DS1780 CPU Peripheral Monitor www.dalsemi.
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.
DS1780 OVERVIEW A block diagram of the DS1780 is shown in Figure 1. The DS1780 provides six analog inputs, an analog output, five digital inputs, two fan speed inputs, a temperature sensor, and interrupt registers on a single chip, which communicates on a 2-wire serial bus. The DS1780 performs power supply, temperature, and fan monitoring for personal computers. The analog voltages are divided internally by the DS1780. The inputs are then converted to 8-bit digital words.
DS1780 A CHS (Chassis Intrusion) digital input is provided. The Chassis Intrusion input is designed to accept an active high signal from an external circuit that latches when the case is removed from the computer; this pin is a dual purpose pin which will be driven low by the DS1780 to reset the external circuit. DS1780 FUNCTIONAL BLOCK DIAGRAM Figure 1 Note: R1 and R2 on the -12V resistance ladder should be ratioed such that approximately +2.5V appears at the input pin (i.e., R1=4kΩ, R2=23.2 kΩ).
DS1780 INTERNAL ADDRESS REGISTER MAP Table 2 REGISTER Configuration Register Interrupt (INT) Status Register 1 Interrupt (INT) Status Register 2 Interrupt (INT) Mask Register 1 Interrupt (INT) Mask Register 2 DS1780 INTERNAL HEX ADDRESS 40h POWER ON VALUE NOTES 0000 1000 41h 0000 0000 42h 0000 0000 43h 0000 0000 44h 0000 0000 Bit 7 of this register clears Chassis Intrusion. The other bits are reserved. The lower 4 bits reflect the state of VID0-VID3 pins.
DS1780 2-WIRE SERIAL COMMUNICATION WITH THE DS1780 Figure 2 OPERATION - Power-on Applying power to the DS1780 causes a reset of several of the registers. Power-on conditions of the registers are shown in Table 2 above. Some registers have indeterminate power-on values, such as the Limit and RAM registers of the Value RAM page, and these are not shown in the table. Upon power-up the ADC is inactive. Writing Limits into the Value RAM should usually be the first action performed after power up.
DS1780 Software Reset - This condition is generated by writing a 1 to bit 4 of the configuration register. It has no effect on DS1780 register contents. It will however pull the RST output to the active low state for a duration of 20 ms (minimum). When the RST output goes active, this bit in the configuration register will clear itself. A Software Reset is only possible if Bit 7 of the INT Mask Register 2 (0x44h) is set to “1”.
DS1780 DS1780 MONITORING ORDER Table 3 TEMPERATURE READING ANALOG +2.5 VS/VCCP2 ANALOG +12V ANALOG +5V ANALOG +3.3V ANALOG +2.5V ANALOG +VCCP1 FAN1 FAN2 If conversions are terminated by either of the methods described in the “OPERATION - Configuration Register” section, the current “round-robin” loop will be completed and the results stored in RAM. Monitoring will then terminate. When the monitoring again commences, monitoring always starts with the temperature reading.
DS1780 The worse such accident would be connecting -12V to +12V; a total of 24V difference, with the series resistors this would draw a maximum of approximately 24 ma. The internal scaling factor depends upon the particular input. The +12VIN, +5VIN, +3.3VIN, and +2.5VIN inputs are internally scaled such that the nominal value of the respective supply corresponds to 3/4 of full range, or a decimal count of 192.
DS1780 VMIN (VREF, R1, R2) @ - R2 R1 VREF R1 + R2 ù VMAX (VREF, R1, R2) @ VREF-(VREF-3.6) éê ú ë R1 û If the +2.5VS/+VCCP2 is to be used to monitor a secondary processor core voltage (VCCP2), R2 should be removed and R1=500Ω. Table 6 below shows the voltage/data relationship for these inputs in the ideal case. In this example, VREF=+5.0V, R1=4.0 kΩ, and R2=23.2 kΩ. Analog inputs will provide best accuracy when referred to the GNDA pin.
DS1780 maximum possible input up to VDD for best noise immunity. Alternatively, use a shunt reference or Zener diode to clamp the input level. Tables 7 and 8 describe the format of the data stored in the FAN reading registers (Internal Address Registers 28h and 29h). FAN TACHOMETER INPUT OPTIONS Figure 3 VOLTAGE/DATA RELATIONSHIPS FOR FAN INPUTS (FAN1, FAN2) UNDER DEFAULT (÷2) MODE Table 7 RPM 4400 3080 2640 Timer Per Revolution 13.64 ms 19.48 ms 22.
