High-side mosfet load switch driver is 1.2 x 0.8mm

Author: EIS Release Date: Feb 28, 2022

Toshiba has introduced a mosfet load switch gate driver in a 1.2 x 0.8 x 0.35mm 6bump WCSP6G the chip-scale package, suiting it to wearables and smartphones, it said.

 

Toshiba TCK421G highSide gate driver

The IC, called TCK421G, can separately drive the gates of a pair of back-to-back n-channel mosfets to make a reverse-blocking switch – useful when multiplexing power sources.

 

If reverse blocking is not needed, a single mosfet can be used, with its gate connected to VGATE2 (see diagrams).

 

Toshiba TCK421G highSide gate driver appExternal mosfet pairs are connected drain-to-drain, rather than the more usual source-to-source connection (Electronics Weekly has asked why, watch this space), and a charge-pump is included to take the gates ~10V above the 2.7 to 28.0V input voltage (40V abs max) to turn them fully on “thereby facilitating the switching of large currents”, said the company. Examples in the data sheet show it switching up to 3A using

 

Over-voltage and under-voltage lockouts are provides, typically at ~23V and 2V respectively. These are not intended to protect the device or its mosfets from destruction. “Furthermore, Toshiba recommends inserting fail-safe system into the design,” according to the data sheet.

 

Worst case (with Vin = 20V) input quiescent current in the ‘on’ state is 560µA , while worst-case 20Vin ‘off’ state current is 1.3µA. Both can be considerably lower at lower input voltages.

 

Toshiba said this is the first device in a series of six.