MCP9844 ±1°C Accurate, 1.8V Digital Temperature Sensor Features: Description: 2 • 1MHz, 2-Wire I C™ Interface • User-Selectable Measurement Resolution: - +0.5°C, +0.25°C, +0.125°C, +0.0625°C • User-Programmable Temperature Limits: - Temperature Window Limit - Critical Temperature Limit • User-Programmable Temperature Alert Output • Specified VDD Range: 1.7V to 3.6V • Operating Current: 100 µA (typical) • Available Package: 8-Pin TDFN Microchip Technology Inc.’s MCP9844 digital temperature sensor converts temperature from -40°C to +125°C to a digital word. It provides an accuracy of ±0.2°C/±1°C (typical/maximum) from +75°C to +95°C with an operating voltage of 1.7V to 3.6V. Temperature Sensor Features: • Temperature-to-Digital Converter (°C) • Sensor Accuracy: - ±0.2°C/±1°C (typ./max.) +75°C to +95°C - ±0.5°C/±2°C (typ./max.) +40°C to +125°C - ±1°C/±3°C (typ./max.) -40°C to +125°C Typical Applications: • • • • • • • • • • The MCP9844 digital temperature sensor comes with user-programmable registers that provide flexibility for temperature sensing applications. The registers allow user-selectable settings such as Shutdown or LowPower modes, and the specification of temperature event boundaries. When the temperature changes beyond the specified event boundary limits, the MCP9844 outputs an Alert signal at the Event pin. The user has the option of setting the temperature event output signal polarity as either an active-low or activehigh comparator output for the thermostat operation, or as a temperature event interrupt output for microprocessor-based systems. This sensor has an industry standard I2C Fast Mode Plus compatible 1 MHz serial interface. Package Types Temperature Sensing for Solid State Drive (SSD) General Purpose Temperature Datalog General Purpose Industrial Applications Industrial Freezers and Refrigerators Food Processing Personal Computers and Servers PC Peripherals Consumer Electronics Handheld/Portable Devices 8-Pin 2x3 TDFN * A0 1 A1 2 A2 3 GND 4 8 VDD EP 9 7 Event 6 SCL 5 SDA * Includes Exposed Thermal Pad (EP); see Table 3-1. Temperature Accuracy (°C) 3.0 2.0 Spec. Limits VDD = 1.7 V to 3.6 V 16 units 1.0 0.0 +Std. Dev. Average -Std. Dev. -1.0 -2.0 -3.0 -40 -20 0 20 40 60 TA (°C) 2013 Microchip Technology Inc. 80 100 120 DS20005192B-page 1 MCP9844 1.0 †Notice: Stresses above those listed under “Maximum ratings” may cause permanent damage to the device. This is a stress rating only and functional operation of the device at those or any other conditions above those indicated in the operational listings of this specification is not implied. Exposure to maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS Absolute Maximum Ratings † VDD.................................................................................. 4.0V Voltage at all Input/Output pins ............... GND – 0.3V to 4.0V Pin A0....................................................... GND – 0.3V to 11V Storage temperature .....................................-65°C to +150°C Ambient temp. with power applied ................-40°C to +125°C Junction Temperature (TJ)........................................... +150°C ESD protection on all pins (HBM:MM) ................. (4 kV:200V) Latch-Up Current at each pin (25°C)........................ ±200 mA TEMPERATURE SENSOR DC CHARACTERISTICS Electrical Specifications: Unless otherwise indicated, VDD = 1.7V to 3.6V, GND = Ground, and TA = -40°C to +125°C. Parameters Sym. Min. Typ. Max. Unit TACY -1.0 ±0.2 +1.0 °C +40°C < TA +125°C -2.0 ±0.5 +2.0 °C -40°C < TA +125°C -3.0 ±1 +3.0 °C — 30 — ms Conditions Temperature Sensor Accuracy +75°C < TA +95°C VDD = 1.8V Temperature Conversion Time 0.5°C/bit tCONV 0.25°C/bit (POR default) — 65 125 ms 0.125°C/bit — 130 — ms 0.0625°C/bit — 260 — ms 15 s/sec (typical) (See Section 5.2.4) Power Supply Specified Voltage Range VDD 1.7 — 3.6 V Operating Current IDD — 100 500 µA Shutdown Current ISHDN — 0.2 1 µA TA = 85°C Power On Reset (POR) VPOR — 1.4 1.6 V Threshold for falling VDD voltage Settling time after POR tPOR — — 1 ms For warm and cold power cycles Line Regulation °C — 0.2 — °C VDD = 1.7V to 3.6V Event Output (Open-Drain output, external pull-up resistor required), see Section 5.2.3 High-level Current (leakage) IOH — — 1 µA VOH = VDD Low-level Voltage VOL — — 0.4 V IOL= 3 mA (Active-Low, Pull-up Resistor) — s Time to 63% (89°C) Thermal Response, from +25°C (Air) to +125°C (oil bath) TDFN-8 DS20005192B-page 2 tRES — 0.7 2013 Microchip Technology Inc. MCP9844 INPUT/OUTPUT PIN DC CHARACTERISTICS Electrical Specifications: Unless otherwise indicated, VDD = 1.7V to 3.6V, GND = Ground and TA = -40°C to +125°C. Parameters Sym. Min. Typ. Max. Units V Conditions Serial Input/Output (SCL, SDA, A0, A1, A2) Input High-level Voltage VIH 0.7VDD — — Low-level Voltage VIL — — 0.3VDD V Input Current IIN — — ±5 µA Input Impedance (A0, A1, A2) ZIN — 1 — M VIN > VIH Input Impedance (A0, A1, A2) ZIN — 200 — k VIN < VIL Low-level Voltage VOL — — 0.4 V IOL= 3 mA High-level Current (leakage) IOH — — 1 µA VOH = VDD Low-level Current IOL 20 — — mA VOL = 0.4V, VDD ≥ 2.2V 6 — — mA VOL = 0.6V Capacitance CIN — 5 — pF VHYST — 0.05VDD — V TSP — — 50 ns SDA and SCL only Output (SDA only) SDA and SCL Inputs Hysteresis Spike Suppression TEMPERATURE CHARACTERISTICS Electrical Specifications: Unless otherwise indicated, VDD = 1.7V to 3.6V, GND = Ground, and TA = -40°C to +125°C. Parameters Sym. Min. Typ. Max. Units Specified Temperature Range TA -40 — +125 °C Operating Temperature Range TA -40 — +125 °C Storage Temperature Range TA -65 — +150 °C JA — 52.5 — °C/W Conditions Temperature Ranges Note 1 Thermal Package Resistances Thermal Resistance, 8L-TDFN Note 1: Operation in this range must not cause TJ to exceed Maximum Junction Temperature (+150°C). 2013 Microchip Technology Inc. DS20005192B-page 3 MCP9844 SERIAL INTERFACE TIMING SPECIFICATIONS Electrical Specifications: Unless otherwise indicated, GND = Ground, TA = -40°C to +125°C, and CL = 80 pF Note 1. VDD= 1.7V to 3.6V 100 kHz Parameters VDD= 2.2V to 3.6V 400 kHz 1000 kHz Sym. Min. Max. Min. Max. Min. Max. Units fSCL 10 100 10 400 10 1000 kHz Low Clock (Note 2) tLOW 4700 — 1300 — 500 — ns High Clock tHIGH 4000 — 600 — 260 — ns 2-Wire I2 C™ Interface Serial port frequency (Note 2, 4) Rise time (Note 5) tR — 1000 20 300 — 120 ns Fall time (Note 5) tF 20 300 20 300 — 120 ns Data in Setup time (Note 3) tSU:DAT 250 — 100 — 50 — ns Data in Hold time (Note 6) tHD:DI 0 — 0 — 0 — ns Data out Hold time (Note 4) tHD:DO 200 900 200 900 0 350 ns Start Condition Setup time tSU:STA 4700 — 600 — 260 — ns Start Condition Hold time tHD:STA 4000 — 600 — 260 — ns Stop Condition Setup time tSU:STO 4000 — 600 — 260 — ns Bus Idle/Free tB-FREE 4700 — 1300 — 500 — ns tOUT 25 35 25 35 25 35 ms Cb — — — 400 — 100 pf Time out Bus Capacitive load Note 1: 2: 3: 4: 5: 6: All values referred to VIL MAX and VIH MIN levels. If tLOW > tOUT, the temperature sensor I2C interface will time out. A Repeat Start command is required for communication. This device can be used in a Standard mode I2C bus system, but the requirement tSU:DAT 250 ns must be met. This device does not stretch SCL Low period. It outputs the next data bit to the SDA line within tR 2 MAX + tSU:DAT MIN = 1000 ns + 250 ns = 1250 ns (according to the Standard mode I C bus specification) before the SCL line is released. As a transmitter, the device provides internal minimum delay time tHD:DAT MIN to bridge the undefined region (min. 200 ns) of the falling edge of SCL tF MAX to avoid