DS1780E Maxim Integrated Products, DS1780E Datasheet - Page 12

• Manufacturer Part Number: DS1780E
• Description: IC CPU PERIPHERAL MON 24-TSSOP
• Manufacturer: Maxim Integrated Products

Specifications of DS1780E

• Function: Thermal Monitor, CPU Peripherals
• Topology: ADC (Sigma Delta), Comparator, Fan Speed Control, Register Bank
• Sensor Type: Internal
• Sensing Temperature: -40°C ~ 125°C
• Output Type: I²C™/SMBus™
• Output Alarm: No
• Output Fan: Yes
• Voltage - Supply: 2.8 V ~ 5.75 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 24-TSSOP
• Full Temp Accuracy: +/- 12 %
• Digital Output - Bus Interface: Serial (2-Wire)
• Digital Output - Number Of Bits: 8 bit
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

OPERATION - Interrupts
An external interrupt can come from the following sources. While the label suggests a specific type or
source of interrupt, this label is not a restriction on the usage; it could come from any desired source.
1. Analog Voltage: An interrupt will be generated if a analog voltage high or low limit has been
2. Temperature: An interrupt will be generated if a high or a low hot temperature limit has been
3. Fan speed: An interrupt will be generated if a fan count limit has been exceeded.
4. Chassis Intrusion: This is an active high interrupt from any type of device that detects and captures
All System Management Interrupts (SMIs) are indicated in the two Interrupt Status Registers. The
output has individual mask registers and individual masks for each Interrupt. As described in the
“OPERATION - Configuration Register” Section, this hardware Interrupt line can also be
enabled/disabled in the Configuration Register.
Reading an Interrupt Status Register will output the contents of the Register, and reset the Register. A
subsequent read done before the analog ‘round-robin’ monitoring loop is complete will indicate a cleared
Register. Allow at least 1 second to allow all Registers to be updated between reads. In summary, the
Interrupt Status Register clears upon being read, and requires at least 1 second to be updated. When the
Interrupt Status Register clears, the hardwire interrupt line will also clear until the Registers are updated
by the monitoring loop.
The
Register, without affecting the contents of the Interrupt Status Registers. When this bit is high, the
DS1780 monitoring loop will stop. It will resume when the bit is low.
Analog Voltage Limits
The limits for the analog voltage comparison are programmed into the Value RAM at Internal Address
Registers 2Bh - 36h. A high and low limit is associated with each of the 6 analog voltage inputs of the
DS1780. Care must be taken to program the limit registers in the same format as the respective voltage
data register. Please see “OPERATION - Voltage Data Format” for details. For setting a voltage
interrupt, the DS1780 compares on a “greater than” basis for high limits and a “less than or equal to”
basis for low limits. The host can mask any or all of the voltage limits for interrupt contention.
Temperature Limits and Interrupt Modes
The host programs an 8-bit high temperature limit and hysteresis/low temperature limit into the DS1780
at Internal Address Registers 39h and 3 Ah in the same two’s complement format described in the
“OPERATION - Temperature Data Format” section. The temperature mode is programmed into the
Temperature Configuration Register (0x4Bh). A digital 8-bit comparator is also incorporated that
compares the temperature readings to the programmed limits.
There are three interrupt modes of operation. The
interrupt modes of operation and the host can program the DS1780 to completely mask temperature
interrupts from controlling the
exceeded; this is generally when a power supply is out of its normal operating range.
exceeded.
chassis intrusion violations. This could be accomplished mechanically, optically, or electrically, and
circuitry external to the DS1780 is expected to latch the event.
INT
hardware Interrupt output is cleared with the INT_Clear bit, which is Bit 3 of the Configuration
INT
output.
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INT
output can be programmed for either of the three
INT