Pseudo Schottky Output Driver
Original Publication Date: 1986-Sep-01
Included in the Prior Art Database: 2005-Mar-09
A circuit is added to an open collector driver on a chip without any Schottky barrier diodes to enable faster switching without a Schottky diode. In its simplest form, an open collector driver is rather slow acting due to saturation of its transistor so that it cannot be used where the frequency is much greater than 2 MHz. This long turn-off delay of the transistor can be reduced by adding a Schottky diode between the base and collector of the transistor to prevent it from saturating. However, with a chip having no Schottky barrier diodes, this is not available. A chip 1 includes an NPN transistor 2, which must be turned off and on at a frequency of at least 4 MHz and is the transistor of the simplest form open collector driver that saturates. The chip 1 has a constant current source 3 controlled by a switch 4.