unintended generation of Start or Stop conditions. Characterized but not production tested. As a receiver, SDA should not be sampled at the falling edge of SCL. SDA can transition tHD:DI 0 ns after SCL toggles Low. RE E :F :S TO tB U tS W O tH D: D I tS /t U H :D I D :D O tO UT tR ,t F SD A SC L tL tH tS IG H U: ST tS O U :D I TIMING DIAGRAM Start Condition DS20005192B-page 4 Data Transmission Stop Condition 2013 Microchip Technology Inc. MCP9844 2.0 TYPICAL PERFORMANCE CURVES The graphs and tables provided following this note are a statistical summary based on a limited number of samples and are provided for informational purposes only. The performance characteristics listed herein are not tested or guaranteed. In some graphs or tables, the data presented may be outside the specified operating range (e.g., outside specified power supply range) and therefore outside the warranted range. Note: Note: Unless otherwise indicated, VDD = 1.7V to 3.6V, GND = Ground, SDA/SCL pulled-up to VDD, and TA = -40°C to +125°C. 2.0 150 Spec. Limits VDD = 1.7 V to 3.6 V 16 units 125 1.0 IDD (µA) Temperature Accuracy (°C) 3.0 0.0 +Std. Dev. Average -Std. Dev. -1.0 -2.0 75 50 -3.0 -40 -20 0 FIGURE 2-1: 20 40 60 TA (°C) 80 100 120 -40 0 20 25% Supply Current Vs. 0.50 1.00 0.75 0.50 0.25 0.00 -0.25 -0.50 -0.75 -1.00 0.00 -40 -20 0 20 Temperature Accuracy (°C) FIGURE 2-2: Temperature Accuracy Histogram, TA = + 85 °C. FIGURE 2-5: Temperature. 40 60 TA (°C ) 80 100 120 Shutdown Current Vs. 1.8 TA = +25 °C VDD = 1.7 V - 3.6 V 16 units 1.6 VPOR (V) Occurrences 100 120 0 25 0.25 0% 75% 80 0.75 50% 100% 40 60 TA (°C) 1.00 TA = +85 °C VDD = 1.7 V - 3.6 V 16 units ISHDN (µA) Occurrences -20 FIGURE 2-4: Temperature. Temperature Accuracy. 100% 75% 100 50% 25% Rising VDD 1.4 1.2 Falling VDD 1 0.8 Temperature Accuracy (°C) FIGURE 2-3: Temperature Accuracy Histogram, TA = + 25 °C. 2013 Microchip Technology Inc. 1.00 0.75 0.50 0.25 0.00 -0.25 -0.50 -0.75 -1.00 0% 0.6 -40 -20 0 20 40 60 TA (°C) 80 100 120 FIGURE 2-6: Power-On Reset Threshold Voltage Vs. Temperature. DS20005192B-page 5 MCP9844 Note: Unless otherwise indicated, VDD = 1.7V to 3.6V, GND = Ground, SDA/SCL pulled-up to VDD, and TA = -40°C to +125°C. Normallized Temp. Error (°C) Eve ent & SDA VOL (V) 0.4 SDA, IOL = 20 mA VDD = 2.2 V to 3.6 V 0.3 0.2 0.1 01 Event, IOL = 3 mA 0 -40 -20 0 FIGURE 2-7: Vs. Temperature. 20 40 60 TA (°C) 80 3.0 2.0 1.0 0.0 -1.0 -2.0 -3.0 100 120 Event Output and SDA VOL VDD = 1.7 V VDD = 3.6 V -40 -20 0 20 40 60 TA (°C) 80 100 120 FIGURE 2-10: Line Regulation: Change in Temperature Accuracy Vs. Change in VDD. 200 35 175 tCONV (ms) I2C Bus tOUT (ms) 0.0625 °C/LSb 150 125 100 75 0.125 °C/LSb 50 0.25 °C/LSb 25 30 0.5 °C/LSb 0 25 -40 -20 0 20 40 60 TA (°C) 80 100 120 FIGURE 2-8: Temperature Conversion Rate Vs. Temperature. -40 -20 FIGURE 2-11: Temperature. 0 20 40 60 TA (°C) 80 100 120 I2C™ Protocol Time-out Vs. 50 SDA IOL (mA) VOL = 0.6V 40 30 20 10 -40 -20 0 FIGURE 2-9: DS20005192B-page 6 20 40 60 TA (°C) 80 100 120 SDA IOL Vs. Temperature. 2013 Microchip Technology Inc. MCP9844 3.0 PIN DESCRIPTION The descriptions of the pins are listed in Table 3-1. TABLE 3-1: PIN FUNCTION TABLES MCP9844 Symbol Description TDFN 1 A0 Slave Address 2 A1 Slave Address 3 A2 4 GND 5 SDA Serial Data Line 6 SCL Serial Clock Line 7 Event 8 VDD Power Pin 9 EP Exposed Thermal Pad (EP); can be connected to GND. 3.1 Slave Address Ground Temperature Alert Output Address Pins (A0, A1, A2) 3.4 These pins are device address input pins. Serial Clock Line (SCL) The address pins correspond to the Least Significant bits (LSb) of the address bits. The Most Significant bits (MSb) are A6, A5, A4, A3. Refer to Table 3-2. The SCL is a clock input pin. All communication and timing is relative to the signal on this pin. The clock is generated by the host or master controller on the bus. (See Section 4.0 “Serial Communication”.) TABLE 3-2: 3.5 Device Sensor Note 1: MCP9844 ADDRESS BYTE Address Code Slave Address A6 A5 A4 A3 A2 A1 A0 0 0 1 1 X1 X1 X1 User-selectable address is shown by X, where X is ‘1’ or ‘0’ for VDD and GND, respectively The MCP9844 temperature Event output pin is an open-drain output. The device outputs a signal when the ambient temperature goes beyond the user programmed temperature limit. (See Section 5.2.3 “Event Output Configuration”.) 3.6 All address pins have an internal pull-down resistor. 3.2 Ground Pin (GND) Temperature Alert, Open-Drain Output (Event) Power Pin (VDD) VDD is the power pin. The operating voltage range, as specified in the DC electrical specification table, is applied on this pin. The GND pin is the system ground pin. 3.7 3.3 Serial Data Line (SDA) The SDA is a bidirectional input/output pin used to serially transmit data to/from the host controller. This pin requires a pull-up resistor. (See Section 4.0 “Serial Communication”.) 2013 Microchip Technology Inc. Exposed Thermal Pad (EP) There is an internal electrical connection between the Exposed Thermal Pad (EP) and the GND pin; they can be connected to the same potential on the Printed Circuit Board (PCB). This provides better thermal conduction from the PCB to the die. DS20005192B-page 7 MCP9844 4.0 SERIAL COMMUNICATION 4.1 2-Wire Standard Mode I2C™ Protocol-Compatible Interface The MCP9844 serial clock input (SCL) and the bidirectional serial data line (SDA) form a 2-wire bidirectional Standard mode I2C compatible communication port (refer to the Input/Output Pin DC Characteristics table and the Serial Interface Timing Specifications table). The following MCP9844 bus protocol is defined in Table 4-1. TABLE 4-1: MCP9844 SERIAL BUS PROTOCOL DESCRIPTIONS Term Description Master The device that controls the serial bus, typically a microcontroller. Slave The device addressed by the master, such as the MCP9844. Transmitter Device sending data to the bus. Receiver Device receiving data from the bus. START A unique signal from the master to initiate serial interface with a slave. STOP A unique signal from the master to terminate serial interface from a slave. Read/Write A read or write to the MCP9844 registers. ACK A receiver Acknowledges (ACK) the reception of each byte by polling the bus. NAK A receiver Not-Acknowledges (NAK) or releases the bus to show End-of-Data (EOD). Busy Communication is not possible because the bus is in use. Not Busy The bus is in the Idle state, both SDA and SCL remain high. Data Valid SDA must remain stable before SCL becomes high in order for a data bit to be considered valid. During normal data transfers, SDA only changes state while SCL is low. 4.1.1 DATA TRANSFER Data transfers are initiated by a Start condition (START), followed by a 7-bit device address and a read/write bit. An Acknowledge (ACK) from the slave confirms the reception of each byte. Each access must be terminated by a Stop condition (STOP). Repeated communication is initiated after tB-FREE. DS20005192B-page 8 This device does not support sequential register read/ write. Each register needs to be addressed using the Register Pointer. This device supports the Receive Protocol. The register can be specified using the pointer for the initial read. Each repeated read or receive begins with a Start condition and address byte. The MCP9844 retains the previously selected register. Therefore, they output data from the previously specified register (repeated pointer specification is not necessary). 