Ver: 2.5

Dec 14, 2004

TEL: 886-3-5788833

http://www.gmt.com.tw

9

G767

Global Mixed-mode Technology Inc.

If the remote channel is shorted (DXP to DXN or DXP

to GND), the ADC reads 0000 0000 so as not to trip

In applications that are never subjected to 0

°C in nor-

mal operation, a 0000 0000 result can be checked to

indicate a fault condition in which DXP is accidentally

short circuited. Similarly, if DXP is short circuited to

channels, and the device alarms.

Table 3. Read Format for Alert Response Address

(0001 100)

BIT

NAME

FUNCTION

7(MSB)

ADD7

6

ADD6

5

ADD5

4

ADD4

3

ADD3

2

ADD2

1

ADD1

Provide the current G767

slave address that was

latched at POR (Table 8)

0(LSB)

1

Logic 1

ALERT

Interrupts

The ALERT interrupt output signal is latched and

can only be cleared by reading the Alert Response

disconnected (for continuity fault detection). The inter-

rupt does not halt automatic conversions; new tem-

perature data continues to be available over the

SMBus interface after ALERT is asserted. The in-

terrupt output pin is open-drain so that devices can

share a common interrupt line. The interrupt rate can

never exceed the conversion rate.

The interface responds to the SMBus Alert Response

address, an interrupt pointer return-address feature

(see Alert Response Address section). Prior to taking

corrective action, always check to ensure that an in-

terrupt is valid by reading the current temperature.

Alert Response Address

The SMBus Alert Response interrupt pointer provides

quick fault identification for simple slave devices that

lack the complex, expensive logic needed to be a bus

master. Upon receiving an ALERT interrupt signal,

the host master can broadcast a Receive Byte trans-

mission to the Alert Response slave address (0001

100). Then any slave device that generated an inter-

rupt attempts to identify itself by putting its own ad-

dress on the bus (Table 3).

Table 4. Command-Byte Bit Assignments

REGISTER

COMMAND

POR STATE

FUNCTINON

RLTS

00h

0000 0000*

Read local temperature: returns latest temperature

RRTE

01h

0000 0000*

Read remote temperature: returns latest temperature

RSL

02h

N/A

Read status byte (flags, busy signal)

RCL

03h

0000 0000

Read configuration byte

RCRA

04h

0000 0010

Read conversion rate byte

RLHN

05h

0111 1111

RLLI

06h

1100 1001

RRHI

07h

0111 1111

RRLS

08h

1100 1001

WCA

09h

N/A

Write configuration byte

WCRW

0Ah

N/A

Write conversion rate byte

WLHO

0Bh

N/A

WLLM

0Ch

N/A

WRHA

0Dh

N/A

WRLN

0Eh

N/A

OSHT

0Fh

N/A

One-shot command (use send-byte format)

*If the device is in hardware standby mode at POR, both temperature registers read 0