Philips LM75A Operation Manual

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LM75A

Digital temperature sensor and thermal Watchdog

Product data sheet Supersedes data of 2001 Jul 16

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2004 Oct 05

Philips Semiconductors Product data sheet

TYPE NUMBER

Topside mark

LM75ADigital temperature sensor and thermal Watchdog

GENERAL DESCRIPTION

The LM75A is a temperature-to-digital converter using an on-chip band-gap temperature sensor and Sigma-delta A-to-D conversion technique. The device is also a thermal detector providing an over-temp detection output. The LM75A contains a number of data registers: Configuration register (Conf) to store the device settings such as device operation mode, OS operation mode, OS polarity and OS fault queue as described in the functional description section; temperature register (Temp) to store the digital temp reading, and set-point registers (Tos & Thyst) to store programmable overtemp shutdown and hysteresis limits, that can be communicated by a controller via the 2-wire serial I also includes an open-drain output (OS) which becomes active when the temperature exceeds the programmed limits. There are three selectable logic address pins so that eight devices can be connected on the same bus without address conflict.

The LM75A can be configured for different operation conditions. It can be set in normal mode to periodically monitor the ambient temperature, or in shutdown mode to minimize power consumption. The OS output operates in either of two selectable modes: OS comparator mode and OS interrupt mode. Its active state can be selected as either HIGH or LOW. The fault queue that defines the number of consecutive faults in order to activate the OS output is programmable as well as the set-point limits.

The temperature register always stores an 11-bit 2’s complement data giving a temperature resolution of 0.125 °C. This high temperature resolution is particularly useful in applications of measuring precisely the thermal drift or runaway.

The device is powered-up in normal operation mode with the OS in comparator mode, temperature threshold of 80 °C and hysteresis of 75 °C, so that it can be used as a stand-alone thermostat with those pre-defined temperature set points.

C-bus interface. The device

FEA TURES

•Pin-for-pin replacement for industry standard LM75 and offers

improved temperature resolution of 0.125 °C and specification of a single part over power supply range from 2.8 V to 5.5 V .

•Small 8-pin package types: SO8 and TSSOP8

•I

C-bus interface with up to 8 devices on the same bus

•Power supply range from 2.8 V to 5.5 V

•Temperatures range from –55 °C to +125 °C

•11-bit ADC that offers a temperature resolution of 0.125 °C

•Temperature accuracy of:

±2 °C from –25 °C to +100 °C ±3 °C from –55 °C to +125 °C

•Programmable temperature threshold and hysteresis set points

•Supply current of 3.5 µA in shut-down mode for power

conservation

•Stand-alone operation as thermostat at power-up.

•ESD protection exceeds 2000 V HBM per JESD22-A114,

200 V MM per JESD22-A115 and 1000 V CDM per JESD22-C101

•Latch-up testing is done to JESDEC Standard JESD78 which

exceeds 100 mA

APPLICATIONS

•System thermal management

•Personal computers

•Electronics equipment

•Industrial controllers.

ORDERING INFORMATION

= –55 °C to +125 °C

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PACKAGE NAME DESCRIPTION VERSION

LM75AD LM75A SO8 plastic small outline package; 8 leads; body width 3.9 mm SOT96-1 LM75ADP LM75A TSSOP8 plastic thin shrink small outline package; 8 leads; body width 3 mm SOT505-1

WATCHDOG is a trademark of National Semiconductor Corporation.

2004 Oct 05

Philips Semiconductors Product data sheet

LM75ADigital temperature sensor and thermal Watchdog

PINNING Pin configuration

1 2

SCL

GND

SL01388

Figure 1. SO8 and TSSOP8 pin configurations.

SIMPLIFIED BLOCK DIAGRAM

LM75A

BIAS

REFERENCE

BAND–GAP

TEMP

SENSOR

OSC

Pin description

PIN SYMBOL DESCRIPTION

8SDA

11–BIT

SIGMA–DELTA

A–TO–D

CONVERTER

1 SDA Digital I/O. I2C serial bi-directional data line.

Open Drain. 2 SCL Digital input. I2C serial clock input. 3 OS Overtemp Shutdown output. Open Drain. 4 GND Ground. To be connected to the system

ground. 5 A2 Digital input. User-defined address bit2. 6 A1 Digital input. User-defined address bit1. 7 A0 Digital input. User-defined address bit0.

8 V

POINTER

COUNTER

TIMER

Power supply.

CONFIGURATION

TEMPERATURE

TOS

POWER–ON

RESET

LOGIC CONTROL AND INTERFACE

A2 A1 A0 SCL

Figure 2. Simplified block diagram.