4.1.2 MASTER/SLAVE The bus is controlled by a master device (typically a microcontroller) that controls the bus access and generates the Start and Stop conditions. The MCP9844 is a slave device and does not control other devices in the bus. Both master and slave devices can operate as either transmitter or receiver. However, the master device determines which mode is activated. 4.1.3 START/STOP CONDITION A high-to-low transition of the SDA line (while SCL is high) is the Start condition. All data transfers must be preceded by a Start condition from the master. A lowto-high transition of the SDA line (while SCL is high) signifies a Stop condition. If a Start or Stop condition is introduced during data transmission, the MCP9844 releases the bus. All data transfers are ended by a Stop condition from the master. 4.1.4 ADDRESS BYTE Following the Start condition, the host must transmit an 8-bit address byte to the MCP9844. The address for the MCP9844 temperature sensor is ‘0011,A2,A1,A0’ in binary, where the A2, A1 and A0 bits are set externally by connecting the corresponding pins to VDD ‘1’ or GND ‘0’. The 7-bit address transmitted in the serial bit stream must match the selected address for the MCP9844 to respond with an ACK. Bit 8 in the address byte is a read/write bit. Setting this bit to ‘1’ commands a read operation, while ‘0’ commands a write operation (see Figure 4-1). Address Byte 1 SCL 2 3 4 5 6 7 8 0 0 1 1 A2 A1 A0 SDA 9 A C K Start Address Code Slave Address R/W MCP9844 Response FIGURE 4-1: Device Addressing. 2013 Microchip Technology Inc. MCP9844 4.1.5 DATA VALID After the Start condition, each bit of data in the transmission needs to be settled for a time specified by tSU-DATA before SCL toggles from low-to-high (see Serial Interface Timing Specifications table). 4.1.6 4.1.7 TIME OUT (TOUT) If the SCL stays low or high for time specified by tOUT, the MCP9844 resets the serial interface. This dictates the minimum clock speed as specified in the specification. ACKNOWLEDGE (ACK/NAK) Each receiving device, when addressed, is obliged to generate an ACK bit after the reception of each byte. The master device must generate an extra clock pulse for ACK to be recognized. The acknowledging device pulls down the SDA line for tSU-DATA before the low-to-high transition of SCL from the master. SDA also needs to remain pulled down for tH-DATA after a high-to-low transition of SCL. During read, the master must signal an End-of-Data (EOD) to the slave by not generating an ACK bit (NAK) once the last bit has been clocked out of the slave. In this case, the slave will leave the data line released to enable the master to generate the Stop condition. 2013 Microchip Technology Inc. DS20005192B-page 9 MCP9844 5.0 registers and a 2-wire I2C protocol compatible serial interface. Figure 5-1 shows a block diagram of the register structure. FUNCTIONAL DESCRIPTION The MCP9844 temperature sensors consist of a band gap type temperature sensor, a Delta-Sigma Analog-toDigital Converter ( ADC), user-programmable MCP9844 Temperature Sensor Hysteresis Shutdown Critical Trip Lock Alarm Win. Lock Bit Clear Event Event Status Output Control Critical Event only Band Gap Temperature Sensor Event Polarity Event Comp./Int. Configuration Temperature ADC TUPPER TLOWER 0.5°C/bit 0.25°C/bit 0.125°C/bit 0.0625°C/bit TCRIT Manufacturer ID Device ID/Rev. Resolution Capability Shutdown Status I2C™ Bus Time-out Selected Resolution Temp. Range Accuracy Output Feature Register Pointer Standard I2C Interface A0 A1 FIGURE 5-1: DS20005192B-page 10 A2 Event SDA SCL VDD GND Functional Block Diagram. 2013 Microchip Technology Inc. MCP9844 5.1 Registers The MCP9844 device has several registers that are user accessible. These registers include the Capability register, Configuration register, Event Temperature Upper-Boundary and Lower-Boundary Trip registers, Critical Temperature Trip register, Temperature register, Manufacturer Identification register and Device Identification register. The Temperature register is read-only and is used to access the ambient temperature data. The data is loaded in parallel to this register after tCONV. The Event Temperature Upper-Boundary and Lower-Boundary Trip registers are read/writes. If the ambient temperature drifts beyond the user-specified limits, the MCP9844 device outputs a signal using the Event pin (refer to Section 5.2.3 “Event Output Configuration”). In addition, the Critical Temperature Trip register is used to provide an additional critical temperature limit. REGISTER 5-1: The Capability register is used to provide bits describing the MCP9844’s capability in measurement resolution, measurement range and device accuracy. The device Configuration register provides access to configure the MCP9844’s various features. These registers are described in further detail in the following sections. The registers are accessed by sending a Register Pointer to the MCP9844 using the serial interface. This is an 8-bit write-only pointer. Register 5-1 describes the pointer or the address of each register. This device will not acknowledge commands to register pointers other than those listed in Register 5-1. REGISTER POINTER (WRITE ONLY) W-0 W-0 W-0 W-0 — — — — W-0 W-0 W-0 W-0 Pointer Bits bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ -n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown bit 7-4 Writable Bits: Write ‘0’ bit 3-0 Pointer Bits: 0000 = Capability register 0001 = Configuration register (CONFIG) 0010 = Event Temperature Upper-Boundary Trip register (TUPPER) 0011 = Event Temperature Lower-Boundary Trip register (TLOWER) 0100 = Critical Temperature Trip register (TCRIT) 0101 = Temperature register (TA) 0110 = Manufacturer ID register 0111 = Device ID/Revision register 1000 = Reserved 1001 = Resolution register 1XXX = Unused (The device will not acknowledge commands to other pointer locations.) 2013 Microchip Technology Inc. DS20005192B-page 11 MCP9844 TABLE 5-1: Register Pointer (Hex) 0x00 0x01 0x02 0x03 0x04 0x05 0x06 0x07 0x08 0x09 BIT ASSIGNMENT SUMMARY FOR ALL TEMPERATURE SENSOR REGISTERS (SEE SECTION 5.3) Bit Assignment MSB/ LSB 7 6 5 MSB LSB MSB LSB 0 SHDN Status 0 Crt. Loc. 0 tOUT Range 0 Win. Loc. 0 1 0 Int. Clr. MSB LSB 0 23 °C 0 0 2 1 2 °C 2 °C 4 3 2 1 0 0 0 0 0 0 Resolution Range Accuracy Event 0 0 Hysteresis SHDN Evt. Stat. Evt. Cnt. Evt. Sel. Evt. Pol. Evt. Mod. SIGN 0 2 °C 27°C -1 2 °C 7 26°C 25°C 24°C -2 0 0 6 5 4 2 °C MSB 0 0 0 SIGN 2 °C 2 °C 2 °C LSB 23°C 22°C 21°C 20°C 2-1°C 2-2°C 0 0 5 4 MSB 0 0 0 SIGN 27 °C 2 °C 2 °C LSB 23°C 22°C 21°C 20°C 2-1°C 2-2°C 0 0 MSB TA TCRIT TA TUPPER TA TLOWER SIGN 27°C 26°C 25°C 24°C LSB 23°C 0 0 0 0 0 0 0 0 22°C 0 1 0 0 0 0 0 0 21°C 0 0 0 0 0 0 0 0 20°C 0 1 0 0 0 0 0 0 2-1°C 0 0 0 0 0 0 0 0 2-2°C 0 1 1 0 1 0 0 0 2-3°C 2-4°C 0 0 0 0 1 0 0 1 1 0 0 1 0 0 Resolution MSB LSB MSB LSB MSB LSB MSB LSB DS20005192B-page 12 6 2 °C 2 °C 2013 Microchip Technology Inc. MCP9844 5.1.1 CAPABILITY REGISTER This is a read-only register used to identify the temperature sensor capability. For example, the MCP9844 device is capable of providing temperature at 0.25°C resolution, measuring temperature below and above 0°C, providing ±1°C and ±2°C accuracy over the active and monitor temperature ranges (respectively) and providing user-programmable temperature event boundary trip limits. Register 5-2 describes the Capability register. These functions are described in further detail in the following sections. REGISTER 5-2: CAPABILITY REGISTER (READ-ONLY) ADDRESS ‘0000 0000’b U-0 U-0 U-0 U-0 U-0 U-0 U-0 U-0 — — — — — — — — bit 15 bit 8 R-1 R-1 R-1 SHDN Status tOUT Range — R-0 R-1 Resolution R-1 R-1 R-1 Meas. Range Accuracy Temp. Alarm bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ -n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown bit 15-8 Unimplemented: Read as ‘0’ bit 7 Event Output Status During Shutdown (SHDN Status): 0 = Event output remains in previous state. If the output asserts before shutdown command, it remains asserted during shutdown. 