UDN2540B

The UDN2540B has the following features including 1.8 A Continuous Output Current;Output Voltage to 50 V;TTL and 5 V CMOS Compatible Inputs;Efficient Input/Output Pinning;Integral Transient-Suppression Diodes;Replaces L6221 A and L6221 CD.

Combining AND logic gates and inverting high-current bipolar outputs, the UDN2540B and A2540SLB quad Darlington power drivers provide interface between low-level signal-processing circuits and power loads totaling 360 W.  Each of the four independent outputs can sink up to 1 .8 A in the ON state with peak inrush currents to 2.5 A.The four power outputs are each comprised of an open-collector Darlington driver and an internal flyback/clamp diode for switching inductive leads. They feature a minimum breakdown and sustaining voltage of 50 V. The logic inputs are compatible with TTL and 5 V CMOS logic systems.Typical applications include print heads, relays, solenoids, and do stepping motors. These drivers can also be used to drive high-current incandescent lamps, LEDS, and heaters. A similar device,specifically intended for driving a unipolar stepper motor in the two-phase drive format, is the UDN2544B.The UDN2540B is supplied in a 16-pin batwing power DIP; the A2540SLB is supplied in a 20-lead batwing power SOIC for surfacemount applications. The batwing construction provides for maximum package power dissipation in a standard construction. At 250C, and with only 1 sq. in. of copper foil at the ground tabs, either package is capable of safely dissipating more than 2 W.

A typical application is shown for driving four high-current relays,solenoids, or print heads. A Zener diode is used to increase the flyback voltage, providing a much faster inductive load turn-OFF current decay, resulting in faster dropout (reduced relay contact arcing), and improved performance. The maximum Zener voltage, plus the load supply voltage, plus the flyback diode forward voltage must not exceed the device's rated sustaining voltage.With external control circuitry, the ENABLE input can be used for chopper (PWM) applications. If the ENABLE input is not used, it should be tied high.Allegro Microsystems, Inc. reserves the right to make, from time to time, such departures detail specifications as may be required to permit improvements in the design of its products.