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MAX6662MSA+

P1-P3P4-P6P7-P9
MAX6662
12-Bit + Sign Temperature Sensor with
SPI-Compatible Serial Interface
4 _______________________________________________________________________________________
0
4
2
8
6
10
12
-50 500 100 150
SHUTDOWN CURRENT
VS. TEMPERATURE
MAX6662 toc04
TEMPERATURE (°C)
SHUTDOWN CURRENT (μA)
V
CC
= +5.0V
V
CC
= +3.0V
V
CC
= +3.3V
Typical Operating Characteristics (continued)
(V
CC
= +3V, T
A
= +25°C, unless otherwise noted.)
Pin Description
Detailed Description
The MAX6662 continuously converts its die tempera-
ture into a digital value using its integrated ADC.
Temperature data is updated twice a second. The
resulting data is readable at any time through the SPI-
compatible serial interface.
Figure 1 shows the simplified functional diagram of the
MAX6662. Its internal current sources force 100µA and
10µA currents through a diode (diode-connected tran-
sistor), while the integrating ADC measures the voltage
difference. The difference in voltage corresponds to the
die temperature. The result is stored in the Temperature
register. The control logic unit compares the tempera-
ture and the temperature limit settings stored in the reg-
isters to determine whether a fault condition has
occurred.
Temperature Fault Alert
The ALERT is an open-drain active-low (default, also
programmable active-high) output used to alert the sys-
tem to temperature faults. ALERT can be programmed
to operate in either one of two modes: comparator or
interrupt mode.
Interrupt Mode
In the interrupt mode, the MAX6662 ALERT pin asserts
an alarm for an undertemperature (T
LOW
) fault, as well
as for an overtemperature (T
HIGH
) fault. Once either
fault has occurred, it remains active indefinitely, regard-
less of condition. ALERT is unconditionally deasserted
(even if Temperature is still out of limits) by reading the
temperature register. ALERT only asserts again if the
temperature crosses the hysteresis, thereby corre-
sponding to the fault (T
LOW
or T
HIGH
) that initially set
the ALERT.
PIN NAME FUNCTION
1 SCLK Serial-Clock Input
2 CS Chip Select Input. Set low to enable the serial interface for data input/output.
3 SIO Serial-Data Input/Output. Bidirectional data input and output for serial interface.
4 GND Ground
5 OT Overtemperature Output. Open-drain output requires a pullup resistor to V
CC
.
6 ALERT Alert Output. Open-drain output requires a pullup resistor to V
CC
.
7 NC No Connection. Do not make a connection to this pin.
8V
CC
Supply Voltage Input. Bypass to GND with a 0.1µF capacitor as close to V
CC
as possible.
MAX6662
12-Bit + Sign Temperature Sensor with
SPI-Compatible Serial Interface
_______________________________________________________________________________________ 5
For example: If T
HIGH
is set to 100°C and T
HYST
is set
to 20°C, ALERT does not assert until temperature
exceeds 100°C. If the temperature is then read through
the serial interface, ALERT deasserts. ALERT asserts
again when temperature is less than 80°C (Figure 2).
Comparator Mode
In the comparator mode, ALERT is asserted when tem-
perature exceeds the value in the T
HIGH
register, or is
lower than the value in the T
LOW
register. ALERT
deasserts when temperature is less than T
HIGH
- T
HYST
or greater than T
LOW
+ T
HYST
. Reading the registers
does not deassert ALERT.
For example: If T
HIGH
is set to 100°C and T
LOW
is set
to 80°C, ALERT does not assert until temperature
exceeds 100°C, or is below 80°C. Then, ALERT only
deasserts if temperature is less than T
HIGH
- T
HYST
or
greater than T
LOW
+ T
HYST
.
Overtemperature Alert
OT operates only in comparator mode. The OT pin is
asserted when the temperature exceeds T
MAX
, and
deasserted when the temperature drops below
T
MAX
- T
HYST
. A read operation does not reset OT.
OT is an open-drain active-low (default) output, but can
be programmed to active-high.
TEMPERATURE
OT
SERIAL INTERFACE
V
CC
SIO
SCLK
