MAXIM DS75LV User Manual

SC

SDA

SC

SDA

www.maxim-ic.com

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 DS75LV defaults to 9-bit resolution for software compatibility with the LM75. Communication with the DS75LV is achieved through a simple 2-wire serial interface. Three address pins allow up to eight DS75LV devices to operate on the same 2-wire bus, which greatly simplifies distributed temperaturesensing applications.

The DS75LV thermostat has a dedicated open-drain output (O.S.) and programmable fault tolerance, which allows 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

A block diagram of the DS75LV is shown in Figure 1 and detailed pin descriptions are given in Table 1.

OS

and T

HYST

).

APPLICATIONS

Personal Computers Cellular Base Stations Office Equipment Any Thermally Sensitive System

PIN CONFIGURATION

2

L

O.S.

GND

L

O.S.

GND

3

DS75LVS—SO (150 mils)

2 3

DS75LVU—μSOP/μMAX

DS75L

VDD A

7

0

A

6

1

A

2

V

DD

7 6

A

0

A

1

A

2

DS75LV

Digital Thermometer and Thermostat

FEATURES

 Operating Range from 1.7V to 3.7V  Temperature Measurements Require No

External Components

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

(-67°F to +257°F)

 ±2°C Accuracy Over a -25°C to +100°C Range  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 Read/Write Occurs Through a 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

DS75LVS+ -55°C to +125°C

DS75LVS+T&R -55°C to +125°C

DS75LVU+ -55°C to +12 5°C

DS75LVU+T&R -55°C to +12 5°C

Ordering Information continued at the end of the data sheet.

DS75LV (150-mil) 8-SO DS75LV (150-mil) 8-SO, 2500 Piece Tape-and-Reel DS75LV 8-µSOP (µMAX) DS75LV 8-µSOP (µMAX), 3000 Piece Tapeand-Reel

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DS75LV: Digital Thermometer and Thermostat

ABSOLUTE MAXIMUM RATINGS*

Voltage on VDD, Relative to Ground -0.3V to +4.0V Voltage 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 260°C for 10 seconds

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 DS75LV 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 DS75LV is not exposed to environmental stresses, such as burn-in, that some industrial applications require. For specific reliability information on this product, please contact the factory in Dallas at (972) 371-4448.

DC ELECTRICAL CHARACTERISTICS

(-55°C to +125°C; 1.7V ≤ VDD ≤ 3.7V.)

PARAMETER SYMBOL CONDITIONS MIN MAX UNITS

Supply Voltage VDD (Note 10) 1.7 3.7 V Thermometer Error

(Note 2)

T

ERR

-25 to +100

-55 to +125 Input Logic High VIH (Note 1) 0.7 × VDD 5.5 V Input Logic Low VIL (Note 1) -0.5 0.3 × VDD V

V

OL1

SDA Output Logic Low Voltage (Note 1)

V

OL2

O.S. Saturation Voltage VOL Input current each I/O pin 0.4 < V

I/O Capacitance C Standby Current I

Active Current (Notes 3, 4)

I/O

DD1

I

DD

3mA sink current 0 0.4

6mA sink current 0 0.6 4mA sink current

(Notes 1, 2)

< 0.9 VDD -10 +10

I/O

0.8 V

10 pF (Notes 3, 4) 2

Active Temp Conversions

1000

Communication only 100

AC ELECTRICAL CHARACTERISTICS

(-55°C to +125°C; 1.7V ≤ V

PARAMETER SYMBOL CONDITION MIN TYP MAX UNITS

Resolution

≤ 3.7V.)

DD

9 12 bits

± 2.0 ± 3.0

°C

V

μA

μA μA

9-bit conversions 25

Temperature Conversion Time

t

CONVT

10-bit conversions 50

11-bit conversions 100

12-bit conversions 200

SCL Frequency f Bus Free Time Between a

STOP and START Condition START and Repeated START Hold Time from

400 KHz

SCL

t

(Note 5)

BUF

t

HD:STA

(Notes 5, 6)

1.3

600

ns

2 of 13

ms

μs

DS75LV: Digital Thermometer and Thermostat

Falling SCL Low Period of SCL t High Period of SCL t Repeated START Condition Setup Time to Rising SCL Data-Out Hold Time from Falling SCL Data-In Setup Time to Rising SCL Rise Time of SDA and SCL (Receive) Fall Time of SDA and SCL (Receive) Spike Suppression Filter Time (Deglitch Filter) STOP Setup Time to Rising SCL Capacitive Load for Each Bus Line

(Note 5) 1.3

LOW

(Note 5) 0.6

HIGH

t

SU:STA

t

HD:DAT

t

SU:DAT

t

R

t

F

t

SS

t

SU:STO

C

B

(Note 5) 600 ns (Notes 5, 8) (Note 5)

0

100

(Notes 5, 7) 20 + 0.1CB

0.9 ns

300

(Notes 5, 7) 20 + 0.1CB 300 ns

0 50 ns

(Note 5) 600 ns

400 pF

μs μs

μs

ns

Input Capacitance CI 5 pF Serial Interface Reset Time t

SDA time low (Note 9) 75 325 ms

TIMEOUT

Note 1: All voltages are referenced to ground. Note 2:

Note 3: I Note 4: Note 5: See Timing Diagram in Figure 2. All timing is referenced to 0.9 x V Note 6: After this period, the first clock pulse is generated. Note 7: For example, if C Note 8: The DS75LV provides an internal hold time of at least 75ns on the SDA signal to bridge the undefined region of SCL's falling edge. Note 9: This time-out applies only when the DS75LV is holding SDA low. Other devices can hold SDA low indefinitely and the DS75LV will

Note 10:

Table 1. Detailed Pin Description

PIN SYMBOL PIN DESCRIPTION

Internal heating caused by O.S. loading will cause the DS75LV to read approximately 0.5°C higher if O.S. is sinking the max rated current.

specified with O.S. pin open.

DD

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

I

DD

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

B

not reset. The DS75LV has a maximum operating voltage of 3.7V. Contact Dallas Semiconductor for information on the availability of a 3.7V to

5.5V version of the DS75LV.

and 0.1 x VDD.

DD

1 SDA Data Input/Output. For 2-wire serial communication port. Open-drain. 2 SCL Clock Input. 2-wire serial communication port. 3 O.S. Thermostat Output. Open-drain. 4 GND 5 A2 6 A1 7 A0

Ground Address Input Address Input Address Input

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

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Figure 1. DS75LV Functional Block Diagram

GIS

S

GIS

ODU

C

A

0

A

CO

PRECISION

REFEREN

E

OVERSAMPLING

M

LATOR

VDD

SCL

SD

1 2

ADDRESS

AND

I/O CONTROL

CONFIGURATION

RE

TEMPERATURE

RE

TER

TOS AND T

RE

TER

HYST

GND

Figure 2. Timing Diagram

DS75LV: Digital Thermometer and Thermostat

DIGITAL

IMATOR

DE

O.S.

THERMOSTAT

MPARATOR

RP

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