5

TCM1617

TCM1617-1 2/5/99

 2001 Microchip Technology Inc.

DS21485A

SMBus Thermal Sensor with External Diode Input

PIN DESCRIPTION

Pin Number

Symbol

Type

Description

Power

Power Supply Input

3

D+

Bi-Directional

Current Source and A/D Positive Input

4

D–

Bi-Directional

Current Sink and A/D Negative Input

6,10

ADD[1:0]

Input

Address Select Pins (See Address Decode Table)

7,8

GND

Power

System Ground

11

ALERT#

Output

SMBus Interrupt (SMBALERT#)

12

SDA

Bi-Directional

SMBus Serial Data

14

SCL

Input

SMBus Serial Clock

15

STBY#

Input

Standby Enable

1,5, 9, 13,16

NC

—

Not Connected

PIN DESCRIPTION

SCL

Input. SMBus serial clock. Clocks data into and out of

the TCM1617. See System Management Bus Specification,

rev. 1.0, for timing diagrams.

SDA

Bi-directional. Serial data is transferred on the SMBus

in both directions using this pin. See System Management

Bus Specification, rev. 1.0, for timing diagrams.

ADD1, ADD0

Inputs. Sets the 7-bit SMBus address. These pins are

“tri-state,” and the SMBus addresses are specified in the

Address Decode Table below.

(NOTE: The tri-state scheme allows up to nine

TCM1617s on a single bus. A match between the TCM1617’s

address and the address specified in the serial bit stream

must be made to initiate communication. Many SMBus-

compatible devices with other addresses may share the

same 2-wire bus (see System Management Bus Specifica-

tion rev. 1.0 for address allocations). These pins are only

active at power-on reset, and will latch into the appropriate

states.

ALERT#

Output, Open Collector, Active Low. The ALERT# out-

put corresponds to the general SMBALERT# signal and

indicates an interrupt event. The TCM1617 will respond to

the standard SMBus Alert Response Address (see SMBus

Specification 1.0) and associated protocol when ALERT# is

asserted. Normally, the ALERT# output will be asserted

when any of the following occurs:

INT_TEMP equal to or exceeds INT_HLIM

INT_TEMP falls below INT_LLIM

EXT_TEMP equal to or exceeds EXT_HLIM

EXT_TEMP falls below EXT_LLIM

External Diode “Open”

The operation of the ALERT# output is controlled by the

MASK1 bit in the CONFIG register. If the MASK1 bit is set to

“1,” no interrupts will be generated on ALERT#. The ALERT#

output is cleared and re-armed by the Alert Response

Address (ARA). This output may be WIRE-ORed with simi-

lar outputs from other SMBus devices. If the alarm condition

persists after the ARA, the ALERT# output will be immedi-

ately re-asserted.

(NOTE: A pull-up resistor is necessary on ALERT#

since it is an open-drain output. Current sourced from the

pull-up resistor causes power dissipation and may cause

internal heating of the TCM1617. To avoid affecting the

accuracy of internal temperature readings, the pull-up resis-

tors should be made as large as possible.)

STBY#

Input. The activation of Standby mode may be achieved

using either the STBY# pin or the CHIP STOP bit (CONFIG

register). If STBY# is pulled low, the TCM1617 uncondition-

The temperature-to-digital conversion process is halted, but

ALERT remains functional. The TCM1617’s bus interface