperature of the integrated sensor following a
conversion cycle. The registers are automatically updated in
an alternating manner.
Command Byte Description
Command
RTR
Code Function
Temperature Register (TEMP)
00h
01h
Read Temperature (TEMP)
Read/Write Configuration (CONFIG)
D[7]
D[6]
x
D[5]
x
D[4]
x
D[3]
x
D[2]
x
D[1]
x
D[0]
LSB
RWCR
MSB
Configuration Register (CONFIG), 8–BITS,
READ/WRITE
In the temperature data registers, each unit value
represents one degree (Celsius). The value is in
2’s–complement binary format such that a reading of 0000
0000b corresponds to 0°C. Examples of this temperature to
binary value relationship are shown in the following table.
Configuration Register (Config)
D[7]
D[6]
D[5] D[4] D[3] D[2] D[1] D[0]
SHDN
Data Rdy Reserved
Temperature–to–Digital Value Conversion (TEMP)
Bit
POR Function
Type Operation
ACTUAL
REGISTERED
BINARY HEX
D[7]
0
0
0
STANDBY switch
Read/ 1 = standby,
Write 0 = normal
TEMPERATURE
TEMPERATURE
+130.00°C
+127.00°C
+126.50°C
+25.25°C
+0.50°C
+0.25°C
0.00°C
+127°C
+127°C
+127°C
+25°C
+1°C
0°C
0111 1111
0111 1111
0111 1111
0001 1001
0000 0001
0000 0000
0000 0000
0000 0000
0000 0000
1111 1111
1111 1111
1110 0111
1110 0110
1100 1001
1100 1001
1011 1111
D[6]
Data Ready*
Read 1 = ready,
Only
0 = not ready
D[5]—D[0]
Reserved — Al-
ways returns zero
when read.
N/A
N/A
*DATA_RDY bit reset at power–up and SHDN enable (see below).
0°C
-0.25°C
0°C
V
DD
-0.50°C
0°C
-0.75°C
-1°C
-1.00°C
-1°C
DATA_RDY
SHDN
-25.00°C
-25.25°C
-54.75°C
-55.00°C
-65.00°C
-25°C
-25°C
-55°C
-55°C
-65°C
t
t
conv
conv
Figure 3. . DATA_RDY, SHDN Operation Logic
Diagram
Register Set Summary
The MC74’s register set is summarized below. All
registers are 8–bits wide.
Name
Description
POR State
Read Write
TEMP
Internal sensor
temperature (2’s
complement)
0000 0000b*
√
CONFIG CONFIG register
0000 0000b
√
√
*NOTE: The TEMP register immediately will be updated by the
A/D converter after the DATA_RDY bit goes high.
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7
MC74
TAPING FORM
Component Taping Orientation for 5L SOT–23 Devices
USER DIRECTION OF FEED
DEVICE
MARKING
PIN 1
Standard Reel Component Orientation
for TR Suffix Device
(Mark Right Side Up)
Tape & Reel Specifications Table
Package
5L SOT–23
Tape Width (W)
Pitch (P)
Part Per Full Reel
Diameter
8 mm
4 mm
3000
7 inches
MARKING
SOT–23–5
1
2
3
4
+
1
2
MC74
Marking
MC74A5–33SNTR
V5
+
Date Code
3
4
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8
MC74
PACKAGE DIMENSIONS
SOT–23–5
SNTR SUFFIX
PLASTIC PACKAGE
CASE TBD
ISSUE TBD
0.75 (1.90)
REFERENCE
.122 (3.10)
.098 (2.50)
.071 (1.80)
.059 (1.50)
.020 (0.50)
.012 (0.30)
.037 (0.95)
REFERENCE
.122 (3.10)
.106 (2.70)
.057 (1.45)
.035 (0.90)
.010 (0.25)
.004 (0.09)
10° MAX.
.006 (0.15)
.000 (0.00)
.022 (0.55)
.008 (0.20)
NOTE: SOT–23–5 is equivalent to EIAJ–SC74A
Dimensions: inches (mm)
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9
MC74
PACKAGE DIMENSIONS
TO–220
T SUFFIX
PLASTIC PACKAGE
CASE TBD
ISSUE TBD
.185 (4.70)
.165 (4.19)
.410 (10.41)
.390 (9.91)
.113 (2.87)
.103 (2.62)
.055 (1.40)
.045 (1.14)
.156 (3.96)
.146 (3.71)
DIA.
.258 (6.55)
.230 (5.84)
3
– 7.5
.594 (15.09)
.569 (14.45)
5 PLCS.
.037 (0.94)
.027 (0.69)
.560 (14.22)
.518 (13.16)
.020 (0.51)
.012 (0.30)
.072 (1.83)
.062 (1.57)
.115 (2.92)
.095 (2.41)
.273 (6.93)
.263 (6.68)
Dimensions: inches (mm)
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10
MC74
Notes
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11
MC74
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MC74/D
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