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TC74A2-5.0VCT
Schematic [ru]
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Microchip TC74A0-3.3VCT, TC74A0-5.0VCT, TC74A1-3.3VCT, TC74A1-5.0VCT, TC74A2-3.3VCT Schematic [ru]

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M
Tiny Serial Digital Thermal Sensor
TC74
Features
• Digital Temperature Sensing in SOT-23-5 or TO-220 Packages
• Outputs Temperature as an 8-Bit Digital Word
• Simple SMBus/I
• Solid-State Temperature Sensing:
- ±2°C (max.) Accuracy from +25°C to +85°C
- ±3°C (max.) Accuracy from 0°C to +125°C
• Supply Voltage of 2.7V to 5.5V
•Low Power:
- 200 µA (typ.) Operating Current
- 5 µA (typ.) Standby Mode Current
C™ Serial Port Interface
Applications
• Thermal Protection for Hard Disk Drives and other PC Peripherals
• PC Card Devices for Notebook Computers
• Low Cost Thermostat Controls
• Power Supplies
• Thermistor Replacement
Package Types
TO-220 SOT-23
TC74
12345
SDA
5 4
TC74
SCLK
General Description
The TC74 is a serially accessible, digital temperature sensor particularly suited for low cost and small form­factor applications. Temperature data is converted from the onboard thermal sensing element and made available as an 8-bit digital word.
Communication with the TC74 is accomplished via a 2­wire SMBus/I can be used to implement multi-drop/multi-zone monitoring. The SHDN bit in the CONFIG register can be used to activate the low power Standby mode.
Temperature resolution is 1°C. Conversion rate is a nominal 8 samples/sec. During normal operation, the quiescent current is 200 µA (typ). During standby operation, the quiescent current is 5 µA (typ).
Small size, low installed cost and ease of use make the TC74 an ideal choice for implementing thermal management in a variety of systems.
C compatible serial port. This bus also
Functional Block Diagram
Internal Sensor
(Diode)
∆Σ
Modulator
Serial Port
Interface
Control
Logic
SDA
SCLK
12
GND
NC
SDA
VDD
GND
SCLK
Note: The TO-220 tab is connected
to pin 3 (GND)
2002 Microchip Technology Inc. DS21462C-page 1
NC
3
V
DD
Temperature
Register
TC74

