Arexx AAR-04, Руководство пользователя, Страница: 20 / 30

- 20 -
The 3V-power supply is an ideal condition for a robot with a battery-
pack of only 2 cells. The PNP-transistors however cannot easily be
integrated in an IC such as the L293D. An IC however has other
advantages such as reliability, protection against bad circuitry and
reduced PCB-area and low weight. For this reason we decided to
use a L293D-chip with a dual H-bridge circuitry to simultaneously
control two DC-motors.
5.2 A H-Bridge for 4,5 Volt
The L293D-chip (see fig. 10) allows us to control output-currents up
to 600mA pro channel (maximal: 1.2A peak currents). The power
supply voltage of the drivers (VCC2) may vary between 4.5V and
36V, which promotes this L293D-Chip to a favorite circuit for DC-
motor control.
The minimal power supply voltage (VCC2) however has been speci-
fied as 4.5V, which forces us to choose a minimum of 4 rechargeable
batteries as a power supply. This investment increases the robot’s
total weight. It is the price we pay for modern electronic circuitry.
Fig. 10 H-Bridge circuitry with
a L293D-Chip