MAX6660EVKIT Maxim Integrated Products, MAX6660EVKIT Datasheet - Page 10

• Manufacturer Part Number: MAX6660EVKIT
• Description: EVAL KIT FOR MAX6660
• Manufacturer: Maxim Integrated Products

Specifications of MAX6660EVKIT

• Sensor Type: Temperature, Fan Controller
• Sensing Range: -40°C ~ 125°C
• Interface: SMBus (2-Wire/I²C)
• Sensitivity: ±1°C
• Voltage - Supply: 3 V ~ 5.5 V
• Embedded: No
• Utilized Ic / Part: MAX6660
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The SMBus interface includes a Timeout, which resets
the interface any time the data or clock line is held low
for more than 35ms, ensuring that the MAX6660 can
never “lock” the bus.
Two registers, at addresses 00h and 01h, store the
measured temperature data from the remote diode. The
data format for the remote-diode temperature is 10 bit
+ sign, with each bit corresponding to 0.125°C, in two’s
complement format (Table 2). Register 01h contains the
sign bit and the first 7 bits. Bits 7, 6, 5 of Register 00h
are the 3LSBs. If the two registers are not read at the
same time, their contents may be the result of two dif-
ferent temperature measurements leading to erroneous
temperature data. For this reason, a parity bit has been
added to the 00h register. Bit 4 of this is zero if the data
in 00h and 01h are from the same temperature conver-
sion and are 1 if they are not. The remaining bits are
“don’t cares.” When reading temperature data, register
01h must be read first.
The MAX6660 provides four alarm threshold registers
that can be programmed with a two’s complement tem-
perature value with each bit corresponding to 1°C. The
registers are T
measured temperature equals or exceeds T
less than T
measured temperature equals or exceeds T
OVERT output is asserted (see Over-Temperature
Output (
vated by the temperature exceeding T
only be deasserted by the temperature dropping below
T
55°C, for T
The MAX6660 has an over-temperature output (OVERT)
that is set when the remote-diode temperature crosses
the limits set in the T
the remote-diode temperature exceeds T
OVERT line clears when the temperature drops below
T
to mask the OVERT output. Typically, the OVERT output
is connected to a power-supply shutdown line to turn
system power off. At power-up, OVERT defaults to
active-low but the polarity can be reversed by setting
bit 5 of the Configuration register.
The OVERT line can be taken active, either by the
MAX6660 or driven by an external source. An external
source can be masked by bit 2 of the Configuration
register. When OVERT is active, the fan loop forces the
fan to full speed and bit 1 of the Status register is set.
Remote-Junction Temperature-Controlled
Fan-Speed Regulator with SMBus Interface
10
HYST
HYST
______________________________________________________________________________________
. The POR state for T
. Bit 1 of the Configuration register can be used
OVERT) section). If ALERT and OVERT are acti-
Remote Temperature Data Register
MAX
LOW
is +100°C, and for T
, an ALERT interrupt is asserted. If the
HIGH
Over-Temperature Output ( OVERT )
, T
Alarm Threshold Registers
MAX
LOW
register. It is always active if
HIGH
, T
MAX
is +127°C, for T
HYST
, and T
is +95°C.
MAX
HYST
HIGH
, they can
MAX
MAX
LOW
. If the
, or is
. The
, the
is -
A continuity fault detector at DXP detects an open cir-
cuit between DXP and DXN. If an open or short circuit
exists, register 01h is loaded with 000 0000.
Additionally, if the fault is an open circuit, bit 2 of the
status byte is set to 1 and the ALERT condition is acti-
vated at the end of the conversion. Immediately after
POR, the Status register indicates that no fault is pre-
sent until the end of the first conversion.
The ALERT interrupt output signal is activated (unless it is
masked by bit 7 in the Configuration register) whenever
the remote-diode’s temperature is below T
T
tion), a shorted diode, or an active OVERT also activates
the ALERT signal. The activation of the ALERT signal sets
the corresponding bits in the Status register. There are two
ways to clear the ALERT: sending the ALERT Response
Address or reading the Status register.
The interrupt does not halt automatic conversions. New
temperature data continues to be available over the
SMBus interface after ALERT is asserted. ALERT is an
active-low open-drain output so that devices can share
a common interrupt line. The interrupt is updated at the
end of each temperature conversion so, after being
cleared, reappears after the next temperature conver-
sion, if the cause of the fault has not been removed.
By setting bit 0 in the Configuration register to 1, the
Status register can only be cleared by sending the
SMBus Alert Response Address (see Alert Response
Address section). Prior to taking corrective action, always
check to ensure that an interrupt is valid by reading the
current temperature. To prevent recurring interrupts, the
MAX6660 asserts ALERT only once per crossing of a
given temperature threshold. To enable a new interrupt,
the value in the limit register that triggered the interrupt
must be rewritten. Other interrupt conditions can be
caused by crossing the opposite temperature threshold,
or a diode fault can still cause an interrupt.
Example: The remote temperature reading crosses
T
interrupt and reads the Alert Response Address, clear-
ing the interrupt. The system may also read the status
byte at this time. If the condition persists, the interrupt
reappears. Finally, the host writes a new value to
T
T
The SMBus Alert Response interrupt pointer provides
quick fault identification for simple slave devices that
lack the complex, expensive logic needed to be a bus
HIGH
HIGH
HIGH
HIGH
. A disconnected remote diode (for continuity detec-
, activating ALERT. The host responds to the
. This enables the device to generate a new
interrupt if the alert condition still exists.
Alert Response Address
Diode Fault Alarm
ALERT Interrupts
LOW
or exceeds