1 = Event output deasserts during shutdown. After shutdown, it takes tCONV to reassert the event output (power-up default) bit 6 I2C™ Bus Time-Out (tOUT Range): 0 = Bus time-out range is 10 ms to 60 ms 1 = Bus time-out range is 25 ms to 35 ms (power-up default) bit 5 Unimplemented: Read as ‘1’ bit 4-3 Resolution: 00 = 0.5°C 01 = 0.25°C (power-up default) 10 = 0.125°C 11 = 0.0625°C These bits reflect the selected resolution (see Section 5.2.4 “Temperature Resolution”) bit 2 Temperature Measurement Range (Meas. Range): 0 = TA 0 (decimal) for temperature below 0°C 1 = The part can measure temperature below 0°C (power-up default) 2013 Microchip Technology Inc. DS20005192B-page 13 MCP9844 CAPABILITY REGISTER (READ-ONLY) ADDRESS ‘0000 0000’b (CONTINUED) REGISTER 5-2: bit 1 Accuracy: 0 = Accuracy ±2°C from +75°C to +95°C (Active Range) and ±3°C from +40°C to +125°C (Monitor Range) 1 = Accuracy ±1°C from +75°C to +95°C (Active Range) and ±2°C from +40°C to +125°C (Monitor Range) bit 0 Temperature Alarm: 0 = No defined function (This bit will never be cleared or set to ‘0’) 1 = The part has temperature boundary trip limits (TUPPER/TLOWER/TCRIT registers) and a temperature event output (JC 42.4 required feature) 1 2 3 4 5 6 7 8 1 A 2 A 1 A 0 W C K 2 3 4 5 6 7 8 SCL SDA S 0 0 1 1 A 0 0 0 0 0 0 0 0 Address Byte Capability Pointer MCP9844 MCP9844 1 2 3 4 5 A C K 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 SCL SDA S A A N 0 0 1 1 A A A R C 0 0 0 0 0 0 0 0 C 0 0 0 0 1 1 1 1 A P 2 1 0 K Address Byte MCP9844 K MSB Data K LSB Data Master Master FIGURE 5-2: Timing Diagram for Reading the Capability Register (See Section 4.0 “Serial Communication”). DS20005192B-page 14 2013 Microchip Technology Inc. MCP9844 5.1.2 SENSOR CONFIGURATION REGISTER (CONFIG) The MCP9844 device has a 16-bit Configuration register (CONFIG) that allows the user to set various functions for a robust temperature monitoring system. Bits 10 through 0 are used to select the event output boundary hysteresis, device Shutdown or Low-Power mode, temperature boundary and critical temperature lock, and temperature event output enable/disable. In addition, the user can select the event output condition (output set for TUPPER and TLOWER temperature boundary or TCRIT only), read event output status and set event output polarity and mode (Comparator Output or Interrupt Output mode). Conversion or Shutdown mode is selected using bit 8. In Shutdown mode, the band gap temperature sensor circuit stops converting temperature and the Ambient Temperature register (TA) holds the previous successfully converted temperature data (see Section 5.2.1 “Shutdown Mode”). Bits 7 and 6 are used to lock the user-specified boundaries TUPPER, TLOWER and TCRIT to prevent an accidental rewrite. Bits 5 through 0 are used to configure the temperature Event output pin. All functions are described in Register 5-3 (see Section 5.2.3 “Event Output Configuration”). The temperature hysteresis bits 10 and 9 can be used to prevent output chatter when the ambient temperature gradually changes beyond the user specified temperature boundary (see Section 5.2.2 “Temperature Hysteresis (THYST)”). The Continuous CONFIGURATION REGISTER (CONFIG) ADDRESS ‘0000 0001’b REGISTER 5-3: U-0 U-0 U-0 U-0 U-0 — — — — — R/W-0 R/W-0 THYST R/W-0 SHDN bit 15 bit 8 R/W-0 R/W-0 R/W-0 R-0 R/W-0 R/W-0 R/W-0 R/W-0 Crit. Lock Win. Lock Int. Clear Event Stat. Event Cnt. Event Sel. Event Pol. Event Mod. bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ -n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared bit 15-11 Unimplemented: Read as ‘0’ bit 10-9 TUPPER and TLOWER Limit Hysteresis (THYST): 00 = 0°C (power-up default) 01 = 1.5°C 10 = 3.0°C 11 = 6.0°C x = Bit is unknown (Refer to Section 5.2.3 “Event Output Configuration”) This bit can not be altered when either of the lock bits are set (bit 6 and bit 7). This bit can be programmed in Shutdown mode. bit 8 Shutdown Mode (SHDN): 0 = Continuous Conversion (power-up default) 1 = Shutdown (Low-Power mode) In shutdown, all power-consuming activities are disabled, though all registers can be written to or read. Event output will deassert. This bit cannot be set ‘1’ when either of the lock bits is set (bit 6 and bit 7). However, it can be cleared ‘0’ for Continuous Conversion while locked (Refer to Section 5.2.1 “Shutdown Mode”). 2013 Microchip Technology Inc. DS20005192B-page 15 MCP9844 REGISTER 5-3: bit 7 CONFIGURATION REGISTER (CONFIG) ADDRESS ‘0000 0001’b TCRIT Lock Bit (Crit. Lock): 0 = Unlocked. TCRIT register can be written. (power-up default) 1 = Locked. TCRIT register can not be written When enabled, this bit remains set ‘1’ or locked until cleared by internal reset (Section 5.3 “Summary of Power-on Default”). This bit does not require a double-write. This bit can be programmed in Shutdown mode. bit 6 TUPPER and TLOWER Window Lock Bit (Win. Lock): 0 = Unlocked. TUPPER and TLOWER registers can be written. (power-up default) 1 = Locked. TUPPER and TLOWER registers can not be written When enabled, this bit remains set ‘1’ or locked until cleared by power-on Respell (Section 5.3 “Summary of Power-on Default”). This bit does not require a double-write. This bit can be programmed in Shutdown mode. bit 5 Interrupt Clear (Int. Clear) Bit: 0 = No effect (power-up default) 1 = Clear interrupt output. When read this bit returns ‘0’ This bit clears the Interrupt flag which deasserts event output. In Shutdown mode, the event output is always deasserted. Therefore, setting this bit in Shutdown mode clears the interrupt after the device returns to normal operation. bit 4 Event Output Status (Event Stat.) Bit: 0 = Event output is not asserted by the device (power-up default) 1 = Event output is asserted as a comparator/Interrupt or critical temperature output In Shutdown mode this bit will clear because event output is always deasserted in Shutdown mode. bit 3 Event Output Control (Event Cnt.) Bit: 0 = Event output Disabled (power-up default) 1 = Event output Enabled This bit can not be altered when either of the lock bits is set (bit 6 and bit 7). This bit can be programmed in Shutdown mode, but event output will remain deasserted. bit 2 Event Output Select (Event Sel.) Bit: 0 = Event output for TUPPER, TLOWER and TCRIT (power-up default) 1 = TA ≥ TCRIT only. (TUPPER and TLOWER temperature boundaries are disabled.) When the Alarm Window Lock bit is set, this bit cannot be altered until unlocked (bit 6). This bit can be programmed in Shutdown mode, but event output will remain deasserted. bit 1 Event Output Polarity (Event Pol.) Bit: 0 = Active-low (power-up default. Pull-up resistor required) 1 = Active-high This bit cannot be altered when either of the lock bits is set (bit 6 and bit 7). This bit can be programmed in Shutdown mode, but event output will remain deasserted, see Section 5.2.3 “Event Output Configuration” bit 0 Event Output Mode (Event Mod.) Bit: 0 = Comparator output (power-up default) 1 = Interrupt output This bit cannot be altered when either of the lock bits is set (bit 6 and bit 7). This bit can be programmed in Shutdown mode, but event output will remain deasserted. DS20005192B-page 16 2013 Microchip Technology Inc. MCP9844 Writing to the CONFIG Register to Enable the Event Output pin <0000 0000 0000 1000>b. 1 2 3 4 5 6 7 8 1 A 2 A 1 A 0 W C 2 3 4 5 6 7 8 SCL SDA S 0 0 1 1 A K Address Byte 0 0 0 0 0 0 0 1 Configuration Pointer MCP9844 MCP9844 1 A C K 2 3 4 5 6 7 8 0 0 0 0 0 0 0 0 1 A C K 2 3 4 5 6 7 8 0 0 0 0 1 0 0 0 MSB Data A C K P LSB Data MCP9844 MCP9844 Note: this is an example routine: i2c_start(); // send START command i2c_write(AddressByte & 0xFE); //WRITE Command i2c_write(0x01); // Write CONFIG Register i2c_write(0x00); // Write data i2c_write(0x08); // Write data i2c_stop(); // send STOP command //also, make sure bit 0 is cleared ‘0’ FIGURE 5-3: Timing Diagram for Writing to the Configuration Register (See Section 4.0 “Serial Communication”. 