MAXIM Manuals

The MAX6680/MAX6681 are precise, two-channel digital thermometers that accurately measure the temperature of their own die and one remote PN junction and report the temperature on a 2-wire serial interface. The remote junction can be a diode-connected transistor like the low-cost NPN type 2N3904 or PNP type 2N3906. The remote junction can also be a common-collector PNP, such as a substrate PNP of a microprocessor. The MAX6680/MAX6681 include pin-programmable default temperature thresholds for the OVERT output, which provides fail-safe clock throttling or system shut- down. In addition, the devices are pin programmable to select whether the OVERT output responds to either the local, remote, or both temperatures. The 2-wire serial interface accepts standard System Management Bus (SMBus)™ commands such as Write Byte, Read Byte, Send Byte, and Receive Byte to read the temperature data and program the alarm thresholds and conversion rate. The MAX6680/MAX6681 can func- tion autonomously with a programmable conversion rate, which allows the control of supply current and temperature update rate to match system needs. For conversion rates of 4Hz or less, the remote sensor tem- perature can be represented in extended mode as 10 bits + sign with a resolution of 0.125°C. When the con- version rate is 8Hz, output data is 7 bits + sign with a resolution of 1°C. The MAX6680/MAX6681 also include an SMBus timeout feature to enhance system reliability. The MAX6681 i

The MAX8865 and MAX8866 are dual low-dropout linear regulators that operate from a +2.5V to +5.5V input range and deliver up to 100mA. These devices are ideal for battery-operated portable equipment such as cellular phones, cordless phones, and modems. They feature Dual Mode™ operation, with preset output voltages of 3.15V for the “T” versions, 2.84V for the “S” versions, or 2.80V for the “R” versions, or adjustable output voltages using external resistor dividers. Other features include independent low-power shutdown, short-circuit protection, thermal shutdown protection, and reverse battery protection. The MAX8866 also includes an auto-discharge function, which actively discharges the selected output voltage to ground when the device is placed in shutdown mode. Both devices come in a miniature 8-pin µMAX package.

The MAX6655/MAX6656 are precise voltage and temperature monitors. The digital thermometer reports the temperature of two remote sensors and its own die temperature. The remote sensors are diode-connected transistors—typically a low-cost, easily mounted 2N3906 PNP type—that replace conventional thermistors or thermocouples. Remote accuracy is ±1°C for multiple transistor manufacturers with no calibration necessary. The remote channels can also measure the die temperature of other ICs, such as microprocessors, that contain a substrate-connected PNP with its collector grounded and its base and emitter available for temperature-sensing purposes. The temperature is digitized with 11-bit resolution. The MAX6655/MAX6656 also measure their own supply voltage and three external voltages with 8-bit resolution. Each voltage input’s sensitivity is set to give approximately 3/4-scale output code when the input voltage is at its nominal value. The MAX6655 operates at +5V supply and its second voltage monitor is 3.3V. The MAX6656 operates on a +3.3V supply and its second voltage monitor is 5V. The 2-wire serial interface accepts standard SMBus™ Write Byte, Read Byte, Send Byte, and Receive Byte commands to program the alarm thresholds and to read data. The MAX6655/MAX6656 also provide SMBus alert response and timeout functions. The MAX6655/MAX6656 measure automatically and autonomously, with the conversion rate programmable. The adjustable rate allows the u

The MAX6697 precision multichannel temperature sensor monitors its own temperature and the temperatures of up to six external diode-connected transistors. All temperature channels have programmable alert thresholds. Channels 1, 4, 5, and 6 also have programmable overtemperature thresholds. When the measured temperature of a channel exceeds the respective threshold, a status bit is set in one of the status registers. Two open-drain outputs, OVERT and ALERT, assert corresponding to these bits in the status register. The 2-wire serial interface supports the standard system management bus (SMBus™) protocols: write byte, read byte, send byte, and receive byte for reading the temperature data and programming the alarm thresholds. The MAX6697 is specified for an operating temperature range of -40°C to +125°C and is available in 20-pin QSOP and 20-pin TSSOP packages.

The MAX6684 is an integrated fan-failure detector that detects when a fan exhibits excessive underspeed or a locked rotor. This device is especially well suited for critical systems where no fan control, or simple on/off control is desired. The MAX6684 detects fan failure by evaluating fluctuations in current at the low side of the fan; no tachometer signal is necessary. The output of the device, FAIL, is an active-low, open-drain alarm. The MAX6684 can also be used to switch the fan on or off, based on the state of a logic-level input, OFF. This device can be used with fans rated at up to 24V and 250mA. The MAX6684 is available in an 8-pin SO package, and is specified for operation from -40°C to +85°C.

