MAX6656MEE+ Maxim Integrated Products, MAX6656MEE+ Datasheet - Page 8

• Manufacturer Part Number: MAX6656MEE+
• Description: IC TEMP SENSOR 4CH 16-QSOP
• Manufacturer: Maxim Integrated Products

Specifications of MAX6656MEE+

• Function: Temp Monitoring System (Sensor)
• Topology: ADC, Multiplexer, Register Bank
• Sensor Type: External & Internal
• Sensing Temperature: -55°C ~ 125°C, External Sensor
• Output Type: I²C™/SMBus™
• Output Alarm: Yes
• Output Fan: Yes
• Voltage - Supply: 3 V ~ 5.5 V
• Operating Temperature: -55°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 16-QSOP
• Full Temp Accuracy: +/- 3 C
• Digital Output - Bus Interface: Serial (2-Wire)
• Digital Output - Number Of Bits: 11 bit
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 55 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The temperature data is stored in internal registers
RRTE, RRT2, and RLTS as 7 bits + sign in two’s com-
plement form with each LSB representing 1°C.
Additionally, the 3MSBs of the Extended Temperature
register contain fractional temperature data with
+0.125°C resolution (Tables 2 and 3). The voltage data
is stored in RV0, RV1, RV2, and RV3 as 8 bits in binary
form (Table 4).
OVERT output is an unlatched open-drain output that
behaves as a thermostat for fan control or system shut-
down (Figure 4). This output responds to the current
temperature. If the current temperature is above T
OVERT activates and does not go inactive until the tem-
perature drops below T
A continuity fault detector at DXP detects whether the
remote diode has an open-circuit condition, short-cir-
cuit to GND, or short-circuit DXP-to-DXN condition. At
the beginning of each conversion, the diode fault is
checked, and the Status Byte is updated. This fault
detector is a simple voltage detector; if DXP rises
above V
fault is detected. Note that the diode fault isn’t checked
until a conversion is initiated, so immediately after POR,
the status byte indicates no fault is present, even if the
diode path is broken.
If the remote channel is shorted (DXP to DXN or DXP to
GND), the ADC reads 1111 1111 so as not to trip either
Dual Remote/Local Temperature Sensors and
Four-Channel Voltage Monitors
Figure 4. System Shutdown Application
8
2N3906
INTERFACE
(TO HOST)
_______________________________________________________________________________________
SMBus
SERIAL
CC
+3V TO +5.5V
- 1V (typ) or below V
2200pF
HIGH
.
SMBCLK
SMBDATA
ALERT
DXP2
DXN2
MAX6655
MAX6656
Diode Fault Alarm
DXN
V
CC
OVERT Output
OVERT
ADD0
ADD1
+ 50mV (typ), a
GND
TO SYSTEM
SHUTDOWN
HIGH
,
the T
Similarly, if DXP_ is short circuited to V
reads -1°C for both remote channels, and the ALERT
outputs are activated.
Normally, the ALERT interrupt output signal is latched
and can be cleared either by responding to the Alert
Response Address or by reading the Status register.
Interrupts are generated in response to T
T
remote diode is faulted. The interrupt does not halt auto-
matic conversions; new temperature data continues to
be available over the SMBus interface after ALERT is
asserted. The interrupt output pin is open-drain so multi-
ple devices can share a common interrupt line.
The interface responds to the SMBus Alert Response
address, an interrupt pointer return-address feature
(see the Alert Response Address section). Before tak-
ing corrective action, always check to ensure that an
interrupt is valid by reading the current temperature.
The alert activates only once per crossing of a given
temperature threshold to prevent any reentrant inter-
rupts. To enable a new interrupt, rewrite the value of the
violated temperature threshold.
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 master.
Upon receiving an ALERT interrupt signal, the host mas-
ter can broadcast a Receive Byte transmission to the
Alert Response slave address (0001100). Any slave
device that generated an interrupt then attempts to identi-
fy itself by putting its own address on the bus (Table 5).
The Alert Response can activate several different slave
devices simultaneously, similar to the I
If more than one slave attempts to respond, bus arbitra-
tion rules apply, and the device with the lower address
code wins. The losing device does not generate an
acknowledgment and continues to hold the ALERT line
low until serviced (implies that the host interrupt input is
level sensitive). The alert is cleared after the slave
address is returned to the host.
The 8-bit Command Byte register (Table 6) is the mas-
ter index that points to the other registers within the
MAX6655/MAX6656. The register’s POR state is 0000
0000, so a Receive Byte transmission (a protocol that
lacks the Command Byte) that occurs immediately after
POR returns the current internal temperature data.
LOW
, V
HIGH
HIGH
or T
and V
LOW
LOW
alarms at their POR settings.
Command Byte Functions
Alert Response Address
comparisons, and when the
Alert Interrupts
2
C General Call.
CC
, the ADC
HIGH
and