ADM1178 Analog Devices, ADM1178 Datasheet - Page 16

• Manufacturer Part Number: ADM1178
• Description: Hot Swap Controller and Digital Power Monitor with ALERTB Output
• Manufacturer: Analog Devices

Specifications of ADM1178

• Operating Range(v): 3.15 to 16.5
• Uv & Ov Detection: ON pin (UV)
• Digital V & I Readback: I2C Interface,w/ 4 Addreses
• I Monitor Accuracy (+/-%): 2%
• Other Outputs: ALERTB
• Package: 10-Lead MSOP

ADM1178
VOLTAGE AND CURRENT READBACK
In addition to providing hot swap functionality, the ADM1178
contains the components to allow voltage and current readback
over an I
amplifier and the voltage on the VCC pin are fed into a 12-bit
ADC via a multiplexer. The device can be instructed to convert
voltage and/or current at any time during operation via an I
command. When all conversions are complete, the voltage
and/or current values can be read back with 12-bit accuracy in
two or three bytes.
SERIAL BUS INTERFACE
Control of the ADM1178 is carried out via the I
interface is compatible with the I
maximum). The ADM1178 is connected to this bus as a slave
device, under the control of a master device.
IDENTIFYING THE ADM1178 ON THE I
The ADM1178 has a 7-bit serial bus slave address. When the
device powers up, it does so with a default serial bus address.
The three MSBs of the address are set to 111, and the two MSBs
are set to 10, resulting in an address of 111x10. Bit A2 and Bit
A3 are determined by the state of the ADR pin. There are four
configurations available on the ADR pin that correspond to four
I
four ADM1178 devices to operate on a single I
GENERAL I
Figure 35 and Figure 36 show timing diagrams for general write
and read operations using the I
conditions for different types of read and write operations, which
are discussed in the Write and Read Operations section. The
general I
1.
Table 5. Setting I
Base Address
111AA10
1
2
X = don’t care.
C addresses for these bits (see Table 5). This scheme allows
The master initiates a data transfer by establishing a start
condition, defined as a high-to-low transition on the serial
data line, SDA, while the serial clock line, SCL, remains
high. This indicates that a data stream is to follow. All slave
peripherals connected to the serial bus respond to the start
condition and shift in the next eight bits, consisting of a 7-bit
slave address (MSB first) plus an R/ W bit that determines
the direction of the data transfer, that is, whether data is
written to or read from the slave device (0 = write, 1 = read).
2
2
C protocol operates as follows:
C bus. The voltage output of the current sense
2
C TIMING
2
C Addresses via the ADR Pin
ADR Pin State
Ground
Resistor to ground
Floating
High
2
C. The I
2
C fast mode (400 kHz
2
C specification defines
2
2
C bus. This
C bus.
2
C BUS
ADR Pin Logic State
00
01
10
11
2
Rev. C | Page 16 of 24
C
2.
3.
The peripheral whose address corresponds to the transmitted
address responds by pulling the data line low during the low
period before the ninth clock pulse, known as the acknowl-
edge bit, and holding it low during the high period of this
clock pulse. All other devices on the bus remain idle while
the selected device waits for data to be read from it or written
to it. If the R/ W bit is 0, the master writes to the slave device.
If the R/ W bit is 1, the master reads from the slave device.
If the operation is a write operation, the first data byte after
the slave address is a command byte. This tells the slave
device what to expect next. It can be an instruction, such as
telling the slave device to expect a block write, or it can be
a register address that tells the slave where subsequent data
is to be written.
Because data can flow in only one direction, as defined by
the R/ W bit, it is not possible to send a command to a slave
device during a read operation. Before performing a read
operation, it may be necessary to first execute a write
operation to tell the slave what sort of read operation to
expect and/or the address from which data is to be read.
When all data bytes are read or written, stop conditions are
established. In write mode, the master pulls the data line
high during the 10
In read mode, the master device releases the SDA line
during the SCL low period before the ninth clock pulse,
but the slave device does not pull it low. This is known as a
no acknowledge. The master then takes the data line low
during the SCL low period before the 10
then high during the 10
Data is sent over the serial bus in sequences of nine clock
pulses: eight bits of data followed by an acknowledge bit
from the slave device. Data transitions on the data line
must occur during the low period of the clock signal and
remain stable during the high period because a low-to-
high transition when the clock is high can be interpreted as
a stop signal.
Address in Binary
1110010X
1110110X
1111010X
1111110X
th
clock pulse to assert a stop condition.
th
clock pulse to assert a stop condition.
1
Address in Hex
0xE4
0xEC
0xF4
0xFC
th
clock pulse and