MAXIM Manuals

The MAX6575L/H is a low-cost, low-current temperature sensor with a single-wire digital interface.

The MAX6640 monitors its own temperature and one external diode-connected transistor or the temperatures of two external diode-connected transistors, typically available in CPUs, FPGAs, or GPUs. The 2-wire serial interface accepts standard System Management Bus (SMBusTM) write byte, read byte, send byte, and receive byte commands to read the temperature data and program the alarm thresholds. Temperature data can be read at any time over the SMBus, and three programmable alarm outputs can be used to generate interrupts, throttle signals, or overtemperature shutdown signals. The temperature data is also used by the internal dual PWM fan-speed controller to adjust the speed of up to two cooling fans, thereby minimizing noise when the system is running cool, but providing maximum cooling when power dissipation increases. Speed control is accomplished by tachometer feedback from the fan, so that the speed of the fan is controlled, not just the PWM duty cycle. Accuracy of speed measurement is ±4%. The MAX6640 is available in 16-pin QSOP and 16-pin TQFN 5mm x 5mm packages. It operates from 3.0V to 3.6V and consumes just 500μA of supply current.

The MAX6640 is a 5mm x 5mm QFN package temperature sensor, supports over temperature alarm and current detection functions, supports PWM output

The MAX6665 is a fully integrated thermal switch with an internal power transistor for driving a cooling fan rated up to 24V and 250mA. When the MAX6665’s temperature rises above a factory-programmed threshold, the FANOUT pin becomes active and powers the fan. The MAX6665 is available with factory-programmed fan activation threshold temperatures from +40°C to +70°C in 5°C increments. Accuracy of the fan activation trip point is ±1°C (typ) and ±3°C (max). The trip point’s hysteresis is pin selectable to 1°C, 4°C, or 8°C. Two open-drain logic outputs indicate overtemperature conditions: WARN is activated when the temperature is 15°C above the fan activation threshold, and OT is activated when the temperature is 30°C above the threshold. These features can be used to safely power down systems that are overheated. The MAX6665 operates from a +2.7V to +5.5V power supply, and the associated fan can be powered from 4.5V to 24V. It is available in an 8-pin SO package and operates from -40°C to +125°C.

MAX6633/MAX6634/MAX6635 is a temperature sensor, programmable overtemperature alarm and SMBus™/I2C™-compatible serial interface integrated by MAXIM.

The MAX6576/MAX6577 are low-cost, low-current temperature sensors with a single-wire output. The MAX6576 converts the ambient temperature into a square wave with a period proportional to absolute temperature (°K). The MAX6577 converts the ambient temperature into a square wave with a frequency proportional to absolute temperature. The MAX6576 offers accuracy of ±3°C at +25°C, ±4.5°C at +85°C, and ±5°C at +125°C. The MAX6577 offers accuracy of ±3°C at +25°C, ±3.5°C at +85°C, and ±4.5°C at +125°C. Both devices feature a single-wire output that minimizes the number of pins necessary to interface with a microprocessor. The period/frequency range of the output square wave can be selected by hard-wiring the two time-select pins (TS0, TS1) to either VDD or GND. The MAX6576/MAX6577 are available in space-saving 6-pin SOT23 packages. Applications include critical µP and µC temperature monitoring, portable battery-powered equipment, cell phones, battery packs, hard drives/tape drives, networking and telecom equipment, medical equipment, and automotive.

MAX6642 is a precision dual-channel digital temperature sensor from TI that accurately measures the temperature of its own die and a remote PN junction and reports the temperature data over a 2-wire serial interface

The MAX6627/MAX6628 precise digital temperature sensors report the temperature of a remote sensor. The remote sensor is a diode-connected transistor, typically a low-cost, easily mounted 2N3904 NPN type that replaces conventional thermistors or thermocouples. The MAX6627/MAX6628 can also measure the die temperature of other ICs, such as microprocessors (µPs) or microcontrollers (µCs) that contain an on-chip, diode-connected transistor. Remote accuracy is ±1°C when the temperature of the remote diode is between 0°C and +125°C and the temperature of the MAX6627/MAX6628 is +30°C. The temperature is converted to a 12-bit + sign word with 0.0625°C resolution. The architecture of the device is capable of interpreting data as high as +145°C from the remote sensor. The MAX6627/MAX6628 temperature should never exceed +125°C. These sensors are 3-wire serial interface SPI compatible, allowing the MAX6627/MAX6628 to be readily connected to a variety of µCs. The MAX6627/MAX6628 are read-only devices, simplifying their use in systems where only temperature data is required. Two conversion rates are available, one that continuously converts data every 0.5s (MAX6627), and one that converts data every 8s (MAX6628). The slower version provides minimal power consumption under all operating conditions (30µA, typ). Either device can be read at any time and provide the data from the last conversion.

