Datasheet

TPS2480

TPS2481

SLUS939B –APRIL 2010–REVISED DECEMBER 2010

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Power, Current, and Voltage Monitoring (PIV)

The TPS2480/81 digital current-shunt monitor has an I

C / SMBus-compatible interface. It provides digital

current, voltage, and power readings for accurate decision-making in precisely-controlled systems.

Programmable registers allow flexible configuration for measurement resolution, and continuous versus-triggered

operation. Detailed register information appears in the Register Information Section. See the Register Block

Diagram for a block diagram of the TPS2480 / 81 PIV monitoring circuits.

PIV Monitoring - Typical Application Circuit Considerations

Figure 17 shows a typical application circuit for the TPS2480/81. 0.1-mF ceramic capacitors must be placed as

close as possible to the supply and ground pins for supply bypassing.

The pull-up resistors shown on the SDA and SCL lines are not needed if there are pull-up resistors on these

same lines elsewhere in the system. Resistor values shown are typical: consult the I

C or SMBus specification to

determine acceptable values.

C Bus Overview

The I

C and SMBus protocols are essentially compatible with each other and the TPS2480/81 are compatible

with both. This allows use of the I

C interface throughout this data sheet as the primary example, with SMBus

protocol specified only when there is a difference.

Two bidirectional lines, SCL and SDA, connect the TPS2480 / 81 to the bus. Both SCL and SDA are open-drain

connections. The device that initiates the transfer is called a master, and the devices controlled by the master

are slaves. The bus must be controlled by a master device that generates the serial clock (SCL), controls, the

bus access, and generates START and STOP conditions.

To address a specific device, the master initiates a START condition by pulling SDA from a HIGH to a LOW logic

level while SCL is HIGH. All slaves on the bus shift in the slave address byte on the rising edge of SCL, with the

last bit indicating whether a read or write operation is intended. During the ninth clock pulse, the slave being

addressed responds to the master by generating an Acknowledge and pulling SDA LOW.

Data transfer is then initiated and eight bits of data are sent, followed by an Acknowledge bit. During data

transfer, SDA must remain stable while SCL is HIGH. Any change in SDA while SCL is HIGH is interpreted as a

START or STOP condition.

Once all data have been transferred, the master generates a STOP condition, indicated by pulling SDA from

LOW to HIGH while SCL is HIGH. The TPS2480/81 includes a 28-ms timeout on its interface to prevent locking

up an SMBus.

Product Folder Link(s): TPS2480 TPS2481