The MAX6657/MAX6658/MAX6659 are precise, two-channel digital temperature sensors. Each accurately measures the temperature of its own die and one remote PN junction, and reports the temperature in digital form on a 2-wire serial interface. The remote junction can be a diode-connected transistor like the low-cost NPN type 2N3904 or 2N3906 PNP type. The remote junction can also be a common-collector PNP, such as a substrate PNP of a microprocessor. 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 MAX6657/MAX6658/MAX6659 can function 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 temperature is represented in extended mode as 10 bits + sign with a resolution of 0.125°C. When the conversion rate is faster than 4Hz, output data is 7 bits + sign with a resolution of 1°C. The MAX6657/MAX6658/MAX6659 also include an SMBus timeout feature to enhance system reliability. Remote accuracy is ±1°C between +60°C and +100°C with no calibration needed. The MAX6657 measures temperatures from 0°C to +125°C and the MAX6658/MAX6659 from -55°C to +125°C. The MAX6659 has the added benefit of being able to select one of three addresses through an address pin.
The MAX6657, MAX6658, and MAX6659 are precise two‑channel digital temperature sensors that measure both the die temperature and a remote PN‑junction temperature. They communicate over a standard 2‑wire SMBus/I²C serial interface and support programmable conversion rates, alarm thresholds, and timeout features. The devices are intended for desktop computers, workstations, notebooks, and servers.
The datasheet provides detailed electrical characteristics, pin configurations, recommended PCB layout, and guidelines for remote‑diode selection. It also describes the ADC operation, noise filtering, standby modes, and SMBus command set, enabling designers to integrate the sensors into thermal management systems with high accuracy and low power consumption.
| Temperature measurement range (MAX6657) | 0 °C to +125 °C |
|---|---|
| Temperature measurement range (MAX6658/MAX6659) | -55 °C to +125 °C |
| Resolution (extended mode) | 0.125 °C (10‑bit + sign) |
| Resolution (legacy mode) | 1 °C (7‑bit + sign) |
| Supply voltage range | 3.0 V to 5.5 V |
| Standby supply current | 3 µA to 10 µA |
| Programmable conversion rate | 0.0625 Hz to 16 Hz |
| Alarm outputs (MAX6657/8) | 2 (ALERT, OVERT1) |
| Alarm outputs (MAX6659) | 3 (ALERT, OVERT1, OVERT2) |
They use a 2‑wire SMBus/I²C compatible serial interface that accepts standard SMBus commands.
The MAX6659 provides three alarm outputs: ALERT, OVERT1, and OVERT2.
In standby mode the devices draw between 3 µA and 10 µA.
The devices are rated for a junction temperature up to +150 °C.