Part Number Search

Cross Reference Search

About information presented in this cross reference

The information presented in this cross reference is based on TOSHIBA's selection criteria and should be treated as a suggestion only. Please carefully review the latest versions of all relevant information on the TOSHIBA products, including without limitation data sheets and validate all operating parameters of the TOSHIBA products to ensure that the suggested TOSHIBA products are truly compatible with your design and application.
Please note that this cross reference is based on TOSHIBA's estimate of compatibility with other manufacturers' products, based on other manufacturers' published data, at the time the data was collected.
TOSHIBA is not responsible for any incorrect or incomplete information. Information is subject to change at any time without notice.

Keyword Search

Parametric Search

Stock Check & Purchase

Select Product Categories

Select Application

Find everything you need for your next product design. Simply select an application and click through to the block diagram to discover our semiconductor solutions.

New Products / News

Innovation Centre

At the Toshiba Innovation Centre we constantly strive to inspire you with our technologies and solutions. Discover how to place us at the heart of your innovations.

How to control latching relays in smart power meters - an alternative use for brush motor driver ICs

Magnetic latching relays are key components in today’s smart power meters, where they are used to facilitate the remote disconnection and reconnection of power to the consumer premises. A key benefit of such relays is their low power consumption as they maintain last contact position after the control power has been removed. Turning the relay on and off simply requires a momentary application of a trigger pulse current to the relay coil. A pulse in one direction will set the relay to the first position, and a pulse in the other direction to the second position.

Toshiba TC78H610FNG dual DC H-bridge driver IC

In general, drive circuits for latching relays are more complex than those for other relays. Typically, a half-bridge circuit is needed if dual supply voltages are available, and a full-bridge will be required if just one supply is available. Discrete circuits may be developed for the control of latching relays, but it is increasingly common to employ dedicated driver ICs. Whichever approach an engineer chooses, key design criteria are likely to include minimum circuit size, high-efficiency operation and the implementation of appropriate protection functionality.

Because the requirements for controlling latching relays – bridge circuitry, low-power operation, the need for protection, compact design – are similar to the drive requirements of brushed motors, it is also possible to deploy dedicated motor control driver (MCD) ICs in latching relay control circuitry. What’s more, because many smart meters have two latching relays, and because some motor drive ICs combine dual control with high levels of integrated protection functionality, this approach can help to simplify circuit design and reduce component count.

Take, for example, Toshiba’s TC78H610FNG. Supplied in a compact SSOP 16 package measuring just 5.0mm x 4.4mm, this direct driver IC incorporates two MOSFET-based H-bridges. As a result, it is ideally suited to driving the two single-coil latching relays found in modern smart meters. Electric current direction is easily controlled by the application of appropriate input signals to the IC.

Block diagram of smart meter ‘open/close’ operation circuit using latching relays and motor control driver

Furthermore, because the IC integrates high levels of protection – it has built-in circuitry for over current detection (ISD), thermal shutdown (TSD) and under voltage lockout (UVLO) - the need for additional protection circuitry and components is drastically reduced.

The diagram below illustrates how this MCD can be incorporated into a smart meter’s latching relay circuit, with signals PHA_A and PHA_B being used to control the current to the relays.

To find out more about Toshiba’s comprehensive family of motor control driver ICs, click here.

A new window will open