2013 Microchip Technology Inc. DS20005192B-page 17 MCP9844 • Reading the CONFIG Register. 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 SCL SDA It is not necessary to select the Register Pointer if it was set from the previous read/ write. Note: S 0 0 1 1 A 2 A 1 A A 0 W C K Address Byte Configuration Pointer MCP9844 MCP9844 1 2 3 4 A C K 0 0 0 0 0 0 0 1 5 6 7 8 1 A 2 A 1 A 0 R C 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 SCL SDA S 0 0 1 1 A K 0 0 0 0 0 0 0 0 Address Byte A C K 0 0 0 0 1 0 0 0 P LSB Data MSB Data MCP9844 N A K Master Master Note: this is an example routine: i2c_start(); // send START command i2c_write(AddressByte & 0xFE); //WRITE Command //also, make sure bit 0 is cleared ‘0’ i2c_write(0x01); // Write CONFIG Register i2c_start(); // send Repeat START command i2c_write(AddressByte | 0x01); //READ Command //also, make sure bit 0 is set ‘1’ UpperByte = i2c_read(ACK); // READ 8 bits //and Send ACK bit LowerByte = i2c_read(NAK); // READ 8 bits //and Send NAK bit i2c_stop(); // send STOP command FIGURE 5-4: Timing Diagram for Reading from the Configuration Register (See Section 4.0 “Serial Communication”). DS20005192B-page 18 2013 Microchip Technology Inc. MCP9844 5.1.3 UPPER/LOWER/CRITICAL TEMPERATURE LIMIT REGISTERS (TUPPER/TLOWER/TCRIT) The MCP9844 device has a 16-bit read/write Event Output Temperature Upper-Boundary Trip register (TUPPER), a 16-bit Lower-Boundary Trip register (TLOWER) and a 16-bit Critical Boundary Trip register (TCRIT) that contains 11-bit data in two’s complement format (0.25°C). This data represents the maximum and minimum temperature boundary or temperature window that can be used to monitor ambient temperature. If this feature is enabled (Section 5.1.2 “Sensor Configuration Register (CONFIG)”) and the ambient temperature exceeds the specified boundary or window, the MCP9844 asserts an event output. (Refer to Section 5.2.3 “Event Output Configuration”). REGISTER 5-4: UPPER/LOWER/CRITICAL TEMPERATURE LIMIT REGISTER (TUPPER/TLOWER/ TCRIT) ADDRESS ‘0000 0010’b/‘0000 0011’b/‘0000 0100’b (Note 1) U-0 U-0 U-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 — — — Sign 27°C 26°C 25°C 24°C bit 15 bit 8 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 U-0 U-0 23°C 22°C 21°C 20°C 2-1°C 2-2°C — — bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ -n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared bit 15-13 Unimplemented: Read as ‘0’ bit 12 Sign: 0 = TA 0°C 1 = TA 0°C bit 11-2 TUPPER/TLOWER/TCRIT: Temperature boundary trip data in two’s complement format. bit 1-0 Unimplemented: Read as ‘0’ x = Bit is unknown Note 1: This table shows two 16-bit registers for TUPPER, TLOWER and TCRIT located at ‘0000 0010b’, ‘0000 0011b’ and ‘0000 0100b’, respectively. 2013 Microchip Technology Inc. DS20005192B-page 19 MCP9844 Writing 90°C to the TUPPER Register <0000 0101 1010 0000>b. 1 2 3 4 5 6 7 8 0 0 1 1 A 2 A 1 A 0 W C 1 2 3 4 5 6 7 8 0 0 0 0 0 0 1 0 SCL SDA S A K Address Byte A C K TUPPER Pointer MCP9844 MCP9844 1 2 3 4 5 6 7 8 0 0 0 0 0 1 0 1 A C K 1 2 3 4 5 6 7 8 1 0 1 0 0 0 0 0 MSB Data A C K P LSB Data MCP9844 MCP9844 • Reading from the TUPPER Register. 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 SCL It is not necessary to select the Register Pointer if it was set from the previous read/write. Note: SDA S 0 0 1 1 A 2 A 1 A 0 A W C K 0 Address Byte 0 0 0 0 0 1 0 A C K TUPPER Pointer MCP9844 MCP9844 1 2 3 4 5 6 7 8 0 0 1 1 A 2 A 1 A 0 R C 1 2 3 4 5 6 7 8 0 0 0 0 0 1 0 1 1 2 3 4 5 6 7 8 1 0 1 0 0 0 0 0 SCL SDA S A K Address Byte A C K P LSB Data MSB Data MCP9844 N A K Master Master FIGURE 5-5: Timing Diagram for Writing and Reading from the TUPPER Register (See Section 4.0 “Serial Communication”). DS20005192B-page 20 2013 Microchip Technology Inc. MCP9844 5.1.4 AMBIENT TEMPERATURE REGISTER (TA) The MCP9844 device uses a band gap temperature sensor circuit to output analog voltage proportional to absolute temperature. An internal ADC is used to convert the analog voltage to a digital word. The converter resolution is set to 0.25°C + sign (11-bit data). The digital word is loaded to a 16-bit read-only Ambient Temperature register (TA) that contains 11-bit temperature data in two’s complement format. In addition, the TA register uses three bits (bits 15, 14 and 13) to reflect the Event pin state. This allows the user to identify the cause of the event output trigger (see Section 5.2.3 “Event Output Configuration”); bit 15 is set to ‘1’ if TA is greater than or equal to TCRIT, bit 14 is set to ‘1’ if TA is greater than TUPPER and bit 13 is set to ‘1’ if TA is less than TLOWER. The TA register bit assignment and boundary conditions are described in Register 5-5. The TA register bits (bits 12 through 0) are double-buffered. Therefore, the user can access the register while, in the background, the MCP9844 performs an Analogto-Digital conversion. The temperature data from the ADC is loaded in parallel to the TA register at tCONV refresh rate. REGISTER 5-5: R-0 AMBIENT TEMPERATURE REGISTER (TA) ADDRESS ‘0000 0101’b (Note 1) R-0 R-0 TA vs. TCRIT TA vs. TUPPER TA vs. TLOWER R-0 R-0 R-0 R-0 R-0 SIGN 27 °C 26 °C 25 °C 24 °C bit 15 bit 8 R-0 2 3 °C R-0 R-0 R-0 R-0 R-0 R-0 R-0 22 °C 21 °C 20 °C 2-1 °C 2-2 °C 2-3 °C 2-4 °C bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ -n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared bit 15 TA vs. TCRIT (1) Bit: 0 = TA TCRIT 1 = TA TCRIT bit 14 TA vs. TUPPER (1) Bit: 0 = TA TUPPER 1 = TA TUPPER bit 13 TA vs. TLOWER (1) Bit: 0 = TA TLOWER 1 = TA TLOWER bit 12 SIGN Bit: 0 = TA 0°C 1 = TA 0°C bit 11-0 Ambient Temperature (TA) Bits: (Note 2) 12-bit Ambient Temperature data in two’s complement format. x = Bit is unknown Note 1: Bits 15, 14 and 13 are not affected by the status of the event output configuration (bits 5 to 0 of CONFIG) (Register 5-3). 2: Bits 2, 1, and 0 may remain clear ‘0’ depending on the status of the resolution register. The power-up default is 0.25°C/bit, bits 1 and 0 remain clear ‘0’. 