Maxim Integrated Producs DS75LXU+T-R, DS75LX Datasheet

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GENERAL DESCRIPTION

This low-voltage (1.7V to 3.7V) digital thermometer and thermostat provides 9, 10, 11, or 12-bit digital temperature readings over a -55°C to +125°C range with ±2°C accuracy over a -25°C to +100°C range. At power-up, the DS75LX defaults to 9-bit resolution for software compatibility with the LM75. Communication with the DS75LX is achieved through a simple 2-wire serial interface. Three tri-state address pins allow up to 27 DS75LX devices to operate on the same 2-wire bus, which greatly simplifies distributed temperaturesensing applications.

The DS75LX thermostat has a dedicated open-drain output (O.S.) and programmable fault tolerance, which allow the user to define the number of consecutive error conditions that must occur before O.S. is activated. There are two thermostatic operating modes that control thermostat operation based on user-defined trip-points (T

and T

HYST

APPLICATIONS

Any Thermally Sensitive System Cellular Base Stations Telecom Switches and Routers Servers

PIN CONFIGURATIONS

FEATURES

 1.7V to 3.7V Operating Range  Tri-State Address Pins Allow Up to 27 Unique

Bus Addresses

 Temperature Measurements Require No

External Components

 Measures Temperatures from -55°C to +125°C

(-67°F to +257°F)

 ±2°C Accuracy from -25°C to +100°C  Thermometer Resolution Is User-

Configurable from 9 (Default) to 12 Bits (0.5°C to 0.0625°C Resolution)

 9-Bit Conversion Time is 25ms (max)  Thermostatic Settings are User-Definable  Data is Read/Written Through 2-Wire Serial

Interface (SDA and SCL Pins)

 Data Lines Filtered Internally for Noise

Immunity (50ns Deglitch)

 Bus Timeout Feature Prevents Lockup

Problems on 2-Wire Interface

 Multidrop Capability Simplifies Distributed

Temperature-Sensing Applications

 Pin/Software Compatible with the LM75  Available in 8-Pin μSOP (μMAX

) and SO

Packages

ORDERING INFORMATION

PART TEMP RANGE

PIN PACKAGE

DS75LXS+ -55°C to +125°C

8 SO (150 mils)

DS75LXS+T&R -55°C to +125°C

8 SO (150 mils), 2500 Piece

DS75LXU+ -55°C to +125°C

8 µSOP (µMAX)

DS75LXU+T&R -55°C to +125°C

8 µSOP (µMAX), 3000 Piece

+ Denotes lead-free package. T&R denotes tape-and-reel.

Note: A “+” symbol will also be marked on the package near the pin 1 indicator.

µMAX is a registered trademark of Maxim Integrated Products, Inc.

DS75LX

Digital Thermometer and Thermostat

with Extended Addressing

www.maxim-ic.com

SO (150 mils)

VDD A

GND

O.S.

SDA

DS75

SOP/μMAX

GND

O.S.

SDA

DS75

DS75LX: Digital Thermometer and Thermostat with Extended Addressing

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ABSOLUTE MAXIMUM RATINGS

Voltage Range on VDD, Relative to Ground -0.3V to +4.0V Voltage Range on Any Other Pin, Relative to Ground -0.3V to +6.0V Operating Temperature Range -55°C to +125°C Storage Temperature Range -55°C to +125°C Soldering Temperature See IPC/JEDEC J-STD-020

These are stress ratings only and functional operation of the device at these or any other conditions above those indicated in the operation sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability.

The Dallas Semiconductor DS75LX is built to the highest quality standards and manufactured for long-term reliability. All Dallas Semiconductor devices are made using the same quality materials and manufacturing methods. However, the DS75LX is not exposed to environmental stresses, such as burn-in, that some industrial applications require. For specific reliability information on this product, contact the factory in Dallas at (972) 371-

4448.

DC ELECTRICAL CHARACTERISTICS

(1.7V ≤ VDD ≤ 3.7V, TA = -55°C to +125°C.)

PARAMETER SYMBOL CONDITIONS MIN MAX UNITS

Supply Voltage VDD (Note 1) 1.7 3.7 V

-25°C to +100°C

±2.0

Thermometer Error (Note 2)

ERR

-55°C to +125°C

±3.0

°C

Input Logic-High SDA, SCL

(Note 3) 0.7 x VDD V

+ 0.3 V

Input Logic-Low SDA, SCL

VSS - 0.3 0.3 x VDD V

OL1

3mA sink current 0 0.4

SDA Output Logic-Low Voltage (Note 3)

OL2

6mA sink current 0 0.6

O.S. Saturation Voltage VOL

4mA sink current (Notes 2, 3)

