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ADM1026 数据表(PDF) 10 Page - ON Semiconductor |
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ADM1026 数据表(HTML) 10 Page - ON Semiconductor |
10 / 55 page ADM1026 http://onsemi.com 10 Functional Description The ADM1026 is a complete system hardware monitor for microprocessor-based systems. The device communicates with the system via a serial system management bus. The serial bus controller has a hardwired address line for device selection (ADD, Pin 15), a serial data line for reading and writing addresses and data (SDA, Pin 14), and an input line for the serial clock (SCL, Pin 13). All control and programming functions of the ADM1026 are performed over the serial bus. Measurement Inputs Programmability of the analog and digital measurement inputs makes the ADM1026 extremely flexible and versatile. The device has an 8-bit A/D converter, and 17 analog measurement input pins that can be configured in different ways. Pins 25 and 26 are dedicated temperature inputs and may be connected to the cathode and anode of a remote temperature sensing diode. Pins 27 and 28 may be configured as temperature inputs and connected to a second temperature-sensing diode, or may be reconfigured as analog inputs with a range of 0 V to 2.5 V. Pins 29 to 33 are dedicated analog inputs with on-chip attenuators configured to monitor VBAT, +5.0 V, −12 V, +12 V, and the processor core voltage VCCP, respectively. Pins 34 to 41 are general-purpose analog inputs with a range of 0 V to 2.5 V or 0 V to 3.0 V. These are mainly intended for monitoring SCSI termination voltages, but may be used for other purposes. The ADC also accepts input from an on-chip band gap temperature sensor that monitors system ambient temperature. In addition, the ADM1026 monitors the supply from which it is powered, 3.3 V STBY, so there is no need for a separate pin to monitor the power supply voltage. The ADM1026 has eight pins that are general-purpose logic I/O pins (Pins 1, 2, and 43 to 48), a pin that can be configured as GPIO or as a bidirectional thermal interrupt (THERM) pin (Pin 42), and eight pins that can be configured for fan speed measurement or as general-purpose logic pins (Pins 3 to 6 and Pins 9 to 12). Sequential Measurement When the ADM1026 monitoring sequence is started, it cycles sequentially through the measurement of analog inputs and the temperature sensor, while at the same time the fan speed inputs are independently monitored. Measured values from these inputs are stored in value registers. These can be read over the serial bus, or can be compared with programmed limits stored in the limit registers. The results of out-of-limit comparisons are stored in the interrupt status registers. An out-of-limit event generates an interrupt on the INT line (Pin 17). Any or all of the interrupt status bits can be masked by appropriate programming of the interrupt mask registers. Chassis Intrusion A chassis intrusion input (Pin 16) is provided to detect unauthorized tampering with the equipment. This event is latched in a battery-backed register bit. Resets The ADM1026 has two power-on reset outputs, RESETMAIN and RESETSTBY, that are asserted when 3.3 V MAIN or 3.3 V STBY fall below the reset threshold. These give a 180 ms reset pulse at powerup. RESETMAIN also functions as an active-low RESET input. Fan Speed Control Outputs The ADM1026 has two outputs intended to control fan speed, though they can also be used for other purposes. Pin 18 is an open drain, Pulse Width Modulated (PWM) output with a programmable duty cycle and an output frequency of 75 Hz. Pin 23 is connected to the output of an on-chip, 8-bit, digital-to-analog converter with an output range of 0 V to 2.5 V. Either or both of these outputs may be used to implement a temperature-controlled fan by controlling the speed of a fan using the temperature measured by the on-chip temperature sensor or remote temperature sensors. Internal Registers Table 5 describes the principal registers of the ADM1026. For more detailed information, see Table 12 to Table 125. Table 5. PRINCIPLE REGISTERS Type Description Address Pointer Contains the address that selects one of the other internal registers. When writing to the ADM1026, the first byte of data is always a register address, and is written to the address pointer register. Configuration Registers Provide control and configuration for various operating parameters. Fan Divisor Registers Contain counter prescaler values for fan speed measurement. DAC/PWM Control Registers Contain speed values for PWM and DAC fan drive outputs. GPIO Configuration Registers Configure the GPIO pins as input or output and for signal polarity. Value and Limit Registers Store the results of analog voltage inputs, temperature, and fan speed measurements, along with their limit values. Status Registers Store events from the various interrupt sources. Mask Registers Allow masking of individual interrupt sources. EEPROM The ADM1026 has 8 kB of non-volatile, electrically erasable, programmable read-only memory (EEPROM) from register Addresses 8000h to 9FFFh. This may be used for permanent storage of data that is not lost when the |
类似零件编号 - ADM1026 |
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类似说明 - ADM1026 |
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