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041607

GENERAL DESCRIPTION

The DS620 digital thermometer and thermostat

provides low-voltage (1.7V ≤ V

≤ 3.5V) temperature

measurements with ±0.5°C accuracy from 0°C to

+70°C and an operating temperature range of -55°C

to +125°C. The DS620 communicates over a 2-wire

digital interface. For distributed-sensing applications,

it is multidroppable with three address pins that allow

up to eight DS620s to operate on a single bus.

The DS620 has thermostat functionality with user-

defined thresholds stored in EEPROM registers, and

it can be configured for standalone thermostat

operation. The programmable output (PO) pin serves

as the thermostat output, and this pin can also be

configured to function as an active-low control for

peripheral devices.

APPLICATIONS

Portable Applications

Low-Voltage Temperature-Sensitive Applications

Computers/Servers

Test Equipment

Medical Instruments

Industrial Applications

TYPICAL OPERATING CIRCUIT

FEATURES

 Low-Voltage Operation: 1.7V to 3.5V

 ±0.5°C Accuracy from 0°C to +70°C

 Operating Temperature Range: -55°C to +125°C

(-67°F to +257°F)

 Temperature Measurements Require No

External Components

 Resolution is User-Selectable to 10-, 11-, 12-, or

13-Bits (0.5°C, 0.25°C, 0.125°C, and 0.0625°C

LSb Weight, Respectively)

 Multidroppable

 Fast (200ms max) Temperature-to-Digital

Conversion Time

 Thermostatic Settings are User-Definable and

Nonvolatile

 Standalone Thermostat Capability

 Data is Read/Written Through a 2-Wire Serial

Interface

 Package: 8-Pin μSOP

ORDERING INFORMATION

PART TEMP RANGE PIN-PACKAGE

DS620U -55°C to +125°C

8 µSOP,

Exposed Pad

DS620U/T&R -55°C to +125°C

8 µSOP

Exposed Pad

Tape-and-Reel

PIN CONFIGURATION

DS620

Low-Voltage, ±0.5°C Accuracy

Digital Thermometer and Thermostat

www.maxim-ic.com

VDD

SDA

SCL

GND

1.7V to 3.5V

HOST

SDA

SCL

1.7V to 3.5V

Thermostat

DS620

PAD

8-Pin

μSOP Package

Exposed Pad

SCL

GND

VDD

Summary of content (15 pages)

