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

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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

GND

SDA

VDD

GND

SCLK

Note: The TO-220 tab is connected

to pin 3 (GND)

 2002 Microchip Technology Inc. DS21462C-page 1

Temperature

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)

† 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

) .............. -65°C to +150°C

STG

)................................ +150°C

DC CHARACTERISTICS

Electrical Specifications: Unless otherwise noted, V

= 5.0V for TC74AX-5.0VXX, -40°C ≤ TA ≤ 125°C. Note 5

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-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

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

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.

= 3.3V for TC74AX-3.3VXX and

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

+2.0 +3.0

— — 0.2 x V

— —

0.4

0.6

—

°C +25°C <T

VVIOL = 3 mA

< +85°C

0°C < T

-40°C < T

< +125°C

< 0°C

= 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.

varies from the nominal value, accuracy will degrade 1°C/V

DS21462C-page 2  2002 Microchip Technology Inc.

TC74

DC CHARACTERISTICS (CONTINUED)

Electrical Specifications: Unless otherwise noted, V

= 5.0V for TC74AX-5.0VXX, -40°C ≤ TA ≤ 125°C. Note 5

Parameters Sym Min Typ Max Units Conditions

SMBus/I2C Rise Time SMBus/I

C Fall Time

START Condition Setup Time

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)

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

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.

= 3.3V for TC74AX-3.3VXX and

— —

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.

varies from the nominal value, accuracy will degrade 1°C/V

(Rising Edge)

POR

 2002 Microchip Technology Inc. DS21462C-page 3

TC74

SMBUS Read Timing Diagram

LOW

HIGH

SCLK

SDA

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

LOWtHIGH

SCLK

SDA

SU(START)tH(START)

CDEFG H

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

SU-DATA

H-DATA

SU(STO P)tIDLE

I = Acknowledge Clock Pulse J = Stop Condition K = New Start Condition

SU(STOP)tIDLE

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

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/

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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