DS620 Digital Thermometer and Thermostat

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PO PIN

The PO pin is a user-programmable open-drain output, which is configured through the PO1 and PO2 bits in the

Thermostat Operation section. This pin can be reconfigured at anytime to switch between functions. Table 3

defines the various configuration options for this pin.

Table 3. PO Configuration

Function

PO2

PO1

Thermostat Output (PO-high)

1

1

Thermostat Output (PO-low)

1

0

Force PO Low

0

X

EEPROM REGISTERS AND MEMORY MAP

The DS620 has a 14-byte linear address space with registers for temperature, thermostat thresholds, and control

as well as four bytes of user EEPROM for general use. All address space is shadowed by RAM. The DS620

Memory Map is shown in Table 4.

See the Writing to the DS620 and the Reading from the DS620 sections for details in writing to and reading from

the DS620 EEPROM registers and memory map.

Table 4. Memory Map

Address (hex)

Description

A0

TH MSB

A1

TH LSB

A2

TL MSB

A3

TL LSB

A4

User

A5

User

A6

User

A7

User

A8

Undefined

A9

Undefined

AA

Temperature MSB

AB

Temperature LSB

AC

Configuration MSB

AD

Configuration LSB

CONFIGURATION REGISTER

The configuration register allows the user to program various DS620 options such as conversion resolution,

operating mode, and thermostat capability. It also provides information to the user about conversion status,

EEPROM activity, device address, and thermostat activity. The configuration register is arranged as shown in

Figure 5 and detailed descriptions of each bit are provided in Table 5. It is located in address spaces ACh (MSB)

and ADh (LSB) in the DS620 memory. Note that the R0, R1, AUTOC, 1SHOT, and PO1 bits are stored in

EEPROM so they can be programmed prior to installation if desired. All other configuration bits are SRAM and

power up in the state shown in Table 5.