CONFIGURATION
CS
ALERT
T
LOW
T
HIGH
T
MAX
T
HYST
12 -BIT
+ SIGN
ADC
Figure 1. MAX6662 Simplified Functional Diagram
T
HIGH
- T
HYST
T
HIGH
T
LOW
T
LOW
+ T
HYST
ALERT
TEMPERATURE
LAST INTERRUPT MISSED, BUT
THRESHOLD STILL CHANGES TO T
HIGH
.
** *
*
TEMPERATURE READ
Figure 2. Example of ALERT Operation in Interrupt Mode
MAX6662
12-Bit + Sign Temperature Sensor with
SPI-Compatible Serial Interface
6 _______________________________________________________________________________________
Temperature Fault Queue
The activation of ALERT and OT is subject to the depth
of the fault queue. If the Fault Queue bit in the
Configuration register is enabled, ALERT or OT does
not assert until four consecutive temperature conver-
sions are at fault.
For example: If T
HIGH
is set to 100°C, T
HYST
is set to
20°C, ALERT is set to interrupt mode, and fault queue
is enabled, ALERT does not assert until four consecu-
tive conversions exceed 100°C. If the temperature is
then read through the serial interface, ALERT
deasserts. ALERT asserts again when four consecutive
conversions are less than 80°C.
Shutdown Mode
The MAX6662 features a programmable shutdown
mode. Set the Shutdown bit in the Configuration register
to 1 to shut down. In the shutdown mode, everything is
disabled except the power-on reset (POR) and the seri-
al interface. In the shutdown mode, information stored
in all registers is retained. The Temperature register
retains the temperature from the last conversion result.
Serial Interface Protocol
The serial interface consists of three signal lines: chip
select (CS), bidirectional data line (SIO), and serial
clock (SCLK). Only the master (external) drives CS and
SCLK. Both the master and the MAX6662 drive SIO.
When CS is high, the MAX6662 does not respond to any
activity on clock and data lines. When CS goes low, a
transaction begins. A valid transaction has 24 clock
cycles provided from SCLK after CS goes low—no more
and no fewer. Any communication with more or fewer
than exactly 24 clocks is ignored. Data is clocked in to
the MAX6662 at the rising edge of SCLK when the mas-
ter is writing. Data is clocked out at the falling edge of
SCLK when the master is reading. Both the command
byte and data word are clocked in (or out) with the
most-significant bit (MSB) bit first. The first eight clock
cycles are dedicated to the command byte (1 bit per
cycle). This command byte is input to the MAX6662
through the SIO. Sixteen cycles of data follow. The 16
cycles of data are either driven by the master or by the
MAX6662, depending on the command byte. If the
MAX6662 is driving the SIO, it starts driving at the
falling edge of the eighth clock up until the rising edge
of CS. Data is available on the falling edge of the eighth
clock cycle. Figure 3 depicts a valid serial interface
transaction and Figure 4 is the serial interface timing
diagram.
1234567 8 910 2324
DATA WORD (16 BITS)
CS
SCLK
SIO
COMMAND BYTE (8 BITS)
Figure 3. MAX6662 Serial Interface Operation
t
CSS
t
CSH
t
CSW
t
CH
t
CL
t
TR
t
DS
t
DO
t
F
CS
SCLK
SIO
t
DH
Figure 4. Detailed Serial Interface Timing Diagram
BIT POR DESCRIPTION
15 to 13 0 Reserved. Writing to these bits is ignored.
12 0 Fault Queue bit. Set to 1 to enable queue.
11 0 ALERT polarity bit. Set to 1 for active-high ALERT output. Default is 0 for the ALERT output active-low.
10 0 OT polarity bit. Set to 1 for active-high OT output. Default is 0 for the OT output active-low.
9 0 Interrupt Mode bit. Set to 1 to enable the interrupt mode. Default is 0 for the comparator mode.
8 0 Shutdown bit. Set to 1 to shut down the MAX6662.
7 to 0 0 Reserved. Writing to these bits is ignored.
Table 1. Bit Descriptions of the Configuration Register
P1-P3P4-P6P7-P9

MAX6662MSA+

Mfr. #:
Buy MAX6662MSA+
Manufacturer:
Maxim Integrated
Description:
Board Mount Temperature Sensors 12-Bit + Sign Temperature Sensor
Lifecycle:
New from this manufacturer.
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