ADM1033ARQ-REEL7 Просмотр технического описания (PDF) - Analog Devices
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ADM1033ARQ-REEL7 Datasheet PDF : 40 Pages
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ADM1033
FUNCTIONAL DESCRIPTION
The ADM1033 is a local and remote temperature monitor
and fan controller used in a variety of applications, including
microprocessor-based systems. The device accurately monitors
remote and ambient temperature and uses that information to
quietly control the speed of a cooling fan. Whenever the fan
stalls, the device asserts a FAN_FAULT output.
The ADM1033 has a THERM I/O. As an input, this measures
assertions on the THERM pin. As an output, it asserts a low
signal to indicate when the measured temperature exceeds the
programmed THERM temperature limits. The ADM1033
communicates over an SMBus 2.0 interface. Its LOCATION
input determines which version of SMBus to use, as well as the
SMBus address (in fixed-and-discoverable mode), and the
LOCATION bits in the UDID (in ARP-capable mode).
INTERNAL REGISTERS
Table 4 gives a brief description of the ADM1033’s principal
internal registers. For more detailed information on the
function of each register, refer to .
SERIAL BUS INTERFACE
The ADM1033 communicates with the master via the 2-wire
SMBus 2.0 interface. It supports two SMBus 2.0 versions,
determined by the value of the LOCATION input resistors.
The first version is fully ARP-capable. This means that it
supports address resolution protocol (ARP), allowing the
master to dynamically address the device on power-up. It
responds to ARP commands such as “Prepare to ARP.”
The second SMBus version, fixed-and-discoverable, is
backward-compatible with SMBus 1.0 and 1.1. In this mode, the
ADM1033 powers up with a fixed address, which is determined
by the state of the LOCATION pin on power-up. Note: when
using the ADM1033, addresses 0xC2 and 0xCA should not be
used by any other device on the bus.
LOCATION INPUT
The LOCATION input is a resistor divider input. It has multiple
functions and can specify the following: the SMBus version
(in fixed-and-discoverable or ARP-capable modes); the SMBus
address (in fixed-and-discoverable mode); and the LLL bits
(in UDID in ARP-capable mode).
The voltage of this 8-level input is set by a potential divider. The
voltage on LOCATION is sampled on power-up and digitized
by the on-chip ADC to determine the LOCATION input value.
Because the LOCATION input is sampled only at power-up,
changes made while power is applied have no effect.
VCC
R1
PIN 13
R2
ADM1033
LOCATION
GND
Figure 16. Bootstrapping the LOCATION Input
SMBus 2.0 ARP-CAPABLE MODE
In ARP-capable mode, the ADM1033 supports such features as
address resolution protocol (ARP) and unique device identifier
(UDID). The UDID is a 128-bit message that describes the
ADM1033’s capabilities to the master. The UDID also includes a
vendor-specific ID for functionally equivalent devices.
VCC
ARP
LOCATION = 111 1.5kΩ
ARP
LOCATION = 110 1kΩ
ARP
LOCATION = 101 1kΩ
ARP
LOCATION = 100 1kΩ
FD
ADDRESS = 53h 1kΩ
FD
ADDRESS = 52h 1kΩ
FD
ADDRESS = 51h 1.5kΩ
FD
ADDRESS = 50h
GND
ADM1033 NO. 1
ADM1033 NO. 2
ADM1033 NO. 3
ADM1033 NO. 4
ADM1033 NO. 5
ADM1033 NO. 6
ADM1033 NO. 7
ADM1033 NO. 8
Figure 17. Setting Up Multiple ADM1033 Addresses
In SMBus 2.0 mode, this vendor-specific ID is generated by an
on-chip random number generator. This should enable two
adjacent ADM1033s in the same system to power-up with a
different vendor-specific ID, allowing the master to identify the
two separate ADM1033s and assign a different address to each.
The state of the LOCATION input on power-up is also reflected
in the UDID. This is useful when there are more than one
ADM1033 in the system, so the master knows which one it is
communicating with. The UDID values are listed in Table 6.
The SMBus 2.0 master issues both general and directed ARP
commands. A general command is directed at all ARP devices.
A directed command is targeted at a single device, once an
address has been established. The PEC byte must be used for
ARP commands (refer to Packet Error Checking (PEC)). The
ADM1033 responds to the following commands:
• Prepare to ARP (general)
• Reset device (general and directed)
• Get UDID (general and directed)
• Assign address (general)
Rev. 0 | Page 10 of 40
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