Datasheet MAX6627 (Maxim) - 6

link to page 6 link to page 6 link to page 7 MAX6627/MAX6628 Remote ±1°C Accurate Digital Temperature Sensors with SPI-Compatible Serial Interface
Detailed Description
taking CS low, any conversion in progress is stopped, The MAX6627/MAX6628 remote digital thermometers and the rising-edge of CS always starts a fresh report the temperature of a remote sensor. The remote conversion and resets the interface. This permits sensor is a diode-connected transistor—typically, a triggering a con-version at any time so that the power low-cost, easily mounted 2N3904 NPN type—that consumption of the MAX6627 can be overcome, if replaces conventional thermistors or thermocouples. needed. Both devices operate with input voltages between These devices can also measure the die temperature of +3.0V and +5.5V and are specified between -55°C and other ICs, such as µPs or µCs, that contain an on-chip, +125°C. The MAX6627/MAX6628 come in space-saving diode-connected transistor. 8-pin SOT23 and TDFN packages. Remote accuracy is ±1°C when the temperature of
ADC Conversion Sequence
the remote diode is between 0°C and +125°C and the The device powers up as a free-running data converter temperature of the MAX6627/MAX6628 is +30°C. Data (Figure 1). The CS pin can be used for conversion is available as a 12-bit + sign word with 0.0625°C control. The rising-edge of CS resets the interface and resolution. The operating range of the device extends starts a conversion. The falling-edge of CS stops any from -55°C to +125°C, although the architecture of the conversion in progress, overriding the latency of the part. device is capable of interpreting data up to +145°C. The Temperature data from the previous completed conversion device itself should never exceed +125°C. is available for read (Table 1 and Table 2). It is required The devices are designed to work in conjunction with to maintain CS high for a minimum of 320ms to complete an external µC or other intelligent device serving as a conversion. the master in thermostatic, process-control, or
Idle Mode
monitoring applications. The µC is typically a power management or keyboard controller, generating SPI serial Pull CS low to enter idle mode. In idle mode, the ADC commands by “bit-banging” GPIO pins. is not converting. The serial interface is still active and temperature data from the last completed conversion can Two conversion rates are available; the MAX6627 still be read. continuously converts data every 0.5s, and the MAX6628 continuously converts data every 8s. Either device can
Power-On Reset
be read at any time and provide the data from the last The POR supply voltage of the MAX6627/MAX6628 is conversion. The slower version provides minimal power typically 1.6V. Below this supply voltage, the interface consumption under all operating conditions. Or, by is inactive and the data register is set to the POR state, 0.5s 8s SAMPLE SAMPLE 0.25s RATE RATE CONVERSION TIME MAX6627 ADC CONVERTING ADC IDLE MAX6628 Figure 1. Free-Running Conversion Time and Rate Relationships
Table 1. Data Output Format D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
MSB LSB Sign Low High-Z High-Z Data Data www.maximintegrated.com Maxim Integrated │ 6