Datasheet

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AVAILABLE

Functional Diagrams

Pin Configurations appear at end of data sheet.

Functional Diagrams continued at end of data sheet.

UCSP is a trademark of Maxim Integrated Products, Inc.

For pricing, delivery, and

ordering information, please contact Maxim Direct

at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.

FEATURES

§ Temperature measurements require no

external components

§ Measures temperatures from -55°C to +125°C

in 0.5°C increments. Fahrenheit equivalent is

-67°F to 257°F in 0.9°F increments

§ Temperature is read as a 9-bit value (2-byte

transfer)

§ Wide power supply range (2.7V to 5.5V)

§ Converts temperature to digital word in less

than 1 second

§ Thermostatic settings are user definable and

nonvolatile

§ Data is read from/written via a 2-wire serial

interface (open drain I/O lines)

§ Applications include thermostatic controls,

industrial systems, consumer products,

thermometers, or any thermal sensitive

system

§ 8-pin DIP or SO package (150mil and

208mil)

PIN ASSIGNMENT

PIN DESCRIPTION

SDA - 2-Wire Serial Data Input/Output

SCL - 2-Wire Serial Clock

GND - Ground

OUT

- Thermostat Output Signal

A0 - Chip Address Input

A1 - Chip Address Input

A2 - Chip Address Input

- Power Supply Voltage

DESCRIPTION

The DS1621 Digital Thermometer and Thermostat provides 9-bit temperature readings, which indicate

the temperature of the device. The thermal alarm output, T

OUT

, is active when the temperature of the

device exceeds a user-defined temperature TH. The output remains active until the temperature drops

below user defined temperature TL, allowing for any hysteresis necessary.

User-defined temperature settings are stored in nonvolatile memory so parts may be programmed prior to

insertion in a system. Temperature settings and temperature readings are all communicated to/from the

DS1621 over a simple 2-wire serial interface.

DS1621

Digital Thermometer and Thermostat

OUT

GND

DS1621S 8-PIN SO (150mil)

DS1621V 8-PIN SO (208mil)

SCL

OUT

GND

DS1621 8-PIN DIP (300mil)

SCL

090905

Summary of content (16 pages)

