 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
G781 Datasheet(PDF) 4 Page - List of Unclassifed Manufacturers |
|
||||||||||||||||||||||||||||||
G781 Datasheet(HTML) 4 Page - List of Unclassifed Manufacturers |
|
|
4 / 14 page 
Ver: 1.0 Oct 02, 2002 TEL: 886-3-5788833 http://www.gmt.com.tw 4 Global Mixed-mode Technology Inc. G781 Detailed Description The G781 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” general- purpose input-output (GPIO) pins or via a dedicated SMBus interface block. Essentially an serial analog-to digital converter (ADC) with a sophisticated front end, the G781 contains a switched current source, a multiplexer, an ADC, an SMBus interface, and associated control logic (Figure 1). Temperature data from the ADC is loaded into two data registers, where it is automatically compared with data previously stored in several 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 +0.6°C error per ohm. Likewise, 240µV of offset voltage forced on DXP-DXN causes about 1°C error. Figure 1. Functional Diagram V CC DXP DXN MUX + + + REMOTE LOCAL ADC CONTROL LOGIC SMBUS 7 SMBDATA SMBCLK READ WRITE DIODE FAULT 2 8 8 COMMAND BYTE (INDEX) REGISTER STATUS BYTE REGISTER CONFIGURATION BYTE REGISTER CONVERSION RATE REGISTER ALERT RESPONSE ADDRESS REGISTER 8 8 LOCAL EMPERATURE DATA REGISTER HIGH-TEMPETATURE THRESHOLD (LOCALTHIGH ) LOW-TEMPETATURE THRESHOLD (LOCAL TLOW ) 8 DIGITAL COMPARATOR (LOCAL) SELECTED VIA SLAVE ADD = 0001 100 11 11 ALERT Q S R REMOTE TEMPERATURE DATA REGISTER HIGH-TEMPETATURE THRESHOLD (REMOTE HIGH) LOW-TEMPETATURE THRESHOLD (REMOTE LOW) DIGITAL COMPARATOR (REMOTE) THERM LIMIT AND HYSTERESIS REGISTER 11 COMPARATOR THERM V CC DXP DXN MUX + + + REMOTE LOCAL ADC CONTROL LOGIC SMBUS 7 SMBDATA SMBCLK READ WRITE DIODE FAULT 2 8 8 COMMAND BYTE (INDEX) REGISTER STATUS BYTE REGISTER CONFIGURATION BYTE REGISTER CONVERSION RATE REGISTER ALERT RESPONSE ADDRESS REGISTER 8 8 LOCAL EMPERATURE DATA REGISTER HIGH-TEMPETATURE THRESHOLD (LOCALTHIGH ) LOW-TEMPETATURE THRESHOLD (LOCAL TLOW ) 8 DIGITAL COMPARATOR (LOCAL) SELECTED VIA SLAVE ADD = 0001 100 11 11 ALERT Q S R REMOTE TEMPERATURE DATA REGISTER HIGH-TEMPETATURE THRESHOLD (REMOTE HIGH) LOW-TEMPETATURE THRESHOLD (REMOTE LOW) DIGITAL COMPARATOR (REMOTE) THERM LIMIT AND HYSTERESIS REGISTER 11 COMPARATOR THERM |
English ▼
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
