General Description
The MAX6662 is a 12-bit + sign temperature sensor
combined with a programmable overtemperature alarm
and a 3-wire (SPI™-compatible) serial interface in a single package. It converts its die temperature into digital
values using an internal analog-to-digital converter
(ADC). The temperature data is stored in a temperature
register as a 13-bit word, which allows 0.0625°C resolution. The temperature data is readable at any time
through the serial interface. The operating temperature
range is -55°C to +150°C.
The MAX6662 provides two programmable watchdog
interrupt outputs. ALERT is used for lower temperature
warning functions, while OT is used for higher temperature-critical functions, such as power-supply shutdown.
The MAX6662 features a shutdown mode that saves
power by disabling everything except the serial interface. The temperature sensor is available in an 8-pin SO
package.
Applications
HVAC
Refrigeration
Automotive
Test Equipment
Features
♦ 12-Bit + Sign, 0.0625°C Resolution
♦ Accuracy
±1°C max (+30°C to +50°C)
±1.6°C max (0°C to +70°C)
±2.5°C max (-20°C to +85°C)
±2.5 typ (+150°C)
♦ Extended Temperature Measurement Range
-55°C to +150°C
♦ Low Average Supply Current, 125µA (typ)
♦ Shutdown Mode to Minimize Power Consumption
in Portable Applications
♦ Two Programmable Temperature Fault Outputs
♦ Switchable Fault Queue to Eliminate False
Tripping in Noisy Environments
MAX6662
12-Bit + Sign Temperature Sensor with
SPI-Compatible Serial Interface
________________________________________________________________ Maxim Integrated Products 1
Pin Configuration
Ordering Information
10kΩ
10kΩ
0.1µF
V
CC
OT
ALERT
SIO
SCLK
CS
SYSTEM
CONTROLLER
VCC= +3V TO +5.5V
HEAT
SOURCES
MAX6662
Typical Operating Circuit
19-2121; Rev 0; 7/01
SPI is a trademark of Motorola, Inc.
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
PART TEMP. RANGE PIN-PACKAGE
MAX6662MSA -55°C to +150°C 8 SO
TOP VIEW
SCLK
1
2
3
SIO
4
87V
CC
MAX6662
SO
NCCS
ALERT
6
OTGND
5
MAX6662
12-Bit + Sign Temperature Sensor with
SPI-Compatible Serial Interface
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VCC= +3V to +5.5V, TA= -55°C to +125°C, unless otherwise noted. Typical values are at TA= +25°C and VCC= +3.3V.)
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
All Voltages Are Referenced to GND
V
CC
...........................................................................-0.3V to +6V
ALERT, OT................................................................-0.3V to +6V
SIO, SCLK, CS............................................-0.3V to (V
CC
+ 0.3V)
SIO Current .......................................................-10mA to +50mA
Continuous Current into Any Pin (except NC)….................10mA
Continuous Power Dissipation (T
A
= +70°C)
8-Pin SO (derate 5.9mW/°C above +70°C)..................471mW
Operating Temperature Range (Note 1) ..........-55°C to +150°C
Junction Temperature......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Note 1: The MAX6662 is not recommended to operate above +125°C for an extended period of time.