0.8 V

Input Current SDA, SCL 0.4 < V

I/O

< 0.9VDD -10 +10 µA

I/O Capacitance C

I/O

10 pF Address Input Sink Current

LAH

A0, A1, or A2 tied to V

(Notes 4, 5)

0.2 3.5 µA

Address Input Source Current

LAL

A0, A1, or A2 tied to GND (Notes 4, 5)

0.2 3.5 µA

Address Voltage High VAH (Note 6) V

- .04 V

Address Voltage Low VAL (Note 6) V

+ .04 V

Standby Current I

DD1

(Notes 4, 5) 13 µA

Active temp conversions 1000 Active Current

(Notes 1, 4, 5)

Communication only 100

µA

AC ELECTRICAL CHARACTERISTICS

(1.7V ≤ VDD ≤ 3.7V, TA = -55°C to +125°C.)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Resolution

9 12 Bits

9-bit conversions 25

10-bit conversions 50

11-bit conversions 100

Temperature Conversion Time

CONVT

12-bit conversions 200

SCL Frequency f

SCL

400 kHz

DS75LX: Digital Thermometer and Thermostat with Extended Addressing

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AC ELECTRICAL CHARACTERISTICS (continued)

(1.7V ≤ VDD ≤ 3.7V, TA = -55°C to +125°C.)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Bus Free Time Between a STOP and START Condition

BUF

(Note 7)

1.3

µs

START and Repeated START Hold Time from Falling SCL

HD:STA

(Notes 7, 8)

600

Low Period of SCL t

LOW

(Note 7) 1.3 µs

High Period of SCL t

HIGH

(Note 7) 0.6 µs Repeated START Condition Setup Time to Rising SCL

SU:STA

(Note 7) 600 ns

Data-Out Hold Time from Falling SCL

HD:DAT

(Notes 7, 9) 0 0.9 µs

Data-In Setup Time to Rising SCL

SU:DAT

(Note 7)

100

Rise Time of SDA and SCL (Receive)

(Notes 7, 10)

20 +

0.1C

300 ns

Fall Time of SDA and SCL (Receive)

(Notes 7, 10)

20 +

0.1CB

300 ns

Spike Suppression Filter Time (Deglitch Filter)

0 50 ns

STOP Setup Time to Rising SCL

SU:STO

(Note 7) 600 ns

Capacitive Load for Each Bus Line

400 pF

Input Capacitance CI 5 pF Serial Interface Reset Time

TIMEOUT

SDA time low (Notes 11, 12)

75 325 ms

Note 1: VDD must be decoupled with a high-quality 0.1µF bypass capacitor. X5R or X7R ceramic surface-mount capacitors are

recommended.

Note 2:

Internal heating caused by O.S. loading causes the DS75LX to read approximately 0.5°C higher if O.S. is sinking the max rated current.

Note 3: All voltages are referenced to ground. Note 4: I

specified with O.S. pin open and A0–A2 pins grounded.

Note 5:

and address leakage specified with VDD at 3.0V and SDA, SCL = 3.0V at 0°C to +70°C.

Note 6: Address pins A0, A1, A2 are directly connected to V

, VSS, or floating with less than 50pF capacitive load.

Note 7: See the timing diagram (Figure 1). All timing is referenced to 0.9 x V

and 0.1 x VDD.

Note 8: After this period, the first clock pulse is generated. Note 9: The DS75LX provides an internal hold time of at least 75ns on the SDA signal to bridge the undefined region of SCL's falling

edge.

Note 10: For example, if C

= 300pF, then tR[min] = tF[min] = 50ns.

Note 11: This timeout applies only when the DS75LX is holding SDA low. Other devices can hold SDA low indefinitely and the DS75LX

will not reset.

Note 12: The DS75LX is available with timeout feature disabled upon special order. Contact Factory.

PIN DESCRIPTION

PIN NAME FUNCTION

1 SDA Data Input/Output for 2-Wire Serial Communication Port (Open Drain) 2 SCL Clock Input for 2-Wire Serial Communication Port 3 O.S. Thermostat Output Open Drain 4 GND Ground 5 A2 Address Input 6 A1 Address Input 7 A0 Address Input

8 VDD

Supply Voltage. +1.7V to +3.7V supply pin. V

must have an external bypass

capacitor to GND. 0.1µF X5R or X7R ceramic SMT caps recommended.

DS75LX: Digital Thermometer and Thermostat with Extended Addressing

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BLOCK DIAGRAM

Figure 1. Timing Diagram

TOS AND T

HYST

GIS

TER

CONFIGURATION

GIS

TER

TEMPERATURE

GIS

TER

OVERSAMPLING

ODU

LATOR

PRECISION

REFEREN

DIGITAL

IMATOR

ADDRESS

AND

I/O CONTROL

SCL

VDD

GND

THERMOSTAT

MPARATOR

O.S.

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