EVB90615 Datasheet, PDF (13/30 Pages) Melexis Microelectronic Systems – Infra Red Thermometer

8.4.3.1.2 Write Word (EEPROM only)
MLX90615
Infra Red Thermometer
1
7
S Slave Address
11
Wr A
8
Command
1
A ………..
8
1
8
1
……….. Data Byte Low A Data Byte High A
8
PEC
11
AP
Figure 7: SMBus write word format
Note: Before a write operation takes place, the EEPROM cell needs to be erased. An erase operation is
simply a write of 0000h at the same EEPROM address. Care needs to be taken not to alter factory calibration
(EEPROM addresses 4…Dh).
8.4.4 AC specification for SMBus
8.4.4.1 Timing
The MLX90615 meets all the timing specifications of the SMBus [1] except the values given in the Electrical
specifications section. The maximum frequency of the MLX90615 SMBus clock is 100kHz and the minimum
is 10kHz.
The specific timings for the MLX90615’s SMBus are:
SMBus Request (tREQ ) is the time that the SCL should be forced low in order to switch MLX90615 from
thermal relay mode to SMBus mode;
Timeout L is the maximum allowed time for SCL to be low. After this time the MLX90615 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 MLX90615 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 during which the MLX90615 will force SDA low to
acknowledge the last received byte.
Thdac(SD) is the time after the ninth falling edge of SCL during which the MLX90615 will release the SDA (so
the MD can continue with the communication).
Tsuac(MD) is the time after the eighth falling edge of SCL during which the MLX90615 will release SDA (so
that the MD can acknowledge the last received byte).
Thdac(MD) is the time after the ninth falling edge of SCL during which the MLX90615 will take control of the
SDA (so it can continue with the next byte to transmit).
The indexes MD and SD for the latest timings are used – MD when the master device is making the
acknowledge; SD when the slave device is making the acknowledge). For other timings see [1].
Timeout,L
Tsuac
Thdac
Timeout,H
SCL
3901090615
Rev 001
PWM/SDA
Figure 8: SMBus timing
Page 13 of 30
Data Sheet
28/Aug/2008