DS1780 CPU Peripheral Monitor www.dalsemi.com FEATURES PIN ASSIGNMENT Direct-to-digital temperature sensor requires VID0 A0/NT 1 24 OUT no external components or user calibration A1 2 23 VID Two fan speed sensors SDA VID2 3 22 Monitors 6 power supply voltages SCL 4 21 VID3 FAN1 5 20 VID4 8-bit DAC for fan speed control FAN2 +V 6 19 CCP1 Intrusion detect for security (detects when CHS 7 18 +2.5 V IN chassis lid has been removed, even if power is GNDD +3.3 V 8 17 IN off) V 9 16 +5 V DD IN INT 10 15 +12 V IN Remote system reset V /NT +2.5 V /+V OUT IN 11 14 S CCP2 System interrupt availability on all monitored RST 12 13 GNDA functions (temperature, voltages, fan speed, DS1780E+ chassis intrusion) 24-Pin TSSOP (173-mil) 2-wire interface with 2-bit addressability Integrated NAND TREE for board level PIN DESCRIPTION testability A0/NT - Address Input / NAND OUT Wide power supply range (2.8V V DD TREE Output 5.75V) A1 - Address Input High integration in a small 24-pin 173-mil SDA - 2-Wire Serial Data TSSOP Input/Output Applications include monitoring of personal SCL - 2-Wire Serial Clock computers or any microprocessor-based FANx - Tachometer Inputs system CHS - Chassis Intrusion Detector Input GNDD - Digital Ground V - Power Supply Voltage (2.8V DD to 5.75V) INT - Hardware Interrupt output V /NT - DAC output / NAND TREE OUT IN Input RST - Remote System Reset GNDA - Analog Ground +xxV - Positive Voltage Inputs IN +2.5V /+V - Positive/negative Voltage S CCP2 Input VIDx - Processor Voltage Supply Readout Inputs See Table 11 on page 27 for Ordering Information 1 of 28 032305 DS1780 DESCRIPTION The DS1780 is a highly integrated system instrumentation monitor ideal for use in personal computers, or any microprocessor-based system. It monitors ambient temperature, six power supply voltages, and the speed of two fans. Fan speed can also be controlled with the use of an internal 8-bit DAC. All measurements are internally converted to a digital format for easy processing by the CPU. The DS1780 can be reset to its default power-up state via a remote reset function with internal debounce and delay. It features an interrupt that can be programmed to become active should any of the functions the DS1780 is monitoring fall out of spec. For board-level testability, an internal NAND TREE function simplifies the system design. A chassis intrusion input is featured to enhance system security. Programming and data readout are accessed via a simple 2-wire interface with 2-bit addressability. The DS1780 power supply range of 2.8V to 5.75V allows for monitoring of parameters for 3V or 5V systems. The DS1780 is assembled in a compact 173-mil TSSOP package. Detailed Pin Description Table 1 PIN SIGNAL DIRECTION DESCRIPTION The lowest order programmable bit of the 2-wire bus address. This pin 1 A0/NT Digital I/O OUT functions as an output when doing a NAND TREE test. 2 A1 Digital Input The highest order programmable bit of the 2-wire bus address. 3 SDA Digital I/O 2-wire bus bi-directional data. Open-drain output. 4 SCL Digital Input 2-wire bus synchronous clock. 5 FAN1 Digital Input 0 to V amplitude fan tachometer input. DD 6 FAN2 Digital Input 0 to V amplitude fan tachometer input. DD An active high input from an external circuit, which latches a Chassis Intrusion event. This line can go high without any clamping action regardless 7 CHS Digital I/O of the powered state of the DS1780. The DS1780 provides an internal open drain on this line, controlled by Bit 6 of Configuration Register, to provide a minimum 20 ms reset of this signal. 8 GNDD GROUND Internally connected to all digital circuitry. power. Bypass with the parallel combination of 10 F +3.3V or +5V V DD 9 V POWER DD (Electrolytic or Tantalum) and 0.1 F (ceramic) bypass capacitors. Active-low Programmable interrupt output. The output is enabled when Bit 1 10 Digital Output INT of the Configuration Register is set to 1. The default state is disabled. An active-high input that enables NAND Tree board-level connectivity Digital Input/ 11 V /NT testing. Refer to NAND Tree Testing Section. Used as DAC output when OUT IN Analog Output NAND Tree is not selected. Master Reset, 5 mA open drain driver, active low output with at least a 20 ms 12 Digital I/O minimum pulse width. Available when enabled via Bit 4 in Configuration RST Register. This is a bi-directional I/O pin. It acts as power on RESET input. Internally connected to all analog circuitry. The ground reference for all 13 GNDA GROUND analog inputs. Analog input for monitoring -12V or +V . DS1780 will measure voltages CCP2 14 +2.5V /+V Analog Input on this pin from 0V to 3.6V. An external resistor ladder is required for S CCP2 monitoring a -12V supply (see Figure 1). 15-19 +xxV Analog Inputs A/D inputs for 5 positive voltages. IN Voltage supply readouts from the processor. These values are read in the VID 20-24 VIDx Digital Inputs and VID4 Status Registers. 2 of 28