Intelligent power switch: Taxes instruments’ TPIC2404 is a monolithic high-voltage, high-current, quadruple loads, such as relays, solenoids, motors, lamps, and other high-voltage, high-current loads from low-level logic. It can switch currents of up to 1 A without any problem: the current may be increased to 4 A by connecting four outputs in parallel. As shown in Fig. 2, the outputs are of the open-collector type.
Connected to a circuit as shown in Fig. 1, the chip may conveniently be used to increase the power handling of the Centronics analog-to-digital and digital-to-analog converter published in the May 1990 issue of Elektor Electronics. Note
that the FAULT output of the IC is connected to input 11 of the converter. This enables the TPIC2404 to indicate the following fault conditions.
• Too high supply voltage (>25.5 V). • Thermal overload. • Output short circuit. • Loads not connected (only if outputs are inactive).
The software regularly monitors the level on line 11 and will indicate a fault condition. The TPIC2404 must be fitted on to a small heatsink: 8 cm2 (1.5 in2). When the chip is used with the converter, R31 on the converter board must be disconnected. The switch draws a current of about 100 mA when all outputs are active.