TEMPERATURE TO DIGITAL-CONVERTER CHARACTERISTICS
Accuracy
Power-Supply Rejection Ratio PSRR 0.2 0.5 °C/V
Resolution 0.0625 °C
Supply Voltage Range V
Average Operating Current
Peak Operating Current (Note 2)
Shutdown Supply Current
Power-On-Reset Threshold V
Power-On-Reset Threshold
Hysteresis
Conversion Time t
Temperature Update Frequency 2Hz
SERIAL INTERFACE (SIO, SCLK, CS, ALERT, OT)
Input Low Voltage V
Input High Voltage V
Input/Output Leakage Current I
Input Capacitance C
Output Low Sink Current I
Output High Voltage V
Output Low VoltageV
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
+30°C ≤ TA≤ +50°C, VCC = +3.3V -1.0 ±0.4 +1.0
0°C ≤ TA≤ +70°C, VCC = +3.3V -1.6 ±0.7 +1.6
-20°C ≤ TA≤ +85°C, VCC = +3.3V -2.5 ±1.0 +2.5
-40°C ≤ TA≤ +100°C, VCC= +3.3V -3.0 ±1.2 +3.0
-55°C ≤ TA≤ +125°C, VCC= +3.3V -4.0 ±1.5 +4.0
T
≤ +150°C, VCC = +3.3V ±2.5
A
CC
VCC = +5.5V 150
= +3.0V 125
V
CC
VCC = +5.5V 300 600
= +3.0V 300 500
V
CC
VCC = +5.5V 8 22
V
= +3.0V 4 15
CC
POR
CONV
IL
IH
LEAK
OL
OH
OL
VIN = GND or V
in
ALERT, OT, VOL = 0.6V 3 mA
I
= 1.6mA source V CC- 0.4 V
SIO
I
= 1.6mA sink 0.4 V
SIO
CC
3.0 5.5 V
2.0 2.5 V
90 mV
0.25 s
0.8 V
0.7 V
CC
-5 +5 µA
5pF
°C
µA
µA
µA
V
MAX6662
12-Bit + Sign Temperature Sensor with
SPI-Compatible Serial Interface
_______________________________________________________________________________________ 3
Typical Operating Characteristics
(VCC= +3V, TA= +25°C, unless otherwise noted.)
ELECTRICAL CHARACTERISTICS (continued)
(VCC= +3V to +5.5V, TA= -55°C to +125°C, unless otherwise noted. Typical values are at TA= +25°C and VCC= +3.3V.)
Note 2: Peak operating current measured during conversion.
SERIAL INTERFACE TIMING
Serial Clock Frequency f
SCLK High Pulse Width t
SCLK Low Pulse Width t
CS High Pulse Width t
SCLK Fall to Output Data Valid t
CS Fall to SCLK Rise t
CS Rise to Output Disable t
CS to SCLK Hold Time t
SIO to SCLK Setup Time t
SIO to SCLK Hold Time t
Output Fall Time t
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
SCLK
CH
CL
CSW
DO
CSS
TR
CSH
DS
DH
F
200 ns
200 ns
200 ns
C
= 100pF 100 ns
LOAD
100 ns
C
= 100pF 100 ns
LOAD
0ns
100 ns
0ns
10 ns
2.5 MHz
3
2
1
0
-1
TEMPERATURE ERROR (°C)
-2
-3
-50 3010-30 -10 50 70 90 110 130 150
TEMPERATURE ERROR
VS. TEMPERATURE
VCC = +3.0V
VCC = +5.0V
TEMPERATURE (°C)
VCC = +3.3V
TEMPERATURE ERROR DISTRIBTUTION
90
NOTE: DEVICES
80
TRIMMED AT
T
MAX6662 toc01
PERCENTAGE OF SAMPLES (%)
= +30°C
A
70
60
50
40
30
20
10
0
-0.45-0.35 -0.25-0.15 0.05 0.15 0.25 0.35 0.45
200 SAMPLES
= +30°C
T
A
TEMPERATURE ERROR (°C)
SUPPLY CURRENT VS. TEMPERATURE
200
AVERAGE OVER 2
MAX6662 toc02
180
VCC = +5.0V
160
140
SUPPLY CURRENT (µA)
120
VCC = +3.0V
100
-50 500 100 150
TEMPERATURE (°C)
VCC = +3.3V
MAX6662 toc03
MAX6662
12-Bit + Sign Temperature Sensor with
SPI-Compatible Serial Interface
4 _______________________________________________________________________________________
Typical Operating Characteristics (continued)
(VCC= +3V, TA= +25°C, unless otherwise noted.)
Pin Description
Detailed Description
The MAX6662 continuously converts its die temperature 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 SPIcompatible 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 transistor), 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 temperature and the temperature limit settings stored in the registers 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 system 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, regardless 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 corresponding to the fault (T
LOW
or T
HIGH
) that initially set
the ALERT.
