Browse Prior Art Database

Modular Current Driver

IP.com Disclosure Number: IPCOM000092923D
Original Publication Date: 1967-Mar-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Trinko, JP: AUTHOR

Abstract

The drive current for a core line forming an inductive load L can first be directed through transistor T2 and then be directed through resistor R2. This results in obtaining a fast rise time while at the same time limiting the power dissipation in transistor switch T1 controlling the current through L.

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Modular Current Driver

The drive current for a core line forming an inductive load L can first be directed through transistor T2 and then be directed through resistor R2. This results in obtaining a fast rise time while at the same time limiting the power dissipation in transistor switch T1 controlling the current through L.

T2 is normally conductive when T1 is first switched on by a pulse supplied to the input. Therefore, current initially flows through L, T1, and T2 to drive the cores. With T2 in the circuit, the resistance in the current path is low. Thus the change in current di/dt through the load is initially rapid.

This insures good rise times for fast switching of the cores. However, as the current through the load increases, the voltage across resistor R3 increases turning T3 on and T2 off. This causes the current passing through L to flow through R2. Thus, as the change in current decreases, and, as a result, the voltage across L decreases, power is primarily dissipated across R2. This prevents a high power dissipation condition in T1 for the current driver.

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