2013 Microchip Technology Inc. DS20005192B-page 21 MCP9844 5.1.4.1 TA bits to Temperature Conversion EQUATION 5-1: To convert the TA bits to decimal temperature, the upper three boundary bits 15, 14 and 13) must be masked out. Then determine the sign bit (bit 12) to check positive or negative temperature, shift the bits accordingly and combine the upper and lower bytes of the 16-bit register. The upper byte contains data for temperatures greater than 32°C while the lower byte contains data for temperature less than 32°C, including fractional data. When combining the upper and lower bytes, the upper byte must be right-shifted by 4 bits (or multiply by 24), and the lower byte must be left-shifted by 4 bits (or multiply by 2-4). Adding the results of the shifted values provides the temperature data in decimal format, see Equation 5-1. BYTES TO TEMPERATURE CONVERSION Temperature 0°C 4 –4 T A = UpperByte 2 + LowerByte 2 Temperature 0°C 4 –4 T A = UpperByte 2 + LowerByte 2 – 256 Where: TA = Ambient Temperature (°C) UpperByte = TA bit 15 to bit 8 LowerByte = TA bit 7 to bit 0 The temperature bits are in two’s compliment format; therefore, positive temperature data and negative temperature data are computed differently. Equation 5-1 shows the temperature computation. The example instruction code outlined in Figure 5-6 shows the communication flow. Additionally, refer to Figure 5-7 for the timing diagram. This example routine assumes the variables and I2C™ communication subroutines are predefined: i2c_start(); // send START command i2c_write(AddressByte & 0xFE); //WRITE Command //also, make sure bit 0 is cleared ‘0’ i2c_write(0x05); // Write TA Register Address i2c_start(); //Repeat START i2c_write(AddressByte | 0x01); // READ Command //also, make sure bit 0 is Set ‘1’ UpperByte = i2c_read(ACK); // READ 8 bits //and Send ACK bit LowerByte = i2c_read(NAK); // READ 8 bits //and Send NAK bit i2c_stop(); // send STOP command //Convert the temperature data //First Check flag bits if ((UpperByte & 0x80) == 0x80){ //TA TCRIT } if ((UpperByte & 0x40) == 0x40){ //TA TUPPER } if ((UpperByte & 0x20) == 0x20){ //TA TLOWER } UpperByte = UpperByte & 0x1F; //Clear flag bits if ((UpperByte & 0x10) == 0x10){ //TA 0°C UpperByte = UpperByte & 0x0F; //Clear SIGN Temperature = (UpperByte x 16 + LowerByte / 16) - 256; //TA 0°C }else Temperature = (UpperByte x 16 + LowerByte / 16); //Temperature = Ambient Temperature (°C) FIGURE 5-6: DS20005192B-page 22 Example Instruction Code. 2013 Microchip Technology Inc. MCP9844 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 SDA It is not necessary to select the Register Pointer if it was set from the previous read/ write. Note: SCL S 0 0 1 A 2 1 A 1 A A 0 W C K 0 0 0 Address Byte 0 0 1 0 A C K 1 TA Pointer MCP9844 MCP9844 1 2 3 4 5 6 7 8 0 0 1 1 A 2 A 1 A 0 R C 1 2 3 4 5 6 7 8 0 0 0 0 0 0 0 1 1 2 3 4 5 6 7 8 1 0 0 1 0 1 0 0 SCL SDA S A K Address Byte MCP9844 A C K N A K P LSB Data MSB Data Master Master FIGURE 5-7: Timing Diagram for Reading +25.25°C Temperature from the TA Register (See Section 4.0 “Serial Communication”). 2013 Microchip Technology Inc. DS20005192B-page 23 MCP9844 5.1.5 MANUFACTURER ID REGISTER This register is used to identify the manufacturer of the device in order to perform manufacturer specific operations. The Manufacturer ID for the MCP9844 is 0x0054 (hexadecimal). MANUFACTURER ID REGISTER (READ-ONLY) ADDRESS ‘0000 0110’b REGISTER 5-6: R-0 R-0 R-0 R-0 R-0 R-0 R-0 R-0 Manufacturer ID bit 15 bit 8 R-0 R-1 R-0 R-1 R-0 R-1 R-0 R-0 Manufacturer ID bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ -n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared bit 15-0 x = Bit is unknown Device Manufacturer Identification Number . 1 2 3 4 5 6 7 8 0 0 1 1 A 2 A 1 A 0 W C K 1 2 3 4 5 6 7 8 SDA S 0 0 0 0 0 1 1 0 A Address Byte It is not necessary to select the Register Pointer if it was set from the previous read/ write. Note: SCL A C K Manuf. ID Pointer MCP9844 MCP9844 1 2 3 4 5 6 7 8 0 0 1 1 A 2 A 1 A 0 R C 1 2 3 4 5 6 7 8 0 0 0 0 0 0 0 0 1 2 3 4 5 6 7 8 0 1 0 1 0 1 0 0 SCL SDA S A K Address Byte MCP9844 A C K N A K P LSB Data MSB Data Master Master FIGURE 5-8: Timing Diagram for Reading the Manufacturer ID Register (See Section 4.0 “Serial Communication”). DS20005192B-page 24 2013 Microchip Technology Inc. MCP9844 5.1.6 DEVICE ID AND REVISION REGISTER The Device ID and Revision register located at Address Pointer 0x08 is used to identify Microchip devices. The upper byte of these registers is used to specify the device identification and the lower byte is used to specify device silicon revision. The device ID for the MCP9844 is 0x06 (hex). The revision (Lower Byte) begins with 0x00 (hex) for the first release, with the number being incremented as revised versions are released. REGISTER 5-7: R-0 TSE2004AV DEVICE ID AND DEVICE REVISION (READ-ONLY) ADDRESS ‘0000 0111’b AND ‘0000 1000’b R-0 R-0 R-0 R-0 R-1 R-1 R-0 Device ID bit 15 bit 8 R-0 R-0 R-0 R-0 R-0 R-0 R-0 R-1 Device Revision bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ -n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared bit 15-8 Device ID: Bit 15 to bit 8 are used for device ID bit 7-0 Device Revision: Bit 7 to bit 0 are used for device revision 2013 Microchip Technology Inc. x = Bit is unknown DS20005192B-page 25 MCP9844 5.1.7 RESOLUTION REGISTER Note: This register allows the user to change the sensor resolution (see Section 5.2.4 “Temperature Resolution”). The POR default resolution is 0.25°C. The selected resolution is also reflected in the Capability register (see Register 5-2). REGISTER 5-8: R/W-0 In order to prevent accidentally writing the resolution register to a higher resolution and exceeding the maximum temperature conversion time of tCONV = 125 ms, a Shutdown command (using the CONFIG register) is required to change the resolution register. The device must be in Shutdown mode to change the resolution. RESOLUTION REGISTER ‘0000 1001’b U-0 U-0 U-0 U-0 U-0 U-0 U-0 — bit 15 bit 8 U-0 U-0 U-0 U-0 U-0 U-0 R/W-0 R/W-1 Resolution bit 7 bit 0 Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ -n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared bit 15 Unimplemented: Read as ‘0’ bit 14-2 Unimplemented: Read as ‘0’ bit 1-0 Resolution: 00 = LSb = 0.5°C (tCONV = 30 ms, typical) 01 = LSb = 0.25°C (power-up default, tCONV = 65 ms, typical) 10 = LSb = 0.125°C (tCONV = 130 ms, typical) 11 = LSb = 0.0625°C (tCONV = 260 ms, typical) DS20005192B-page 26 x = Bit is unknown 2013 Microchip Technology Inc. MCP9844 5.2 5.2.1 SENSOR FEATURE DESCRIPTION SHUTDOWN MODE Shutdown mode disables all power-consuming activities (including temperature sampling operations) while leaving the serial interface active. This mode is selected by setting bit 8 of CONFIG to ‘1’. In this mode, the device consumes ISHDN. It remains in this mode until bit 8 is cleared ‘0’ to enable Continuous Conversion mode, or until power is recycled. When the ambient temperature increases above the critical temperature limit, the event output is forced to a comparator output (regardless of bit 0 of CONFIG). When the temperature drifts below the critical temperature limit minus hysteresis, the event output automatically returns to the state specified by bit 0 of CONFIG. The status of the event output can be read using bit 4 of CONFIG (Event status). This bit can not be set to ‘1’ in Shutdown mode. The Shutdown bit (bit 8) cannot be set to ‘1’ while bits 6 and 7 of CONFIG (Lock bits) are set to ‘1’. However, it can be cleared ‘0’ or returned to Continuous Conversion while locked. Bit 7 and 6 of the CONFIG register can be used to lock the TUPPER, TLOWER and TCRIT registers. The bits prevent false triggers at the event output due to an accidental rewrite to these registers. In Shutdown mode, all registers can be read or written. However, the serial bus activity increases the shutdown current. The event output can also be used as a critical temperature output using bit 2 of CONFIG (critical output only). When this feature is selected, the event output becomes a comparator output. In this mode, the interrupt output configuration (bit 0 of CONFIG) is ignored. If the device is shutdown while the Event pin is asserted, then the event output will be deasserted during shutdown. It will remain deasserted until the device is enabled for normal operation. Once the device is enabled, it takes tCONV before the device reasserts the event output. 