SHUTDOWN CURRENT
VS. TEMPERATURE
12
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 VCC.
6 ALERT Alert Output. Open-drain output requires a pullup resistor to VCC.
7 NC No Connection. Do not make a connection to this pin.
8VCCSupply Voltage Input. Bypass to GND with a 0.1µF capacitor as close to VCC as possible.
10
VCC = +5.0V
8
6
4
SHUTDOWN CURRENT (µA)
2
0
-50 500 100 150
VCC = +3.3V
VCC = +3.0V
TEMPERATURE (°C)
MAX6662 toc04
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 temperature 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.
Figure 1. MAX6662 Simplified Functional Diagram
Figure 2. Example of
ALERT
Operation in Interrupt Mode
V
CC
OT
12 -BIT
+ SIGN
ADC
ALERT
TEMPERATURE
SIO
SCLK
CS
T
LOWTHIGHTMAXTHYST
SERIAL INTERFACE
CONFIGURATION
T
HIGH
T
- T
HIGH
HYST
T
+ T
LOW
HYST
T
LOW
ALERT
* TEMPERATURE READ
TEMPERATURE
** *
LAST INTERRUPT MISSED, BUT
THRESHOLD STILL CHANGES TO T
HIGH
.
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 conversions 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 consecutive 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 serial 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 master 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.
Figure 3. MAX6662 Serial Interface Operation
Figure 4. Detailed Serial Interface Timing Diagram
Table 1. Bit Descriptions of the Configuration Register
CS
SCLK
SIO
1234567 8 910 2324
COMMAND BYTE (8 BITS)
DATA WORD (16 BITS)
t
CSW
t
TR
t
t
DH
F
SCLK
SIO
CS
t
t
CSS
t
CH
t
DS
t
DO
CSH
t
CL
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.
MAX6662
12-Bit + Sign Temperature Sensor with
SPI-Compatible Serial Interface
_______________________________________________________________________________________ 7
The first bit of the command byte is always high to signify a Start, and the second bit is an R/W bit, high for
read and low for write. There are a total of 11 valid
commands. The temperature conversion runs continuously and asynchronously from the serial interface.
When the Temperature register is read, any conversion
in progress is aborted and the data output is from the
previous conversion. A new conversion is started each
time the serial interface is accessed.
MAX6662 Registers
The MAX6662 has six registers: Temperature, Configuration, T
HYST
, T
MAX
, T
LOW
, and T
HIGH
registers. They are
all 16 bits (Figure 5). The Temperature register is read
only; all other registers can be read from or written to.
Temperature Register
The MSB of the Temperature register is the sign bit. The
next 12 bits are temperature data. The digital temperature data for the most recent temperature conversion is
Figure 5. Bit Assignment for the MAX6662 Registers
Table 2. Command Codes for the
Temperature Limit Registers
COMMAND DESCRIPTION
C1h Temperature register read
C3h Configuration register read
C5h T
C7h T
C9h T
CBh T
83h Configuration register write
85h T
87h T
89h T
8Bh T
15
Label
POR
State
Sign
Bit
0000000000000000
HYST
MAX
LOW
HIGH
HYST
MAX
LOW
HIGH
14
Data
MSB
register read
register read
register read
register read
register write
register write
register write
register write
TEMPERATURE REGISTER (COMMAND = C1H)
13 12 11 10 9 8 7 6 5 4 3
1
Data
LSB
T
OVER
Flag
2
T
HIGH
Flag
T
LOW
Flag
0
CONFIGURATION REGISTER (COMMAND = C3H FOR READING; COMMAND = 83H FOR WRITING)
15*14*13
Label
POR
State
Label
POR
State
* Reserved (not used). Writing to this bit is ignored.
