Dual Universal Hardware Driver for Embedded Systems

Petre Tzv. Petrov Sofia, Bulgaria



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The embedded systems should drive different peripheral devices requiring significant electrical power.

A typical case is the DC motors, operating from 6V, 12V and 24V.


These motors may require up to 3A average current and much more peak current.

It is safer and cheaper to use transistorized drivers for these purposes.

Power transistors are cheap, more difficult to damage and easier to replace if damaged compared to the most integrated circuits – drivers with the same parameters.

That short paper is presented dual universal hardware driver for embedded systems with many applications.

The circuit can be controlled by TTL/CMOS signals produced by most of the MCUs, MPUs and peripheral integrated circuits.

Description of the circuit

Figure 1 is showing the circuit of dual universal hardware driver for embedded systems.
The circuit has two identical channels built around Darlington transistors T1 to T4.

We may use large variety of transistors, e.g. TIP122 and TIP127.

Also we may use ordinary bipolar transistors as BD135/BD136, TIP41/42, etc but the maximal output current is limited to around 0.5A.


Both channels of the driver can work independently, in parallel and in bridge configuration.

The driver has five output connectors CON1 to CON5 and they can be used to drive large variety of loads.

The input control signals for the dual driver are S1, /S2, S3 and /S4.

The signal S1 is controlling the transistor T1, /S2 is controlling transistor T2, S3 is controlling transistor T3, and /S4 is controlling transistor T4.

The active levels of S1 and S3 are HIGH and the active levels of /S2 and /S4 are LOW!

RFID based Attendance System

The LEDs D1 to D4 are showing the status of the control signals and the transitors.

The LED1 is ON when the transistor T1 is ON.
The LED2 is ON when the transistor T2 is ON.
The LED3 is ON when the transistor T3 is ON.
The LED4 is ON when the transistor T4 is ON.

There is no limit for the lowest frequency of switching the transistors T1 to T4.

We may do the control manually with electrical switches controlling S1 to S4.

The maximal switching frequency is limited by transistors and the loads and can be more than 20kHz.