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G751-1P1 Datasheet(PDF) 4 Page - Global Mixed-mode Technology Inc |
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G751-1P1 Datasheet(HTML) 4 Page - Global Mixed-mode Technology Inc |
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Ver: 2.4 Nov 26, 2002 TEL: 886-3-5788833 http://www.gmt.com.tw 4 G751 Global Mixed-mode Technology Inc. 0,1111,1010 +125°C -55°C -25°C -0.5°C 0°C +0.5°C +25°C Temperature 0,0011,0010 0,0000,0001 0,0000,0000 1,1111,1111 1,1100,1110 1,1001,0010 Temperature-to-Digital Transfer Function (Non-linear scale for clarity) Functional Description The G751 temperature sensor incorporates a band-gap type temperature sensor and 9-bit ADC (Delta-Sigma Analog- to-Digital Converter). The temperature data output of the G751 is available at all times via the SMBus. If a conversion is in pro- gress, it will be stopped and restarted after the read. A digital comparator is also incorporated that com- pares a series of readings, the number of which is user-selectable, to user-programmable setpoint and hysteresis values. The comparator trips the O.S. output line, which is programmable for mode and polarity. O.S. Output, TOS and THYST Limits In Comparator mode the O.S. Output behaves like a thermostat. The output becomes active when tem- perature exceeds the TOS limit, and leaves the active state when the temperature drops below the THYST limit. In this mode the O.S. output can be used to turn a cooling fan on, initiate an emergency system shutdown, or reduce system clock speed. Shutdown mode does not reset O.S. state in a comparator mode. In interrupt mode exceeding TOS also makes O.S. active but O.S. will remain active indefinitely until reset by reading any register via the SMBus inter- face. Once O.S. has been activated by crossing TOS, then reset, it can activated again only by Tempera- ture going below THYST. Again, it will remain active indefinitely until being reset by a read. Placing the G751 in shutdown mode also resets the O.S. output. Default Modes G751 always powers up in a known state. G751 power up default conditions are: 1. Comparator mode 2. TOS set to 50°C for G751-1, to 80°C for G751-2 3. THYST set to 45°C for G751-1, to 75°C for G751-2 4. O.S. active low 5. Pointer set to “00”; Temperature Register With these operating conditions G751 can act as a stand-alone thermostat with the above temperature settings. Connection to an SMBus is not required. SMBus Interface The G751 operates as a slave on the SMBus, so the SMBCLK line is an input (no clock is generated by the G751) and the SMBDATA line is a bi-directional serial data path. According to SMBus specifications, the G751 has a 7-bit slave address. The four most significant bits of the slave address are hard wired inside the G751 and are “1001”. The three least sig- nificant bits of the address are assigned to pins A2-A0, and are set by connecting these pins to ground for a low, (0); or to +Vs for a high, (1). Therefore, the complete slave address is: 1 0 0 1 A2 A1 A0 MSB LSB |
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