SE97TP datasheet(6/54 Pages) NXP

6 / 54 page

SE97_5

Product data sheet

Rev. 05 — 6 August 2009

6 of 54

NXP Semiconductors

SE97

DDR memory module temp sensor with integrated SPD, 3.3 V

Functional description

7.1 Serial bus interface

The SE97 communicates with a host controller by means of the 2-wire serial bus

(I2C-bus/SMBus) that consists of a serial clock (SCL) and serial data (SDA) signals. The

device supports SMBus, I2C-bus Standard-mode and Fast-mode. The I2C-bus standard

speed is deﬁned to have bus speeds from 0 Hz to 100 kHz, I2C-bus fast speed from 0 Hz

to 400 kHz, and the SMBus is from 10 kHz to 100 kHz. The host or bus master generates

the SCL signal, and the SE97 uses the SCL signal to receive or send data on the SDA

line. Data transfer is serial, bidirectional, and is one byte at a time with the Most Signiﬁcant

Bit (MSB) is transferred ﬁrst. Since SCL and SDA are open-drain, pull-up resistors must

be installed on these pins.

7.2 Slave address

The SE97 uses a 4-bit ﬁxed and 3-bit programmable (A0, A1 and A2) 7-bit slave address

that allows a total of eight devices to co-exist on the same bus. The A0, A1 and A2 pins

are pulled LOW internally. The A0 pin is also overvoltage tolerant supporting 10 V

software write protect. When it is driven higher than 7.8 V, writing a special command

would put the EEPROM in reversible write protect mode (see Section 7.10.2 “Memory

protection”). Each pin is sampled at the start of each I2C-bus/SMBus access. The

temperature sensor’s ﬁxed address is ‘0011b’. The EEPROM’s ﬁxed address for the

normal EEPROM read/write is ‘1010b’, and for EEPROM software protection command is

‘0110b’. Refer to Figure 6.

a. Temperature sensor

b. EEPROM (normal read/write)

c. EEPROM (software

protection command)

Fig 6.

Slave address

R/W

002aab304

fixed

hardware

selectable

slave address

MSB

LSB

R/W

002aab351

fixed

hardware

selectable

slave address

MSB

LSB

R/W

002aab352

fixed

hardware

selectable

slave address

MSB

LSB

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