The MAX6674 is a cold-junction-compensation thermocouple-to-digital converter that performs cold-junction compensation and digitizes the signal from a type-K thermocouple. The data is output in a 10-bit resolution, SPI-compatible, read-only format. This converter resolves temperatures to 0.125°C, allows readings as high as +128°C, and exhibits thermocouple accuracy of ±2°C for temperatures ranging from 0°C to +125°C. The MAX6674 is available in a small, 8-pin SO package.

The MAX845 provides an isolated power supply small enough to fit in thin PCMCIA cards and space-sensitive applications. It drives a low-profile center-tapped trans- former primary from a 5V or 3.3V DC power supply. The secondary can be wound to provide any isolated posi- tive or negative voltage at powers up to 750mW. The MAX845 consists of an oscillator followed by a tog- gle flip-flop. The flip-flop generates two 50% duty-cycle square waves, which are complementary at half the oscillator frequency (450kHz, min). These two signals drive the ground-referenced N-channel power switch- es. Internal circuitry ensures break-before-make action between the two switches. A low-power shutdown disables both the switches and the oscillator, reducing power consumption. An evalua- tion kit (MAX845EVKIT-MM) is available to evaluate low- profile 5V 40mA and 5V 100mA applications.

The MAX6639 is a temperature monitor that monitors its own temperature and the temperature of an external diode-connected transistor or two external diode-connected transistors typically found in CPUs, FPGAs, or GPUs. It features a 2-wire serial interface that accepts SMBus commands for reading temperature data and setting alarm thresholds. Temperature data can be read at any time over the SMBus, and three programmable alarm outputs can be used for generating interrupts, throttle signals, or overtemperature shutdown signals. The temperature data is also used by the internal dual-PWM fan-speed controller to adjust the speed of up to two cooling fans, providing minimum noise when the system is running cool and maximum cooling when power dissipation increases. Speed control is achieved through tachometer feedback from the fan, ensuring control of the fan speed rather than just the PWM duty cycle. The speed measurement accuracy is ±4%. The MAX6639 is available in 16-pin QSOP and 16-pin thin QFN 5mm x 5mm packages. It operates from 3.0V to 3.6V and consumes just 500µA of supply current. It is suitable for applications such as desktop computers, notebook computers, projectors, servers, and networking equipment.

DS7505 is a low voltage (1.7V to 3.7V) digital thermometer and thermostat that provides 9-, 10-, 11-, or 12-bit digital temperature readings over a -55°C to +125°C range with ±0.5°C accuracy over a -0°C to +70°C range. A 9-bit resolution mode is software compatible with the LM75. Communication with the DS7505 is achieved through a simple 2-wire serial interface. Three address pins allow up to eight DS7505 devices to operate on the same 2-wire bus, which greatly simplifies distributed temperature-sensing applications. The DS7505 thermostat has a dedicated open-drain output (O.S.) and programmable fault tolerance, which allows the user to define the number of consecutive error conditions that must occur before O.S. is activated. There are two thermostatic operating modes that control thermostat operation based on user-defined trip points (TOS and THYST) that are stored in EEPROM registers.

The MAX6678 monitors its own temperature and the temperatures of two external diode-connected transistors, which typically reside on the die of a CPU or other integrated circuit. The device reports temperature values in digital form using a 2-wire serial interface. The MAX6678 provides a programmable alarm output to generate interrupts, throttle signals, or overtemperature shutdown signals. The 2-wire serial interface accepts standard System Management Bus (SMBus)™ write byte, read byte, send byte, and receive byte commands to read the temperature data and program the alarm thresholds. The temperature data controls a PWM output signal to adjust the speed of a cooling fan, thereby minimizing noise when the system is running cool, but providing maximum cooling when power dissipation increases. Five GPIO pins provide additional flexibility. The GPIO power-up states are set by connecting the GPIO preset inputs to ground or VCC. The MAX6678 is available in a 20-pin QSOP package and a 5mm x 5mm thin QFN package. It operates from 3.0V to 5.5V and consumes just 500µA of supply current.