PAGE 1
LE AVAILAB DS1621 Digital Thermometer and Thermostat FEATURES § § § § § § § § § PIN ASSIGNMENT Temperature measurements require no external components Measures temperatures from -55°C to +125°C in 0.5°C increments. Fahrenheit equivalent is -67°F to 257°F in 0.9°F increments Temperature is read as a 9-bit value (2-byte transfer) Wide power supply range (2.7V to 5.
PAGE 2
DS1621 ORDERING INFORMATION ORDERING NUMBER DS1621 DS1621+ DS1621S DS1621S+ DS1621S/T&R DS1621S+T&R DS1621V DS1621V+ DS1621V/T&R DS1621V+T&R PACKAGE MARKING DS1621 DS1621 (See Note) DS1621 DS1621 (See Note) DS1621 DS1621 (See Note) DS1621V DS1621V (See Note) DS1621V DS1621V (See Note) DESCRIPTION DS1621 in 300 mil DIP DS1621 in Lead-Free 300 mil DIP DS1621 in 150 mil SOIC DS1621 in Lead-Free 150 mil SOIC DS1621 in 150 mil SO, 2500 Piece Tape-and-Reel DS1621 in Lead-Free 150 mil SO, 2500 Piece Tape-and-Re
PAGE 3
DS1621 Figure 1.
PAGE 4
DS1621 Table 2. TEMPERATURE/DATA RELATIONSHIPS TEMPERATURE DIGITAL OUTPUT (Binary) 01111101 00000000 00011001 00000000 00000000 10000000 00000000 00000000 11111111 10000000 11100111 00000000 11001001 00000000 +125°C +25°C +½°C +0°C -½°C -25°C -55°C DIGITAL OUTPUT (Hex) 7D00h 1900h 0080h 0000h FF80h E700h C900h Since data is transmitted over the 2-wire bus MSB first, temperature data may be written to/read from the DS1621 as either a single byte (with temperature resolution of 1°C) or as two bytes.
PAGE 5
DS1621 In one-shot mode, the DS1621 performs a single temperature conversion when a Start Convert T command is issued. When the conversion is complete, the device enters a low-power idle state and remains in that state until a single temperature conversion is again initiated by a Start Convert T command. Thermostat Control In its operating mode, the DS1621 functions as a thermostat with programmable hysteresis as shown in Figure 3.
PAGE 6
DS1621 TLF = Temperature Low Flag. This bit will be set to “1” when the temperature is less than or equal to the value of TL. It will remain “1” until reset by writing “0” into this location or removing power from the device. This feature provides a method of determining if the DS1621 has ever been subjected to temperatures below TL while power has been applied. NVB = Nonvolatile Memory Busy flag. “1” = Write to an E2 memory cell in progress, “0” = nonvolatile memory is not busy.
PAGE 7
DS1621 Each data transfer is initiated with a START condition and terminated with a STOP condition. The number of data bytes transferred between START and STOP conditions is not limited and is determined by the master device. The information is transferred byte-wise and each receiver acknowledges with a ninth-bit. Within the bus specifications a regular mode (100kHz clock rate) and a fast mode (400kHz clock rate) are defined. The DS1621 works in both modes.
PAGE 8
DS1621 The DS1621 may operate in the following two modes: 1. Slave receiver mode: Serial data and clock are received through SDA and SCL. After each byte is received an acknowledge bit is transmitted. START and STOP conditions are recognized as the beginning and end of a serial transfer. Address recognition is performed by hardware after reception of the slave address and direction bit. 2. Slave transmitter mode: The first byte is received and handled as in the slave receiver mode.
PAGE 9
DS1621 Figure 5.
PAGE 10
DS1621 COMMAND SET Data and control information is read from and written to the DS1621 in the format shown in Figure 5. To write to the DS1621, the master will issue the slave address of the DS1621 and the R/ W bit will be set to “0”. After receiving an acknowledge, the bus master provides a command protocol. After receiving this protocol, the DS1621 will issue an acknowledge and then the master may send data to the DS1621.
PAGE 11
DS1621 Table 3. DS1621 COMMAND SET 2-WIRE BUS DATA AFTER ISSUING INSTRUCTION DESCRIPTION PROTOCOL PROTOCOL TEMPERATURE CONVERSION COMMANDS Read Temperature Read last converted temperature AAh value from temperature register. Read Counter Reads value of Count_Remain A8h Read Slope Reads value of the A9h Count_Per_C Start Convert T Initiates temperature EEh idle conversion. Stop Convert T Halts temperature conversion.
PAGE 12
DS1621 MEMORY FUNCTION EXAMPLE Example: Bus master sets up DS1621 for continuous conversion and thermostatic function.
PAGE 13
DS1621 ABSOLUTE MAXIMUM RATINGS* Voltage on Any Pin Relative to Ground Operating Temperature Range Storage Temperature Range Soldering Temperature -0.5V to +6.0V -55°C to +125°C -55°C to +125°C See IPC/JEDEC J-STD-020A Specification * This is a stress rating 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.
PAGE 14
DS1621 Active Supply Current Standby Supply Current Thermostat Output (TOUT) Output Voltage ICC Temperature Conversion -55°C to +85°C Temperature Conversion +85°C to +125°C E2 Write Communication Only 1000 1250 1 mA Source 4 mA Sink 3, 4 1 µA 3, 4 0.4 V V 400 110 ISTBY VOH VOL µA 2.
PAGE 15
DS1621 AC ELECTRICAL CHARACTERISTICS PARAMETER Temperature Conversion Time NV Write Cycle Time SCL Clock Frequency Bus Free Time Between a STOP and START Condition Hold Time (Repeated) START Condition Low Period of SCL Clock High Period of SCL Clock Setup Time for a Repeated START Condition Data Hold Time Data Setup Time (-55°C to +125°C; VDD = 2.7V to 5.5V) SYMBOL TTC CONDITION tWR 0°C to 70°C fSCL Fast Mode Standard Mode Fast Mode Standard Mode 0 0 1.3 4.7 tHD:STA Fast Mode Standard Mode 0.
PAGE 16
DS1621 NOTES: 1. All voltages are referenced to ground. 2. I/O pins of fast mode devices must not obstruct the SDA and SCL lines if VDD is switched off. 3. ICC specified with TOUT pin open. 4. ICC specified with VCC at 5.0V and SDA, SCL = 5.0V, 0°C to 70°C. 5. After this period, the first clock pulse is generated. 6.