5.2.2 TEMPERATURE HYSTERESIS (THYST) A hysteresis of 0°C, 1.5°C, 3°C or 6°C can be selected for the TUPPER, TLOWER and TCRIT temperate boundaries using bits 10 and 9 of CONFIG. The hysteresis applies for decreasing temperature only (hot to cold), or as temperature drifts below the specified limit. The hysteresis bits can not be changed if either of the lock bits, bits 6 and 7 of CONFIG, are set to ‘1’. The TUPPER, TLOWER and TCRIT boundary conditions are described graphically in Figure 5-9. 5.2.3 EVENT OUTPUT CONFIGURATION The event output can be enabled using bit 3 of CONFIG (Event Output Control bit) and can be configured as either a comparator output or as Interrupt Output mode using bit 0 of CONFIG (Event mode). The polarity can also be specified as an active-high or active-low using bit 1 of CONFIG (event polarity). The event output requires a pull-up resistor to function. These configurations are designed to serve processors with low-to-high or high-to-low edge triggered inputs. With active-high configuration, when the event output deasserts, power will be dissipated across the pull-up resistor. 2013 Microchip Technology Inc. DS20005192B-page 27 MCP9844 5.2.3.1 Comparator Mode Comparator mode is selected using bit 0 of CONFIG. In this mode, the event output is asserted as active-high or active-low using bit 1 of CONFIG. Figure 5-9 shows the conditions that toggle the event output. If the device enters Shutdown mode with asserted event output, the output will deassert. It will remain deasserted until the device enters Continuous Conversion mode and after the first temperature conversion is completed, tCONV. After the initial temperature conversion, TA must satisfy the TUPPER or TLOWER boundary conditions in order for event output to be asserted. Comparator mode is useful for thermostat type applications, such as turning on a cooling fan or triggering a system shutdown when the temperature exceeds a safe operating range. 5.2.3.2 Interrupt Mode In Interrupt mode, the event output is asserted as activehigh or active-low (depending on the polarity configuration) when TA drifts above or below TUPPER and TLOWER limits. The output is deasserted by setting bit 5 (Interrupt Clear) of CONFIG. If the device enters Shutdown mode with asserted event output, the output will deassert. It will remain deasserted until the device enters Continuous Conversion mode and after the first temperature conversion is completed, tCONV. If the interrupt clear bit (bit 5) is never set, then the event output will reassert after the first temperature conversion. 5.2.4 TEMPERATURE RESOLUTION The MCP9844 device is capable of providing temperature data with 0.5°C to 0.0625°C resolution. The resolution can be selected using the Resolution register (Register 5-8), which is located in address ‘00001001’b. This address location is not specified in JEDEC Standard JC42.4. However, it provides additional flexibility while being functionally compatible with JC42.4 and provides a 0.25°C resolution at 125 ms (max.). In order to prevent accidentally changing the resolution and exceeding the 125 ms conversion time, the device must be in Shutdown mode to change this register. The selected resolution can be read by the user using bit 4 and bit 3 of the Capability register (Register 5-2). A 0.25°C resolution is set as POR default by the factory. TABLE 5-2: TEMPERATURE CONVERSION TIME Resolution tCONV (ms) Samples/sec (typical) 0.5°C 30 33 0.25°C (Power-up default) 65 15 0.125°C 130 8 0.0625°C 260 4 In addition, if TA >= TCRIT, the event output is forced as Comparator mode and asserts until TA < TCRIT - THYST. While the event output is asserted, the user must send a Clear Interrupt command (bit 5 of CONFIG) for the event output to deassert when the temperature drops below the critical limit, TA < TCRIT - THYST. Otherwise, the event output remains asserted (see Figure 5-9 for a graphical description). Switching from Interrupt mode to Comparator mode also deasserts event output. This mode is designed for interrupt driven microcontrollerbased systems. The microcontroller receiving the interrupt will have to acknowledge the interrupt by setting bit 5 of the CONFIG register from the MCP9844. DS20005192B-page 28 2013 Microchip Technology Inc. MCP9844 TCRIT - THYST TCRIT TUPPER - THYST TUPPER - THYST TUPPER TA TLOWER - THYST TLOWER TLOWER -THYST (Active-Low) Event Output Comparator Interrupt S/w Int. Clear Critical Only (Active-High) Event Output Comparator Interrupt S/w Int. Clear Critical Only 2 Note: 1 TABLE 5-9: 3 5 6 7 4 2 TEMPERATURE EVENT OUTPUT CONDITIONS Comparator Note 4 1 3 Interrupt Critical TA Bits Output Boundary Conditions Output State (Active Low/High) 15 14 13 1 TA TLOWER High/Low Low/High High/Low 0 0 0 2 TA TLOWER - THYST TA TUPPER Low/High Low/High High/Low 0 0 1 Low/High Low/High High/Low 0 1 0 TA TUPPER - THYST TA TCRIT High/Low Low/High High/Low 0 0 0 Low/High Low/High Low/High 1 1 0 3 4 5 6 When TA TCRIT, the event output is forced to Comparator mode and bits 0 of CONFIG (Event Output mode) is ignored until TA TCRIT - THYST. In Interrupt mode, if Interrupt is not cleared (bits 5 of CONFIG) as shown in the diagram at Note 6, then the event will remain asserted at Note 7 until the Interrupt is cleared by the controller. 7 FIGURE 5-9: TA TCRIT - THYST Low/High High/Low High/Low 0 1 0 Event Output Condition. 2013 Microchip Technology Inc. DS20005192B-page 29 MCP9844 5.3 Summary of Power-on Default The MCP9844 has an internal Power-On Reset (POR) circuit. If the power supply voltage VDD glitches down to the VPOR_TS and VPOR_EE thresholds, the device resets the registers to the power-on default settings. Table 5-3 shows the power-on default summary for the temperature sensor. TABLE 5-3: MCP9844 TEMPERATURE SENSOR POWER-ON RESET DEFAULTS Registers Address (Hexadecimal) Register Name Default Register Data (Hexadecimal) Power-Up Default Register Description 0x00 Capability 0x00EF Event output deasserts in shutdown I2C™ time out 25 ms to 35 ms. Accepts VHV at A0 Pin 0.25°C Measurement Resolution Measures temperature below 0°C ±1°C accuracy over active range Temperature event output 0x01 CONFIG 0x0000 Comparator mode Active-Low output Event and critical output Output disabled Event not asserted Interrupt cleared Event limits unlocked Critical limit unlocked Continuous conversion 0°C Hysteresis 0x02 TUPPER 0x0000 0°C 0x03 TLOWER 0x0000 0°C 0x04 TCRIT 0x0000 0°C 0x05 TA 0x0000 0°C 0x06 Manufacturer ID 0x0054 — 0x07 Reserved 0x0601 — 0x08 Microchip Device ID/ Device Revision 0x0601 — 0x09 Resolution 0x0001 Most Significant bit is set by default 0.25°C Measurement Resolution DS20005192B-page 30 2013 Microchip Technology Inc. MCP9844 6.0 APPLICATIONS INFORMATION 6.1 Layout Considerations 6.2 Thermal Considerations A potential for self-heating errors can exist if the MCP9844 SDA, SCLK and event lines are heavily loaded with pull-ups (high current). Typically, the selfheating error is negligible because of the relatively small current consumption of the MCP9844. A temperature accuracy error of approximately 0.5°C could result from self-heating if the communication pins sink/source the maximum current specified. The MCP9844 device does not require any additional components besides the master controller in order to measure