ADM1026
Pins 29 to 33 are dedicated analog inputs with on-chip
attenuators configured to monitor VBAT, +5 V, −12 V, +12 V,
and the processor core voltage VCCP, respectively.
PRODUCT DESCRIPTION
The ADM1026 is a complete system hardware monitor for
microprocessor-based systems, providing measurement and
limit comparison of various system parameters. The ADM1026
has up to 19 analog measurement channels. Fifteen analog
voltage inputs are provided, five of which are dedicated to
monitoring +3.3 V, +5 V, and 12 V power supplies, and the
processor core voltage. The ADM1026 can monitor two other
power supply voltages by measuring its own VCC and the main
system supply. One input (two pins) is dedicated to a remote
temperature-sensing diode. Two additional pins can be
configured as general-purpose analog inputs to measure
0 V to 2.5 V, or as a second temperature sensing input. The eight
remaining inputs are general-purpose analog inputs with a
range of 0 V to 2.5 V or 0 V to 3 V. The ADM1026 also has an
on-chip temperature sensor.
Pins 34 to 41 are general-purpose analog inputs with a range
of 0 V to 2.5 V or 0 V to 3 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 (
) pin
THERM
The ADM1026 has eight pins that can be configured for fan
speed measurement or as general-purpose logic I/O pins.
Another eight pins are dedicated to general-purpose logic I/O.
An additional pin can be configured as a general-purpose I/O
(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
or as the bidirectional
pin.
THERM
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
Measured values can be read out via a 2-wire serial system
management bus, and values for limit comparisons can be
programmed over the same serial bus. The high speed,
successive approximation ADC allows frequent sampling of all
analog channels to ensure a fast interrupt response to any out-
of-limit measurement.
FUNCTIONAL DESCRIPTION
generates an interrupt on the
line (Pin 17).
INT
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.
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
Measurement Inputs
The ADM1026 has two power-on reset outputs,
RESETMAIN
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.
and
, that are asserted when 3.3 V MAIN or 3.3 V
RESETSTBY
STBY fall below the reset threshold. These give a 180 ms reset
pulse at power-up.
RESET input.
also functions as an active-low
RESETMAIN
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.
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