MAX6675 is a K-type thermocouple digital converter produced by Maxim Integrated Products. It features cold-end compensation, 12-bit resolution, SPI interface, 0.25 °C resolution and other features.

The MAX6648/MAX6692 are precise, two-channel digital temperature sensors. They accurately measure the temperature of their own die and a remote PN junction, and report the temperature in digital form using a 2-wire serial interface. The remote PN junction is typically the emitter-base junction of a common-collector PNP on a CPU, FPGA, or ASIC.

MAX6695/MAX6696 are precision dual remote and local digital temperature sensors. These devices can accurately measure temperatures and report the measurements digitally via a 2-wire serial interface. They have programmable conversion rates and alarm thresholds, making them suitable for use in laptops, desktop computers, servers, workstations, and test and measurement equipment.

The MAX6695/MAX6696 are precise, dual-remote, and local digital temperature sensors. They accurately measure the temperature of their own die and two remote diode-connected transistors, and report the temperature in digital form on a 2-wire serial interface. The MAX6695/MAX6696 can function autonomously with a programmable conversion rate, which allows control of supply current and temperature update rate to match system needs. They measure temperatures from -40°C to +125°C, with a remote temperature sensing accuracy of ±1.5°C between +60°C and +100°C, with no calibration needed. The MAX6695/MAX6696 also include an SMBus timeout feature and two overtemperature limit indicators (OT1 and OT2).

MAX6646/MAX6647/MAX6649 are precise, two-channel digital temperature sensors.

The DS1626 and DS1726 digital thermometers/thermostats provide temperature measurements and stand-alone thermostat capability over a -55°C to +125°C range. The DS1626 offers ±0.5°C accuracy from 0°C to +70°C and the DS1726 has ±1°C accuracy from -10°C to +85°C. The resolution of the measured temperature is user selectable from 9 to 12 bits. Communication with the DS1626 and DS1726 is achieved through a 3-wire serial bus. The DS1626 and DS1726 offer thermostatic functionality with three dedicated thermostat outputs (THIGH, TLOW, and TCOM), and overtemperature (TH) and undertemperature (TL) user-programmable thresholds stored in on-chip EEPROM. For stand-alone thermostat operation, TH and TL can be programmed prior to installation, and the DS1626/DS1726 can be configured to automatically begin taking temperature measurements at power-up. Table 1 summarizes the user-accessible registers. Figure 1 shows a functional diagram.

MAX6685/MAX6686 are dual-output temperature switches that use an external diode-connected transistor as a sens- ing element

The MAX253 is a monolithic oscillator/power-driver specifically designed to provide isolated power for an isolated RS-485 or RS-232 data interface. The device drives a center-tapped transformer primary from a 5V or 3.3V DC power supply. The secondary can be wound to provide any isolated voltage needed at power levels up to 1W. The MAX253 consists of a CMOS oscillator driving a pair of N-channel power switches. The oscillator runs at double the output frequency, driving a toggle flip-flop to ensure 50% duty cycle to each of the switches. Internal delays are arranged to ensure break-before-make action between the two switches. The SD pin puts the entire device into a low-power shutdown state, disabling both the power switches and oscillator.

The MXB7846 is a 4-wire touch-screen controller that uses an internal reference and temperature sensor. It contains a 12-bit sampling analog-to-digital converter (ADC) with its synchronous serial interface and low on-resistance switches for driving resistive touch screens. The device has an on-chip temperature sensor, a battery-monitoring channel, and has the ability to perform touch-pressure measurements without external components. The device has one auxiliary ADC input. All analog inputs are fully ESD protected, eliminating the need for external TransZorb™ devices. The MXB7846 guarantees to operate with a supply voltage down to +2.375V when used with an external reference or +2.7V with an internal reference. In shut-down mode, the typical power consumption is reduced to under 0.5µW, while the typical power consumption at 125ksps throughput and a +2.7V supply is 650µW. Low-power operation makes the MXB7846 ideal for battery-operated systems, such as personal digital assistants.

The MAX6612 is a low-power precision analog output temperature sensor from Texas Instruments. It has high accuracy and stability, and its operating temperature range is -10°C to +125°C.