temperature. However, it is recommended that a decoupling capacitor of 0.1 µF to 1 µF be used between the VDD and GND pins. A high-frequency ceramic capacitor is recommended. It is necessary for the capacitor to be located as close as possible to the power and ground pins of the device in order to provide effective noise protection. For example, if the event output is loaded to maximum IOL, Equation 6-1 can be used to determine the effect of self-heating. In addition, good PCB layout is key for better thermal conduction from the PCB temperature to the sensor die. For good temperature sensitivity, add a ground layer under the device pins as shown in Figure 6-1. EQUATION 6-1: EFFECT OF SELFHEATING T = JA V DD I DD + V OL_Event I OL_Event + V OL_SDA I OL_SDA Where: T = TJ - TA TJ = Junction Temperature TA = Ambient Temperature JA = Package Thermal Resistance VOL_Event, SDA = Event and SDA Output VOL (0.4 Vmax) IOL_Event, SDA = Event and SDA Output IOL (3 mAmax and 20 mAmax, respectively) At room temperature (TA = +25°C) with maximum IDD = 500 µA and VDD = 3.6V, the self-heating due to power dissipation T is 0.58°C for the TDFN-8 package. VDD A0 Event A1 EP9 FIGURE 6-1: A2 SCL GND SDA TDFN Package Layout. 2013 Microchip Technology Inc. DS20005192B-page 31 MCP9844 7.0 PACKAGING INFORMATION 7.1 Package Marking Information Example: 8-Lead TDFN (2x3) (MCP9844) Part Number MCP9844T-BE/MNY Code ABS ABS 310 25 Legend: XX...X Y YY WW NNN e3 * Note: DS20005192B-page 32 Customer-specific information Year code (last digit of calendar year) Year code (last 2 digits of calendar year) Week code (week of January 1 is week ‘01’) Alphanumeric traceability code Pb-free JEDEC® designator for Matte Tin (Sn) This package is Pb-free. The Pb-free JEDEC designator ( e3 ) can be found on the outer packaging for this package. In the event the full Microchip part number cannot be marked on one line, it will be carried over to the next line, thus limiting the number of available characters for customer-specific information. 2013 Microchip Technology Inc. MCP9844 Note: For the most current package drawings, please see the Microchip Packaging Specification located at http://www.microchip.com/packaging 2013 Microchip Technology Inc. DS20005192B-page 33 MCP9844 Note: For the most current package drawings, please see the Microchip Packaging Specification located at http://www.microchip.com/packaging DS20005192B-page 34 2013 Microchip Technology Inc. MCP9844 !""#$%&' ( ! "#$%&"'"" ($) % *++&&&! !+$ 2013 Microchip Technology Inc. DS20005192B-page 35 MCP9844 APPENDIX A: REVISION HISTORY Revision B (July 2014) The following is the list of modifications. 1. 2. 3. Updated the Serial Interface Timing Specifications section to include 400 kHz operation from 1.7V to 3.6V. Updated the Temperature Sensor DC Characteristics table. Updated verbiage throughout the document. Revision A (March 2013) • Original Release of this Document. DS20005192B-page 36 2013 Microchip Technology Inc. MCP9844 PRODUCT IDENTIFICATION SYSTEM To order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office. PART NO. -X /XX Device Temperature Range Package Examples: a) Device: MCP9844T: Temperature Range: E Package: MNY* = Plastic Dual Flat, No Lead, (2x3 TDFN), 8-lead (TDFN) MCP9844T-BE/MNY: Tape and Reel, Extended temp., 8LD 2x3 TDFN pkg. Temperature Sensor = -40°C to +125°C (Extended) * Y = Nickel palladium gold manufacturing designator. Only available on the TDFN package. 2013 Microchip Technology Inc. DS20005192B-page 37 MCP9844 NOTES: DS20005192B-page 38 2013 Microchip Technology Inc. Note the following details of the code protection feature on Microchip devices: • Microchip products meet the specification contained in their particular Microchip Data Sheet. • Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the intended manner and under normal conditions. • There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data Sheets. Most likely, the person doing so is engaged in theft of intellectual property. • Microchip is willing to work with the customer who is concerned about the integrity of their code. • Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not mean that we are guaranteeing the product as “unbreakable.” Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our products. Attempts to break Microchip’s code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act. Information contained in this publication regarding device applications and the like is provided only for your convenience and may be superseded by updates. It is your responsibility to ensure that your application meets with your specifications. MICROCHIP MAKES NO REPRESENTATIONS OR WARRANTIES OF ANY KIND WHETHER EXPRESS OR IMPLIED, WRITTEN OR ORAL, STATUTORY OR OTHERWISE, RELATED TO THE INFORMATION, INCLUDING BUT NOT LIMITED TO ITS CONDITION, QUALITY, PERFORMANCE, MERCHANTABILITY OR FITNESS FOR PURPOSE. Microchip disclaims all liability arising from this information and its use. Use of Microchip devices in life support and/or safety applications is entirely at the buyer’s risk, and the buyer agrees to defend, indemnify and hold harmless Microchip from any and all damages, claims, suits, or expenses resulting from such use. No licenses are conveyed, implicitly or otherwise, under any Microchip intellectual property rights. Trademarks The Microchip name and logo, the Microchip logo, dsPIC, FlashFlex, flexPWR, JukeBlox, KEELOQ, KEELOQ logo, Kleer, LANCheck, MediaLB, MOST, MOST logo, MPLAB, OptoLyzer, PIC, PICSTART, PIC32 logo, RightTouch, SpyNIC, SST, SST Logo, SuperFlash and UNI/O are registered trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. The Embedded Control Solutions Company and mTouch are registered trademarks of Microchip Technology Incorporated in the U.S.A. Analog-for-the-Digital Age, BodyCom, chipKIT, chipKIT logo, CodeGuard, dsPICDEM, dsPICDEM.net, ECAN, In-Circuit Serial Programming, ICSP, Inter-Chip Connectivity, KleerNet, KleerNet logo, MiWi, MPASM, MPF, MPLAB Certified logo, MPLIB, MPLINK, MultiTRAK, NetDetach, Omniscient Code Generation, PICDEM, PICDEM.net, PICkit, PICtail, RightTouch logo, REAL ICE, SQI, Serial Quad I/O, Total Endurance, TSHARC, USBCheck, VariSense, ViewSpan, WiperLock, Wireless DNA, and ZENA are trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. SQTP is a service mark of Microchip Technology Incorporated in the U.S.A. Silicon Storage Technology is a registered trademark of Microchip Technology Inc. in other countries. GestIC is a registered trademarks of Microchip Technology Germany II GmbH & Co. KG, a subsidiary of Microchip Technology Inc., in other countries. All other trademarks mentioned herein are property of their respective companies. © 2013-2014, Microchip Technology Incorporated, Printed in the U.S.A., All Rights Reserved. ISBN: 978-1-63276-397-6 QUALITY MANAGEMENT SYSTEM CERTIFIED BY DNV == ISO/TS 16949 == 2013-2014 Microchip Technology Inc. Microchip received ISO/TS-16949:2009 certification for its worldwide headquarters, design and wafer fabrication facilities in Chandler and Tempe, Arizona; Gresham, Oregon and design centers in California and India. The Company’s quality system processes and procedures are for its PIC® MCUs and dsPIC® DSCs, KEELOQ® code hopping devices, Serial EEPROMs, microperipherals, nonvolatile memory and analog products. In addition, Microchip’s quality system for the design and manufacture of development systems is ISO 9001:2000 certified. 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