3

TCN75

PRELIMINARY INFORMATION

2-WIRE SERIAL TEMPERATURE

SENSOR AND THERMAL MONITOR

TCN75-04 6/16/97

noted.

Symbol

Parameter

Test Conditions

Min

Typ

Max

Unit

Start Condition Hold Time

1250

—

—

nsec

Data in Setup Time to SCL High

100

—

—

nsec

Data in Hold Time after SCL Low

0

—

—

nsec

Stop Condition Setup Time

1250

—

—

nsec

Bus Free Time Prior to New

1250

—

—

nsec

Transition

NOTES: 1. Output current should be minimized for best temperature accuracy. Power dissipation within the TCN75 will cause self-heating and

temperature drift. At maximum rated output current and saturation voltage, 4mA and 0.8V, respectively, the error amounts to 0.352

°C for the

PDIP, and 0.544

°C for the SOIC.

2. All part types of the TCN75 will operate properly over the wider power supply range of 2.7V to 5.5V. Each part type is tested and specified

3. Human body model, 100pF discharged through a 1.5k resistor, machine model, 200pF discharged directly into each pin.

PIN DESCRIPTION

Pin Number

Symbol

Description

1

SDA

Bidirectional Serial Data.

2

SCL

Serial Data Clock Input.

3

INT/CMPTR

Interrupt or Comparator Output.

4

GND

System Ground.

Address Select Pin (MSB).

Address Select Pin.

Address Select Pin (LSB).

Power Supply Input.

DETAILED DESCRIPTION

A typical TCN75 hardware connection is shown in

Figure 1.

Serial Data (SDA)

Bidirectional. Serial data is transferred in both directions

using this pin.

Serial Clock (SCL)

Input. Clocks data into and out of the TCN75.

INT/CMPTR

Open Collector, Programmable Polarity. In Comparator

Mode, unconditionally driven active any time temperature

CMPTR will become inactive when temperature subse-

Programmer's Model.) In Interrupt Mode, INT/CMPTR is

ally reset to its inactive state by reading any register via the

CMPTR is again driven active. Reading any register will

output is unconditionally reset upon entering Shutdown

Mode. If programmed as an active-low output, it can be

wire-ORed with any number of other open collector devices.

Most systems will require a pull-up resistor for this configu-

ration.

Note that current sourced from the pull-up resistor

causes power dissipation and may cause internal heating of

the TCN75. To avoid affecting the accuracy of ambient

temperature readings, the pull-up resistor should be made

as large as possible. INT/CMPTR's output polarity may be

programmed by writing to the INT/CMPTR POLARITY bit in

the CONFIG register. The default is active low.

Address (A2, A1, A0)

Inputs. Sets the three least significant bits of the TCN75

8-bit address. A match between the TCN75's address and

the address specified in the serial bit stream must be made

to initiate communication with the TCN75. Many protocol-

compatible devices with other addresses may share the

same 2-wire bus.

Slave Address

The four most significant bits of the Address Byte (A6,

A5, A4, A3) are fixed to 1001[B]. The states of A2, A1 and