ne1618 NXP Semiconductors, ne1618 Datasheet - Page 7

• Manufacturer Part Number: ne1618
• Description: Temperature Monitor For Microprocessor Systems
• Manufacturer: NXP Semiconductors

1. NC = Not Connected.
Philips Semiconductors
FUNCTIONAL DESCRIPTION
Serial bus interface
The NE1618 can be connected to a compatible 2-wire serial
interface System Management Bus (SMBus) as a slave device
under the control of a master device, using two device terminals
SCLK and SDATA. The controller will provide a clock signal to the
device SCLK pin and write/read data to/from the device through the
device SDATA pin. External pull-up resistors, about 10 k each,
are needed for these two terminals due to the open drain circuitry.
Data of 8-bit digital byte or word are used for communication
between the controller and the device using SMBus protocols which
will be described more in the SMBus interface section. The
operation of the device to the bus is described with details in the
following sections.
Slave address
The 7-bit address data of the NE1618 on the bus is defined by
three-level logical connections applied to the device address pins
ADD0 and ADD1. They are either opened or connected directly to
the GND or V
equal to or less than 2 k . The selectable addresses are listed in
Table 1. Any one of those nine combinations can be used for any
device and more than one devices can reside on the same bus
without conflict. Notice that because the state of the device address
pins is sampled and latched not only at the power-up step but also
at starting point of every conversion, the address connections must
be permanently existent.
Table 1. Device slave address
2002 Jan 04
ADD0 pin
GND
GND
GND
NC
NC
NC
V
V
V
DD
DD
DD
Temperature monitor for microprocessor systems
DD
ADD1 pin
GND
NC
V
GND
NC
V
GND
NC
V
with the use of a resistor which value should be
DD
DD
DD
7-BIT ADDRESS DATA
0011 000
0011 001
0011 010
0101 001
0101 010
0101 011
1001 100
1001 101
1001 110
7
Registers
The NE1618 contains a number of registers which names,
commands, power-on reset (POR) status and functions are listed in
Table 2. It includes:
The registers are used to store either programmable data for setting
device operation or resultant data from device measurement. Data
are stored in registers by 8-bit digital byte, either in 2’s complement
format for temperature-related data or in straight format for others.
The register command byte is used to addressing the register in
SMBus communication. Writing and reading registers will be
performed on the SMBus by a controller. The registers are divided
into two groups: only-read registers named with a prefix of R– and
only-write registers named with a prefix of W– (including the
one-shot register OSHT). You should write programmable data to
the only-write registers and read data from the only-read registers.
Attempting to write to any R– register or read from any W– register
will produce an invalid result: the writing data would be ignored, the
reading data would be equal to FFh. Some of registers are in pair
representing a same item for different bus operations: read and
write, for example, RC and WC are related to the device
configuration, one for reading and the other for writing.
The reserved registers are used only at the manufacturer for test
purposes.
Configuration register to provide control and configuration the
NE1618
Status register to provide the flags resulting from temp limit
comparisons
Measuring and limits temp registers
ID and test registers
NE1618
Product data