ADM1026JST ON Semiconductor, ADM1026JST Datasheet - Page 10

• Manufacturer Part Number: ADM1026JST
• Description: IC CNTRL SYS REF/EEPROM 48LQFP
• Manufacturer: ON Semiconductor

Specifications of ADM1026JST

• Rohs Status: RoHS non-compliant
• Function: Hardware Monitor
• Topology: ADC, Comparator, Multiplexer, Register Bank
• Sensor Type: External & Internal
• Sensing Temperature: 0°C ~ 100°C, External Sensor
• Output Type: SMBus™
• Output Alarm: No
• Output Fan: Yes
• Voltage - Supply: 3 V ~ 5.5 V
• Operating Temperature: 0°C ~ 100°C
• Mounting Type: Surface Mount
• Package / Case: 48-LFQFP

Functional Description
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
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.
be connected to the cathode and anode of a remote
temperature sensing diode.
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.
attenuators configured to monitor V
+12 V, and the processor core voltage V
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.
temperature sensor that monitors system ambient
temperature.
which it is powered, 3.3 V STBY, so there is no need for a
separate pin to monitor the power supply voltage.
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
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).
appropriate programming of the interrupt mask registers.
The ADM1026 is a complete system hardware monitor for
Programmability of the analog and digital measurement
Pins 25 and 26 are dedicated temperature inputs and may
Pins 27 and 28 may be configured as temperature inputs
Pins 29 to 33 are dedicated analog inputs with on−chip
Pins 34 to 41 are general−purpose analog inputs with a
The ADC also accepts input from an on−chip band gap
In addition, the ADM1026 monitors the supply from
The ADM1026 has eight pins that are general−purpose
When the ADM1026 monitoring sequence is started, it
Any or all of the interrupt status bits can be masked by
BAT
CCP
, +5.0 V, −12 V,
, respectively.
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10
Chassis Intrusion
unauthorized tampering with the equipment. This event is
latched in a battery−backed register bit.
Resets
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
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.
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
For more detailed information, see Table 8 to Table 121.
EEPROM
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
Table 1. Principle Registers
A chassis intrusion input (Pin 16) is provided to detect
The ADM1026 has two power−on reset outputs,
The ADM1026 has two outputs intended to control fan
Either or both of these outputs may be used to implement
Table 1 describes the principal registers of the ADM1026.
Configuration
Configuration
The ADM1026 has 8 kB of non−volatile, electrically
Fan Divisor
DAC/PWM
Value and
Registers
Registers
Registers
Registers
Registers
Registers
Registers
Address
Control
Pointer
Status
GPIO
Mask
Type
Limit
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.
Provide control and configuration for
various operating parameters.
Contain counter prescaler values for fan
speed measurement.
Contain speed values for PWM and DAC
fan drive outputs.
Configure the GPIO pins as input or output
and for signal polarity.
Store the results of analog voltage inputs,
temperature, and fan speed measurements,
along with their limit values.
Store events from the various interrupt
sources.
Allow masking of individual interrupt
sources.
Description