1.0 ELECTRICAL CHARACTERISTICS

1.1 Absolute Maximum Ratings†

Supply Voltage (VDD) ............................................ +6V
Voltage On Any Pin ....... (GND – 0.3V) to (V
+ 0.3V)
DD
† Notice: Stresses above those listed under "Maxi­mum Ratings" may cause permanent damage to the device. This is a stress rating only and functional oper­ation of the device at those or any other conditions above those indicated in the operation listings of this specification is not implied. Exposure to maximum rat­ing conditions for extended periods may affect device reliability.
Current On Any Pin .......................................... ±50 mA
Operating Temperature (T
Storage Temperature (T
Junction Temperature (T
) ........ -40°C ≤ TA ≤ +125°C
A
) .............. -65°C to +150°C
STG
)................................ +150°C
J
DC CHARACTERISTICS
Electrical Specifications: Unless otherwise noted, V
V
= 5.0V for TC74AX-5.0VXX, -40°C ≤ TA ≤ 125°C. Note 5
DD
Parameters Sym Min Typ Max Units Conditions
Power Supply
Power-on Reset Threshold V
Supply Voltage V
Operating Current I
Standby Supply Current I
POR
DD
DD
DD-STANDBY
Temperature-to-Bits Converter
Temperature Accuracy T
ERR
Conversion Rate CR 4 8 — SPS Note 2
Serial Port Interface
Logic Input High V
Logic Input Low V
SDA Output Low V
Input Capacitance SDA, SCLK C
I/O Leakage I
Serial Port AC Timing (C
SMBus/I
C Clock Frequency f
LOAD
= 80 pF)
Low Clock Period t
High Clock Period t
IH
IL
OL
IN
LEAK
SMB
LOW
HIGH
0.8 x V
Note 1: Operating current is an average value integrated over multiple conversion cycles. Transient current may
exceed this specification.
2: Maximum ensured 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 TC74 will
cause self-heating and temperature drift error.
4: SDA and SCLK must be connected to V 5: V
= 3.3V for TC74AX -3.3 VXX. VDD = 5.0V for TC74AX -5.0 VXX. All part types of the TC74 will operate
DD
properly over the wider power supply range of 2.7V to 5.5V. Each part type is tested and specified for rated accuracy at its nominal supply voltage. As V of V
change.
DD
= 3.3V for TC74AX-3.3VXX and
DD
1.2 — 2.2 V VDD Falling Edge or Rising Edge
2.7 — 5.5 V Note 5
— 200 350 µA VDD = 5.5V, Note 1
— 5.0 10 µA VDD = 3.3V
Serial Port Inactive, Note 4
-2.0
-3.0 —
— —
±2.0
——V
DD
+2.0 +3.0
— — 0.2 x V
— —
— —
0.4
0.6
—
°C +25°C <T
V
DD
VVIOL = 3 mA
< +85°C
0°C < T
-40°C < T
I
OL
A
< +125°C
A
< 0°C
A
= 6 mA, Note 3
—5.0— pF
-1.0 0.1 1.0 µA
10 — 100 kHz
4.7 — — µsec 10% to 10%
4.0 — — µsec 90% to 90%
or GND.
DD
varies from the nominal value, accuracy will degrade 1°C/V
DD
DS21462C-page 2 2002 Microchip Technology Inc.
TC74
DC CHARACTERISTICS (CONTINUED)
Electrical Specifications: Unless otherwise noted, V
V
= 5.0V for TC74AX-5.0VXX, -40°C ≤ TA ≤ 125°C. Note 5
DD
Parameters Sym Min Typ Max Units Conditions
SMBus/I2C Rise Time SMBus/I
C Fall Time
START Condition Setup Time
t
R
t
F
t
SU(START)
(for repeated START Condition)
START Condition Hold Time t
Data In Setup Time t
Data In Hold Time t
STOP Condition Setup Time t
Bus Free Time Prior to New
H(START)
SU-DATA
H-DAT
SU(STOP)
t
IDLE
Transition
Power-on Reset Delay t
POR
Note 1: Operating current is an average value integrated over multiple conversion cycles. Transient current may
exceed this specification.
2: Maximum ensured 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 TC74 will
cause self-heating and temperature drift error.
4: SDA and SCLK must be connected to V 5: V
= 3.3V for TC74AX -3.3 VXX. VDD = 5.0V for TC74AX -5.0 VXX. All part types of the TC74 will operate
DD
properly over the wider power supply range of 2.7V to 5.5V. Each part type is tested and specified for rated accuracy at its nominal supply voltage. As V of V
change.
DD
= 3.3V for TC74AX-3.3VXX and
DD
— —
— —
1000
300
nsec nsec
10% to 90% 90% to10%
4.0 — — µsec 90% SCLK to 10% SDA
4.0 — — µsec
1000 — — nsec
1250 — — nsec
4.0 — — µsec
4.7 — — µsec
—500—µsecVDD ≥ V
or GND.
DD
varies from the nominal value, accuracy will degrade 1°C/V
DD
(Rising Edge)
POR
2002 Microchip Technology Inc. DS21462C-page 3
TC74
SMBUS Read Timing Diagram
t
LOW
B
t
HIGH
A
SCLK
SDA
t
SU(START)tH(START)
A = Start Condition B = MSB of Address Clocked into Slave C = LSB of Address Clocked into Slave D = R/W Bit Clocked into Slave
SMBUS Write Timing Diagram
B
t
LOWtHIGH
SCLK
SDA
t
SU(START)tH(START)
A
CDEFG H
t
SU-DATA
E = Slave Pulls SDA Line Low F = Acknowledge Bit Clocked into Master G = MSB of Data Clocked into Master H = LSB of Data Clocked into Master
CDEFG HIJ
t
SU-DATA
t
H-DATA
IJ
t
SU(STO P)tIDLE
I = Acknowledge Clock Pulse J = Stop Condition K = New Start Condition
KL
t
SU(STOP)tIDLE
K
M
A = Start Condition B = MSB of Address Clocked into Slave C = LSB of Address Clocked into Slave D = R/W E = Slave Pulls SDA Line Low
Bit Clocked into Slave
F = Acknowledge Bit Clocked into Master G = MSB of Data Clocked into Slave H = LSB of Data Clocked into Slave I = Slave Pulls SDA Line Low

FIGURE 1-1: Timing Diagrams.

J = Acknowledge Clocked into Master K = Acknowledge Clock Pulse L = Stop Condition, Data Executed by Slave M = New Start Condition
DS21462C-page 4 2002 Microchip Technology Inc.

2.0 PIN DESCRIPTIONS

The descriptions of the pins are listed in Table 2-1.

TABLE 2-1: PIN FUNCTION TABLE

Pin No.
(5-Pin
SOT-23)
1 1 NC None No Internal Connection
2 3 GND Power System Ground
35V
4 4 SCLK Input SMBus/I
5 2 SDA Bidirectional SMBus/I

2.1 Ground (GND)

Input. Ground return for all TC74 functions.

2.2 Power Supply Input (VDD)

Power supply input. See Electrical Specifications.

2.3 SMBus/I2C Serial Clock (SCLK)

Pin No.
(5-Pin TO-220)
Symbol Type Description
DD
Power Power Supply Input
C Serial Clock
C Serial Data
TC74
Input. SMBus/I2C serial clock. Clocks data into and out of the TC74. See System Management Bus Specification, Rev. 1.0, for timing diagrams.

2.4 Serial Data (SDA)

Bidirectional. Serial data is transferred on the SMBus/
I
C in both directions using this pin. See System Management Bus Specification, Rev. 1.0 for timing diagrams.
2002 Microchip Technology Inc. DS21462C-page 5
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