DS1780 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 exceeded; this is generally when a power supply is out of its normal operating range. 2.
DS1780 1. One-time Interrupt mode: Exceeding hot temperature limit causes an SMI that will remain active indefinitely until reset by reading Interrupt Status Register 1 or cleared by the INT_Clear bit in the Configuration register. Once an SMI event has occurred by crossing the hot temperature limit, then subsequently reset, an SMI will not occur again until the temperature goes below hot temperature hysteresis (low) limit. 2.
DS1780 TEMPERATURE INTERRUPT MODE ILLUSTRATION Figure 4 SAMPLE CHASSIS INTRUSION DETECTOR/LATCH Figure 5 14 of 28
DS1780 OPERATION - Analog Output The DS1780 has a single analog output from a unsigned 8-bit D/A which produces 0-1.25 volts; this is amplified and scaled with external circuitry such as a op-amp and transistor to provide fan speed control. This register is set to 0xFF on power-up, which produces full fan speed. The analog output register (19h) is unaffected by any reset other than power-on.
DS1780 Note: To properly implement the NAND TREE test on the PCB, no pins listed in the tree should be connected directly to power or ground; if a pin is needed to configure as a permanent low such as an address, it should be connected to ground through a low value resister such as 330 (to allow the ATE (Automatic Test Equipment) to drive it high. DS1780 NAND TREE TEST FLOW Figure 7 DS1780 REGISTERS AND RAM INTERNAL ADDRESS REGISTER Table 10.
DS1780 CONFIGURATION REGISTER (ADDRESS 0X40; POWER-UP DEFAULT = 08h) Table 10.2 BIT NAME R/W 0 START R/W 1 2 INT Enable Reserved R/W R/W 3 INT Clear R/W 4 RESET R/W 5 Reserved R/W 6 CHS Reset R/W 7 Initialization R/W DESCRIPTION Logic 1 enables startup of measurement loop, logic 0 places the DS1780 in standby mode. Caution: The INT output pin will not be cleared if the user writes a 0 to this location after an interrupt has occurred (see “ INT Clear” bit).
DS1780 INTERRUPT INT STATUS REGISTER 2 (ADDRESS 0X42; POWER-UP DEFAULT=00h) Table 10.4 BIT 0 1 2 3 4 5 6 7 NAME +12V_Error -12V/ VCCP2_Error Reserved Reserved Chassis_Error Reserved Reserved Reserved R/W R DESCRIPTION A 1 indicates a High or Low limit has been exceeded. R A 1 indicates a High or Low limit has been exceeded. R R R R R R 0 0 A 1 indicates Chassis Intrusion has gone high. 0 0 0 Note: Anytime the INT Status Registers are read out, the conditions (i.e.
DS1780 RESERVED REGISTER (ADDRESS 0X45; POWER-UP DEFAULT=00h) Table 10.7 BIT <7:0> NAME RESERVED R/W R/W DESCRIPTION Undefined (Power On = 00h). CHASSIS INTRUSION CLEAR REGISTER (ADDRESS 0X46; POWER-UP DEFAULT=00h) Table 10.8 BIT 0-6 7 NAME RESERVED Chassis Int Clear R/W R/W R/W DESCRIPTION Undefined (Power On = 00h). A 1 outputs a minimum 20 ms active low pulse on the Chassis Intrusion (CHS) pin. The register bit clears itself after the pulse has been output.
DS1780 TEMPERATURE CONFIGURATION REGISTER (ADDRESS Ox4B; POWER-UP DEFAULT = 01h) Table 10.12 BIT NAME R/W 0 Hot Temperature Interrupt mode select Bit 0 DESCRIPTION If Bits 0 and Bits 1 of this register are both 0 or both 1, this selects the default interrupt mode which gives the user an interrupt if the temperature goes above the hot limit. The interrupt will be cleared once the status register is read, but it will again be generated when the next conversion has completed.
