DS1780 Dallas, DS1780 Datasheet
DS1780
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DS1780 Summary of contents
Page 1
... + +2.5 V /+V S CCP2 12 13 GNDA DS1780E - Address Input / NAND Output - Address Input - 2-Wire Serial Data Input/Output - 2-Wire Serial Clock - Tachometer Inputs - Chassis Intrusion Detector Input - Digital Ground - Power Supply Voltage (2.8V to 5.75V) - Hardware Interrupt output - DAC output / NAND TREE ...
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... 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 ...
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... When the DS1780 is started, it cycles through each measurement in sequence, and it continuously loops through the sequence approximately once every second. Each measured value is compared to values stored in limit registers. When the measured value violates the programmed limit the DS1780 will set a corresponding System Management Interrupt (SMI) in the Interrupt Status Registers. One hardware interrupt line available to generate an SMI ...
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... 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 ...
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... Register 2 Chassis Intrusion Clear Register VID Register Serial Address Register VID4 Register Temperature Configuration Register Test Register Analog output Value RAM Company ID Stepping DS1780 INTERNAL POWER ON VALUE HEX ADDRESS 40h 41h 42h 43h 44h 46h 47h 48h 49h 4Bh 15h 19h ...
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... 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 ...
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... Hardware Reset - This condition is generated by some external source pulling the VIN(0) (see DC Electrical Characteristics). The DS1780 will then force the active low state for >20 ms. It will clear all registers in DS1780 memory to their default state except the Value RAM (0x20h - 0x3Dh) and analog output (0x19h). These locations will remain unchanged from their state before the Hardware Reset ...
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... Since these inputs can be greater than V small external series resistors such as 510Ω should be put into the lines driving the DS1780 to prevent damaging the traces or power supplies should an accidental short connect two power supplies together. ...
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... CCP ) must be used (see Figure 1) such that input voltage to the DS1780 REF is a perfect supply, then the resolution and range of -12V input are +5V , +3. NOM +3.3V IN 17.2 PIN VOLTAGE (V) ...
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... OPERATION - FAN Speed Data Format Inputs are provided for signals from fans equipped with tachometer outputs. These are logic-level inputs with an approximate threshold of 1.4V. Signal conditioning in the DS1780 accommodates the slow rise and fall times typical of fan tachometer outputs. The maximum input signal range event these inputs are supplied from fan outputs which exceed clamping must be included to keep inputs within an acceptable range, as shown in Figure 3 ...
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... Count (RPM, Divisor) RPM If fans can be powered while the power to the DS1780 is off, the DS1780 inputs will provide diode clamping. Limit input current to the Input Current at Any Pin specification shown in the ABSOLUTE MAXIMUM RATINGS section. In most cases, open collector outputs with pullup resistors inherently limit this current ...
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... 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. ...
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... This could be accomplished mechanically, optically, or electrically, and circuitry external to the DS1780 is expected to latch the event. The design of the DS1780 allows this input to go high even with no power applied to the DS1780, and no clamping or other interference with the line will occur. This line can also be pulled low for at least the DS1780 to reset a typical Chassis Intrusion circuit ...
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TEMPERATURE INTERRUPT MODE ILLUSTRATION Figure 4 SAMPLE CHASSIS INTRUSION DETECTOR/LATCH Figure ...
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... 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 ...
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... ATE (Automatic Test Equipment) to drive it high. DS1780 NAND TREE TEST FLOW Figure 7 DS1780 REGISTERS AND RAM INTERNAL ADDRESS REGISTER Table 10.0 ...
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... Logic 1 enables startup of measurement loop, logic 0 places the DS1780 in standby mode. Caution: The 0 START R/W interrupt has occurred (see “ scanning begins. Note, all HIGH and LOW LIMITS should be set into the DS1780 prior to turning on this bit. (Power-up default=0). 1 INT Enable R/W Logic 1 enables the ...
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INTERRUPT INT STATUS REGISTER 2 (ADDRESS 0X42; POWER-UP DEFAULT=00h) Table 10.4 BIT NAME R/W 0 +12V_Error indicates a High or Low limit has been exceeded. -12V indicates a High or Low limit has ...
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RESERVED REGISTER (ADDRESS 0X45; POWER-UP DEFAULT=00h) Table 10.7 BIT NAME R/W RESERVED R/W Undefined (Power On = 00h). <7:0> CHASSIS INTRUSION CLEAR REGISTER (ADDRESS 0X46; POWER-UP DEFAULT=00h) Table 10.8 BIT NAME R/W 0-6 RESERVED R/W Undefined (Power On = 00h). ...
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TEMPERATURE CONFIGURATION REGISTER (ADDRESS Ox4B; POWER-UP DEFAULT = 01h) Table 10.12 BIT NAME R/W 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 ...
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VALUE RAM (ADDRESS 0x15h - 0x3Dh) Table 10.15 ADDRESS <A7:A0>h R/W 20h 21h 22h 23h 24h 25h 26h 27h 28h 29h 2Ah R/W 2Bh R/W 2Ch R/W 2Dh R/W 2Eh R/W 2Fh R/W 30h R/W 31h R/W 32h R/W 33h ...
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... Exposure to absolute maximum rating conditions for extended periods of time may affect reliability. The Dallas Semiconductor DS1780 is built to the highest quality standards and manufactured for long term reliability. All Dallas Semiconductor devices are made using the same quality materials and manufacturing methods ...
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DC ELECTRICAL CHARACTERISTICS Power Supply PARAMETER SYMBOL Supply Current ELECTRICAL CHARACTERISTICS: Temperature-to-Digital Converter PARAMETER SYMBOL Thermometer Error T ERR Resolution DC ELECTRICAL CHARACTERISTICS: Voltage-to-Digital Converter PARAMETER SYMBOL ADC Resolution Voltage to Digital Conversion Resolution (See Voltage A/D ...
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DC ELECTRICAL CHARACTERISTICS: Fan RPM-to-Digital Converter PARAMETER SYMBOL Accuracy Full scale count FAN1 & FAN2 Normal Input RPM Internal Oscillator Frequency DC ELECTRICAL CHARACTERISTICS: Analog Output V OUT PARAMETER SYMBOL DAC Resolution Voltage Range Error DAC Output Current I OUT ...
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DC ELECTRICAL CHARACTERISTICS: Open-drain Digital Outputs: PARAMETER SYMBOL Logical 0 V OUT Output Voltage High Level I OH Output Current Active Pulse Width DC ELECTRICAL CHARACTERISTICS: Open-drain 2-Wire Bus Output: SDA PARAMETER SYMBOL Logical 0 V OUT Output Voltage High ...
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DC ELECTRICAL CHARACTERISTICS: All Digital Inputs PARAMETER SYMBOL Logical Input Current Logical Input Current Input Capacitance C AC ELECTRICAL CHARACTERISTICS: 2-Wire Interface PARAMETER SYMBOL SCL Clock Period t Data In Setup t Time to ...
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BUS TIMING DIAGRAM Figure 8 NOTES: 1. All voltages are referenced to ground, unless otherwise specified. 2. When the input voltage (VIN) at any pin exceeds the power supplies (V >V , except for analog voltage inputs), the current ...
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... DS1780 24 LD. TSSOP DIM MIN MAX - 1. 0.75 1.05 A2 0.09 0.18 c 0° 8° phi 0.50 0.70 L 0.65 BSC e1 0.18 0.30 B 7.55 8.00 D 4.40 NOM E 0.25 REF G 6.25 6.55 H NOTES: DIMENSION “D” INCLUDES MOLD 1. MISSMATCH, FLASH, AND PROTRUSIONS ...