SDA

COMPARA TOR

/ INTERRUPT

GND

THYST

SL01389

2004 Oct 05

Philips Semiconductors Product data sheet

LM75ADigital temperature sensor and thermal Watchdog

TYPICAL APPLICATION

VCC POWER SUPPLY

5 6 7

0.1 µF

SCL

SDA

A2 A1 A0

8 V

GND

10 kΩ

3LM75A

DETECTOR OR

INTERRUPT LINE

SL01390

BUS PULL-UP RESISTORS

I2C-BUS

DIGITAL LOGIC

10 kΩ10 kΩ

Figure 3. Typical application.

ABSOLUTE MAXIMUM RATINGS

SYMBOL

PARAMETER MIN. MAX. UNIT

VCC to GND –0.3 6.0 V Voltage at input pins –0.3 6.0 V Current at input pins –5.0 5.0 mA OS output sink current – 10.0 mA OS output voltage –0.3 6.0 V

ESD

Human Body Model – 2000 V Machine Model – 200 V

stg

Storage temperature range –65 150 °C Junction temperature – 150 °C

NOTE:

1. This is a stress rating only. Functional operation of the device as indicated in the operational section is not applied to this absolute maximum rating. Stresses above those listed in ‘Absolute Maximum Ratings’ may cause permanent damage to the device and exposure to any of these rating conditions for extended periods may affect device reliability .

OPERATING RA TINGS

SYMBOL PARAMETER MIN. MAX. UNIT

amb

2004 Oct 05

Supply voltage 2.8 5.5 V Operating ambient temperature range –55 125 °C

Philips Semiconductors Product data sheet

LM75ADigital temperature sensor and thermal Watchdog

DC ELECTRICAL CHARACTERISTICS

VCC = 2.8 V to 5.5 V, T

SYMBOL

T T

ACC

RES CON

V V

IHYS

IH IL

Temperature accuracy

T emperature resolution 11-bit digital temp data – 0.125 – °C T emperature conversion Normal mode – 100 – ms Supply quiescent current

HIGH-level input voltage Digital pins (SCL, SDA, A2–A0) 0.7 × V LOW-level input voltage Digital pins –0.3 – 0.3 × V Input voltage hysteresis

HIGH–level input current Digital pins; VIN = V LOW-level input current Digital pins; VIN = 0 V –1.0 – 1.0 µA LOW-level output voltage

Output leakage current SDA and OS pins; VOH = V

OSQ OS fault queue Programmable 1 – 6 Conv

Tos Overtemp shutdown Default value – 80 – °C

Thyst Hysteresis Default value – 75 – °C

Input capacitance Digital pins – 20 – pF

NOTE:

1. Typical values are at V

2. Conv: device A-to-D conversion.

= –55 °C to +125 °C unless otherwise noted.

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PARAMETER CONDITIONS MIN. TYP.

= –25 °C to +100 °C –2 – +2 °C

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= –55 °C to +125 °C –3 – +3 °C

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Normal mode: I2C inactive – 100 – µA Normal mode: I2C active – – 1.0 mA Shut–down mode – 3.5 – µA

SCL and SDA pins – 300 – mV A2–A0 pins – 150 – mV

–1.0 – 1.0 µA

SDA and OS pins; IOL = 3 mA – – 0.4 V IOL = 4 mA – – 0.8 V

– – 10 µA

= 3.3 V and T

amb

= 25 °C.

MAX. UNIT

– VCC + 0.3 V

2004 Oct 05

Philips Semiconductors Product data sheet

LM75ADigital temperature sensor and thermal Watchdog

I2C INTERFACE AC CHARACTERISTICS

VCC = 2.8 V to 5.5 V, T

SYMBOL

CLK

HIGH

LOW

HD:STA

SU:DAT

HD;DAT

SU;STO

SCL clock period See timing diagram (Figure 4) 2.5 – – µs SCL HIGH pulse width 0.6 – – µs SCL LOW pulse width 1.3 – – µs Start Hold time 100 – – ns Data set–up time 100 – – ns Data hold time 0 – – ns Stop set-up time 100 – – ns Fall time (SDA and OS outputs) CL = 400 pF; IOL = 3 mA – 250 – ns

= –55 °C to +125 °C unless otherwise noted.

amb

PARAMETER CONDITIONS MIN. TYP. MAX. UNIT

NOTE:

1. These specifications are guaranteed by design and not tested in production.

CLK

HIGH

SCL

HD;STA

SU;DAT

HD;DAT

SDA

LOW

SU;STO

Figure 4. Timing diagram.

SL01391

2004 Oct 05

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