PAGE 1
DS620 Low-Voltage, ±0.5°C Accuracy Digital Thermometer and Thermostat www.maxim-ic.com GENERAL DESCRIPTION FEATURES The DS620 digital thermometer and thermostat provides low-voltage (1.7V ≤ VDD ≤ 3.5V) temperature measurements with ±0.5°C accuracy from 0°C to +70°C and an operating temperature range of -55°C to +125°C. The DS620 communicates over a 2-wire digital interface.
PAGE 2
DS620 Digital Thermometer and Thermostat PIN DESCRIPTION PIN NAME 1 2 3 4 5 6 7 8 SDA SCL PO GND A2 A1 A0 VDD PAD FUNCTION Data Input/Output Pin for serial communication. Open drain. (No diode connection to VDD). Clock Input Pin for 2-wire serial communication. Programmable Output Pin. Open drain. (No diode connection to VDD). Ground Pin. Address Input Pin. Address Input Pin. Also serves as an input to trigger one-shot conversions during standalone use. Address Input Pin. Supply Voltage Pin. +1.
PAGE 3
DS620 Digital Thermometer and Thermostat ABSOLUTE MAXIMUM RATINGS Voltage Range on Any Pin, Relative to Ground Operating Temperature Range Storage Temperature Range Soldering Temperature ESD rating on all pins -0.5V to +4.5V -55°C to +125°C -55°C to +125°C See IPC/JEDEC J-STD-020A Specification 4KV HBM Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device.
PAGE 4
DS620 Digital Thermometer and Thermostat AC ELECTRICAL CHARACTERISTICS EEPROM AC Electrical Characteristics PARAMETER SYMBOL CONDITIONS TWR -40°C to +85°C -40°C ≤ TA ≤ +85°C (Note 1) TA = +25°C (Note 1) -40°C to +125°C (Note 2) 10k 20k 40k 10 80k CONDITIONS MIN TYP EEPROM Write Cycle Time EEPROM Writes EEPROM Data Retention NEEWR tEEDR MIN TYP MAX UNITS 10 ms writes years 2-Wire AC Electrical Characteristics PARAMETER SCL Frequency Bus Free Time Between a STOP and START Condition START
PAGE 5
DS620 Digital Thermometer and Thermostat Figure 2. Timing Diagram Table 1. Register Summary Parameter Information TH and TL Registers Size: 2-Bytes Note that the 3 LSbs are always “don’t cares” for writes (i.e., they are not saved) and always read out as 0s. Configuration Register Size: 2-Bytes Temperature Register Size: 2-Bytes EEPROM Factory State: TH = 15ºC (0000 0111 1000 0000) [0780h] TL = 10ºC (0000 0101 0000 0000) [0500h] SRAM and EEPROM.
PAGE 6
DS620 Digital Thermometer and Thermostat the device enters a low-power standby state and remains in that state until a temperature conversion is again initiated by a Start Convert command. The R0 and R1 bits in the configuration register allow the user to set the conversion resolution to be 10, 11, 12, or 13 bits (0.5°C, 0.25°C, 0.125°C, and 0.0625°C LSb weight, respectively) as shown in Table 6. The default resolution at power-up is 13-bits.
PAGE 7
DS620 Digital Thermometer and Thermostat THERMOSTAT OPERATION The PO pin on the DS620 operates as the thermostat output when it is configured as PO-HIGH or PO-LOW through the P01 and P02 bits of the configuration register. In both of these configurations, PO is updated after every temperature conversion or write to the temperature register, and remains at the updated value until the next conversion or write completes.
PAGE 8
DS620 Digital Thermometer and Thermostat PO PIN The PO pin is a user-programmable open-drain output, which is configured through the PO1 and PO2 bits in the configuration register. PO can operate as a thermostat output (PO-HIGH or PO-LOW), or it can be forced low for control of peripheral devices. When PO is configured as PO-HIGH or PO-LOW, this pin operates as described in the Thermostat Operation section. This pin can be reconfigured at anytime to switch between functions.
PAGE 9
DS620 Digital Thermometer and Thermostat Figure 5. Configuration Register Address ACh MS Byte bit 15 bit 14 bit 13 bit 12 bit 11 bit 10 bit 9 bit 8 DONE NVB THF TLF R1* R0* AUTOC* 1SHOT* Address ADh LS Byte bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 PO2 PO1* A2 A1 A0 M* M* M* * Stored in EEPROM Table 5.
PAGE 10
DS620 Digital Thermometer and Thermostat PO2 PO1* * A2 A1 A0 M* Read/Write Read/Write Read Only Read Only Read Only Read/Write conversions can be performed. See Writing the 1SHOT Bit Command Sequence section for writing more information on writing the 1SHOT bit. At power-up, PO2 = 1. PO2 = 0 forces the PO pin low (see Table 3) PO2 = 1 configures PO as the thermostat output (PO-HIGH or PO-LOW, as determined by PO1).
PAGE 11
DS620 Digital Thermometer and Thermostat is acting as a receiver, it uses a NACK instead of an ACK after the last data byte to indicate that it is finished receiving data. The master indicates a NACK by leaving the SDA line high during the ACK clock cycle. Slave Address: Every slave device on the bus has a unique 7-bit address that allows the master to access that device. The DS620’s 7-bit bus address is 1 0 0 1 A2 A1 A0, where A2, A1, and A0 are user-selectable via the corresponding input pins.
PAGE 12
DS620 Digital Thermometer and Thermostat the DS620 commands. See Writing to the DS620 or Reading from the DS620 for more information on reading from and writing to the DS620. WRITING TO THE DS620 The master can write data to the DS620 by issuing an address byte following the control byte. The R/W bit in the control byte must be a 0 (write).
PAGE 13
DS620 Digital Thermometer and Thermostat COPYING TO EEPROM COMMAND SEQUENCE Data is written to DS620 and then copied from SRAM to EEPROM RX RX TX DATA (MSB FIRST) START ACK TX RX A4h RX TX ACK TX RX RX TX ACK TX RX RX TX ACK TX RX RX TX ACK TX RX RX TX TX RX TX RX RX TX ACK START ACK TX RX ACh RX TX ACK TX RX xxxxxxx0b RX TX TX RX TX RX RX TX ACK START ACK TX RX 51h RX TX ACK TX TX RX RX R
PAGE 14
DS620 Digital Thermometer and Thermostat RX TX ACK TX RX xxxxxxx1b TX TX RX RX RX TX START ACK TX RX 48h RX TX TX RX TX RX RX TX ACK START ACK TX RX 22h RX TX ACK TX RX STOP DS620 generates acknowledge. Bus master writes to the configuration register putting the DS620 back in 1SHOT mode: 1SHOT = 1. Bus master generates a repeated start condition. Bus master sends DS620 address, R/W = 0. DS620 generates acknowledge.
PAGE 15
DS620 Digital Thermometer and Thermostat RX TX TX RX TX RX RX TX ACK START ACK TX RX 22h RX TX ACK TX RX STOP DS620 generates acknowledge. Bus master generates a repeated start condition. Bus master sends DS620 address, R/W = 0. DS620 generates acknowledge. Bus master sends STOP CONVERT command to stop the DS620 from continuously converting temperature.