Simple Switcher modules simplify power supply design
By Paul Rako, Technical Editor -- EDN, April 1, 2010
 National Semiconductor’s new power modules use a standard IC package for simpler board layout and soldering. |
Devices in National Semiconductor’s new LMZ series of Simple Switcher modules integrate a switching controller, power FETs, and an inductor into one package—a standard configuration with a die-attached-paddle on the bottom, making soldering and assembly of the package more straightforward. The package achieves a thermal junction-to-ambient resistance of 20°/C/W when you mount the device on a 2.25x2.25-in. (5.8x5.8-cm), four-layer board, with 1-oz copper, 36 10-mil thermal vias, and no airflow. The LMZ14203 supports maximum load currents of 3A with an input voltage of 6 to 42V. Other members of the family output 5A with a lower permissible input voltage. Compact design and a shielded inductor allow the parts to comply with EN55022 and CISPR Comité Internationale Spécial des Perturbations Radioelectrotechnique) 22 Class B radiated emission-standard and the EN61000-4-3 industrial standard for radiated immunity.
The parts operate over a –40 to +125°C range and come in a seven-lead, 10.16x13.77x4.57-mm TO-PMOD-7 package. The 5.5V-input LMZ10505TZ 5A costs $7.60, and the 42V-input LMZ14203TZ part costs $9.50 (500). Small quantities are immediately available, and large production orders have six-week leadtimes.