** T
** T
** T
** T
0 0 0 0 0 0 0 0 00000000
TEMPERATURE LIMIT REGISTERS (T
15
Sign14Data
MSB
register: 0000 0001 0000 0000b (2°C)
HYST
register: 0010 1000 0000 0000b (+80°C)
MAX
register: 0000 0101 0000 0000b (+10°C)
LOW
register: 0010 0000 0000 0000b (+64°C)
HIGH
12
*
Fault
Queue
13 12 11 10 9 8 7
11
ALERT
Polarity
10
OT
Polarity
9
Interrupt
Mode
, T
HYST
Data
**
Shutdown
MAX
LSB
8
Mode
, T
LOW
6
*
7*6*5*4*3*2*1*0
, T
) (TABLE 2)
HIGH
5
4
3
2
1
*
*
*
*
*
*
0
*
stored in the Temperature register and is in °C, using a
two’s-complement format with 1LSB corresponding to
0.0625°C (Table 3). The three least-significant bits (LSBs)
are temperature status (flag) bits. The Temperature register is read only. Set the command byte to C1h for reading
the Temperature register.
Configuration Register
The Configuration register uses only 5 bits, bits 8 to 12.
Table 1 describes its function. Bit 8 is the shutdown bit
and should be set to 1 to shut down the entire
MAX6662 except the serial interface and POR. Bit 12 is
the fault queue bit. When the Fault Queue bit is 1, the
ALERT and OT outputs are asserted if four consecutive
temperature faults occurred. The Configuration register
can be read or written to. Writing to unused bits is
ignored. Set the command byte to C3h for reading from
this register; set the command byte to 83h for writing to
this register.
Temperature-Limit Registers
The High-Temperature (T
HIGH
), Low-Temperature
(T
LOW
), and the Hysteresis (T
HYST
) registers set the
temperature limit for triggering the ALERT (Figure 1).
The Maximum-Temperature (T
MAX
) and Hysteresis reg-
isters set the temperature threshold for the OT output.
These temperature-limit registers use the 9MSB bits
(8 bits + sign) for setting temperature values in two’s
complement format with 1°C resolution. The 7LSBs are
ignored. These registers can be read or written to.
Table 2 shows the command bytes for reading and
writing to these registers.
Applications Information
The MAX6662 supply current is typically 125µA when
the serial interface is active. When driving high-impedance loads, the devices dissipate negligible power;
therefore, the die temperature is essentially the same
as the package temperature. The key to accurate temperature monitoring is good thermal contact between
the MAX6662 package and the monitored device or circuit. Heat flows in and out of plastic packages primarily
through the leads. Short, wide copper traces leading to
the temperature monitor ensure that heat transfers
quickly and reliably. The rise in die temperature due to
self-heating is given by the following formula:
∆TJ= P
DISSIPATION
x θ
JA
where P
DISSIPATION
is the power dissipated by the
MAX6662, and θJAis the package’s thermal resistance.
The typical thermal resistance is +170°C/W for the
8-pin SO package. To limit the effects of self-heating,
minimize the output currents. For example, if the
MAX6662 sinks 4mA with the maximum ALERT voltage
specification of 0.8V, an additional 3.2mW of power is
dissipated within the IC. This corresponds to a 0.54°C
rise in the die temperature.
Chip Information
TRANSISTOR COUNT: Bipolar: 182
MOS: 10177
PROCESS: BiCMOS
MAX6662
12-Bit + Sign Temperature Sensor with
SPI-Compatible Serial Interface
8 _______________________________________________________________________________________
Table 3. Output Code vs. Temperature
TEMPERATURE (°C) BINARY CODE
+150.0000 0100 1011 0000 0xxx
+125.0000 0011 1110 1000 0xxx
+25.0000 0000 1100 1000 0xxx
+0.0625 0000 0000 0000 1xxx
0.0000 0000 0000 0000 0xxx
-0.0625 1111 1111 1111 1xxx
-25.0000 1111 0011 0111 0xxx
-55.0000 1111 1100 0111 0xxx
MAX6662
12-Bit + Sign Temperature Sensor with
SPI-Compatible Serial Interface
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________ 9
© 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
Package Information
SOICN.EPS
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