DS1780 VALUE RAM (ADDRESS 0x15h - 0x3Dh) Table 10.15 ADDRESS h 20h 21h 22h 23h 24h 25h 26h 27h R/W R R R R R R R R 28h R 29h R 2Ah 2Bh 2Ch 2Dh 2Eh 2Fh 30h 31h 32h 33h 34h 35h 36h 37h 38h 39h 3Ah R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W 3Bh R/W 3Ch R/W 3Dh 3Eh 3Fh R R R/W R/W DESCRIPTION +2.5V Input Reading. VCCP1 Input Reading. +3.3V Input Reading. +5V Input Reading. +12V Input Reading. +2.5V_Sense/VCCP2 Input Reading. Reserved.
DS1780 4. This register will latch an 8-bit value into an R-2R D/A to provide a range of 0-1.25 volts; accuracy can be ±5% or more. 5. This location will contain the company identification number which will be used by software to determine analog voltage curves; this register is read only. 6. This location will contain the stepping number of the part; this register is read only.
DS1780 DC ELECTRICAL CHARACTERISTICS Power Supply PARAMETER Supply Current SYMBOL IDD CONDITION Active ADC and DAC, Interface Inactive ADC, DAC and Interface Inactive Inactive ADC and Interface, DAC Active DC ELECTRICAL CHARACTERISTICS: Temperature-to-Digital Converter PARAMETER Thermometer Error SYMBOL TERR Resolution CONDITION -40°C£TA £125°C -25°C£TA £100°C DC ELECTRICAL CHARACTERISTICS: Voltage-to-Digital Converter PARAMETER ADC Resolution SYMBOL Voltage to Digital Conversion Resolution (See
DS1780 DC ELECTRICAL CHARACTERISTICS: Fan RPM-to-Digital Converter PARAMETER SYMBOL Accuracy Full scale count CONDITION 0°C£TA £100°C -40°C£TA £+125°C Internal Oscillator Frequency DC ELECTRICAL CHARACTERISTICS: Analog Output VOUT Error Output Current Load Capacitance SYMBOL CONDITION TYP MAX ±12 255 4400 RPM 1100 21.15 22.5 23.85 Logical “0” Output Voltage VOUT(0) kHz (-40°C to +125°C, 2.8V £ VDD £ 5.75V) MIN TYP MAX 8 1.25 2.
DS1780 DC ELECTRICAL CHARACTERISTICS: Open-drain Digital Outputs: RST , CHS, INT (-40°C to +125°C, 2.8V £ VDD £ 5.75V) PARAMETER Logical 0 Output Voltage High Level Output Current Active Pulse Width SYMBOL VOUT(0) IOH CONDITION IOUT=±5 mA at VDD=5.75V IOUT=±3 mA at VDD=3.45V RST SYMBOL Logical 0 Output Voltage VOUT(0) High Level Output Current IOH PARAMETER Logical 1 Input Voltage Logical 0 Input Voltage SYMBOL 20 CONDITION VIN(1) UNITS NOTES 100 45 µA ms (-40°C to +125°C, 2.
DS1780 DC ELECTRICAL CHARACTERISTICS: All Digital Inputs PARAMETER Logical 1 Input Current Logical 0 Input Current Input Capacitance SYMBOL CONDITION IIN(1) VIN=VDD IIN(0) VIN=0V MIN TYP -1 -0.005 0.005 CIN SYMBOL t1 MAX CONDITION UNITS NOTES µA 1 20 AC ELECTRICAL CHARACTERISTICS: 2-Wire Interface PARAMETER SCL Clock Period Data In Setup Time to SCL High Data Out Stable after SCL Low SDA Low Setup Time to SCL Low (START) SDA High Hold Time after SCL High (STOP) (-40°C to +125°C, 2.
DS1780 2-WIRE BUS TIMING DIAGRAM Figure 8 NOTES: 1. All voltages are referenced to ground, unless otherwise specified. When the input voltage (VIN) at any pin exceeds the power supplies (VIN< (GND or GNDA) or VIN >VDD, except for analog voltage inputs), the current at that pin should be limited to 5 mA. The 20 mA maximum package input current rating limits the number of pins that can safely exceed the power supplies with an input current of 5 mA to four. 2. Solder according to IPC standards. 3.
DS1780 DS1780 24 LD. TSSOP NOTES: 1. DIM A A1 A2 c phi L e1 B D E G H DIMENSION “D” INCLUDES MOLD MISSMATCH, FLASH, AND PROTRUSIONS. MIN MAX 1.10 0.05 0.75 1.05 0.09 0.18 0° 8° 0.50 0.70 0.65 BSC 0.18 0.30 7.55 8.00 4.40 NOM 0.25 REF 6.25 6.
