MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
The indexes MD and SD for the latest timings are used – MD when the master device is making
acknowledge; SD when the slave device is making acknowledge-. For other timings see [1].
Tsuac
Thdac
Timeout,L
Timeout,H
SCL
PWM/SDA
Figure 7: SMBus timing
8.4.5 Bit transfer
Changing
data
Sampling
data
SCL
PWM/SDA
Figure 8: Bit transfer on SMBus
The data on PWM/SDA must be changed when SCL is low (min 300ns after the falling edge of SCL). The
data is fetched by both MD and SDs on the rising edge of the SCL.
8.4.6 Commands
RAM and EEPROM can be read both with 32x16 sizes. If the RAM is read, the data are divided by two, due
to a sign bit in RAM (for example, TOBJ1 - RAM address 0x07h will sweep between 0x27ADh to 0x7FFF as the
object temperature rises from -70.01°C to +382.19°C). The MSB read from RAM is an error flag (active high)
for the linearized temperatures (TOBJ1, TOBJ2 and Ta). The MSB for the raw data (e.g. IR sensor1 data) is a sign
bit (sign and magnitude format). A write of 0x0000 must be done prior to writing in EEPROM in order to erase
the EEPROM cell content. Refer to EEPROM detailed description for factory calibration EEPROM locations
that need to be kept unaltered.
Opcode
Command
000x xxxx*
001x xxxx*
1111_0000**
1111_1111
RAM Access
EEPROM Access
Read Flags
Enter SLEEP mode
Note*: The xxxxx represent the 5 LSBits of the memory map address to be read/written.
Note**: Behaves like read command. The MLX90614 returns PEC after 16 bits data of which only 4 are
meaningful and if the MD wants it, it can stop the communication after the first byte. The difference between
read and read flags is that the latter does not have a repeated start bit.
Flags read are:
Data[15] – EEBUSY – the previous write/erase EEPROM access is still in progress. High active.
Data[14] – Unused
Data[13] - EE_DEAD – EEPROM double error has occurred. High active.
Data[12] – INIT – POR initialization routine is still ongoing. Low active.
Data[11] – not implemented.
Data[10..0] – all zeros.
Flags read is a diagnostic feature. The MLX90614 can be used regardless of these flags.
3901090614
Rev 003
Page 16 of 40
Data Sheet
03/Oct/2007
MELEXIS [ Melexis Microelectronic Systems ]
