Data Sheet

MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
START, REPEATED START, STOP, ACK, and NACK bits. The PEC is a CRC-8 with polynomial
X8+X2+X1+1. The Most Significant Bit of every byte is transferred first.
8.4.3.1.1 Read Word (depending on the command – RAM or EEPROM)
Figure 5: SMBus read word format
………..
………..
8 1 1 8181
1 1 7117 1 1 81
A A PECAData Byte High P Data Byte Low
Slave Address
Wr
Command
Rd A Slave Address SrAA S
8.4.3.1.2 Write Word (depending on the command – RAM or EEPROM)
Figure 6: SMBus write word format
………..
………..
8 1 1 8181
1811 7 1
A A PECAData Byte High P Data Byte Low
Slave Address
Command
AAWrS
8.4.4 AC specification for SMBus
8.4.4.1 Timing
The MLX90614 meets all the timing specifications of the SMBus [1]. The maximum frequency of the
MLX90614 SMBus is 100 KHz and the minimum is 10 KHz.
The specific timings in MLX90614’s SMBus are:
SMBus Request (t
REQ
) is the time that the SCL should be forced low in order to switch MLX90614 from PWM
mode to SMBus mode;
Timeout L
is the maximum allowed time for SCL to be low. After this time the MLX90614 will reset its
communication block and will be ready for new communication;
Timeout H
is the maximum time for which it is allowed for SCL to be high during communication. After this
time MLX90614 will reset its communication block assuming that the bus is idle (according to the SMBus
specification).
Tsuac(SD)
is the time after the eighth falling edge of SCL that MLX90614 will force PWM/SDA low to
acknowledge the last received byte.
Thdac(SD)
is the time after the ninth falling edge of SCL that MLX90614 will release the PWM/SDA (so the
MD can continue with the communication).
Tsuac(MD)
is the time after the eighth falling edge of SCL that MLX90614 will release PWM/SDA (so that the
MD can acknowledge the last received byte).
3901090614 Page 16 of 42 Data Sheet
Rev 004 30/Jul2008