Ver: 2.5

Dec 14, 2004

TEL: 886-3-5788833

http://www.gmt.com.tw

4

G767

Global Mixed-mode Technology Inc.

Pin Description

PIN

NAME

FUNCTION

1,5,9,13,16

N.C.

No Connection. Not internally connected. May be used for PC board trace routing

2

Vcc

Supply Voltage Input , 3V to 5.5V. Bypass to GND with a 0.1µF capacitor. A 200

recommended but not required additional noise filtering.

3

DXP

Combined Current Source and A/D Positive Input for remote-diode channel. Do not leave DXP float-

ing; tie DXP to DXN if no remote diode is used. Place a 2200pF capacitor between DXP and DXN for

noise filtering.

4

DXN

Combined Current Sink and A/D Negative Input.

6

ADD1

SMBus Address Select pin (Table 8). ADD0 and ADD1 are sampled upon power-up. Excess capaci-

tance (>50pF) at the address pins when floating may cause address-recognition problems.

7,8

GND

Ground

10

ADD0

SMBus Slave Address Select pin

11

ALERT

SMBus Alert (interrupt) Output, open drain

12

SMBDATA SMBus Serial-Data Input / Output , open drain

14

SMBCLK SMBus Serial-Clock Input

15

STBY

Hardware Standby Input. Temperature and comparison threshold data are retained in standby mode.

Low = standby mode, high = operate mode.

Detailed Description

The G767 is a temperature sensor designed to work in

conjunction with an external microcontroller (µC) or

other intelligence in thermostatic, process-control, or

monitoring applications. The µC is typically a

power-management or keyboard controller, generating

SMBus serial commands by “bit-banging” gen-

eral-purpose input-output (GPIO) pins or via a dedi-

cated SMBus interface block.

Essentially an 8-bit serial analog-to digital converter

(ADC) with a sophisticated front end, the G767 con-

tains a switched current source, a multiplexer, an ADC,

an SMBus interface, and associated control logic (Fig-

ure 1). Temperature data from the ADC is loaded into

two data registers, where it is automatically compared

with data previously stored in four over/under- tem-

perature alarm registers.

ADC and Multiplexer

The ADC is an averaging type that integrates over a

60ms period (each channel, typical), with excellent

noise rejection.

The multiplexer automatically steers bias currents

through the remote and local diodes, measures their

forward voltages, and computes their temperatures.

Both channels are automatically converted once the

conversion process has started, either in free-running

or single-shot mode. If one of the two channels is not

used, the device still performs both measurements,

and the user can simply ignore the results of the un-

used channel. If the remote diode channel is unused,

tie DXP to DXN rather than leaving the pins open.

The worst-case DXP-DXN differential input voltage

range is 0.25V to 0.95V.

Excess resistance in series with the remote diode

causes about +1/2°C error per ohm. Likewise, 200µV

of offset voltage forced on DXP-DXN causes about

1°C error.