Description

The ULN2003A has long been a popular device used for driving high-current peripheral circuits from microcontroller and control logic output signals. The ULN2003A consists of seven Darlington bipolar transistors which sink current from the output to ground when a high logic signal is placed on the input. Because the ULN2003A is based on bipolar Darlington transistor topology, it dissipates a considerable amount of power even when it sinks small output currents.

The TPL7407L is a new peripheral driver that uses an N-channel MOSFET transistor on the output instead of the bipolar Darlington pair. Because of the NMOS output, the TPL7407L can sink more current to ground while dissipating less power and generating less heat which makes it an overall improved device compared to the ULN2003A. This application note explains how the CMOS technology in the TPL7407L improves power dissipation and thermal performance compared to the ULN2003A, including a 50% reduction in power consumption in typical use cases.