7/8/2003
Edited by PETech Staff
PWM Controller
Linear Technology’s LT1950 is a Pulse Width Modulator (PWM) controller with a sophisticated control mechanism to protect, simplify, and reduce the size of isolated/non-isolated 15W to 500W power supplies with 24V and 48V input supply rails. It features an adaptive maximum duty cycle clamp circuit to prevent transformer saturation and to protect the MOSFET from catastrophic failures. This feature reduces the transformer size by as much as 50%. Moreover, adjustable current slope compensation allows optimization of transient response with a minimum number of output capacitors. The LT1950's programmable leading edge blanking eliminates the need for current sense filtering. Compared to dc-dc converter modules, the LT1950 solution is smaller, lighter, has lower profile and better airflow, and is significantly lower in cost. Its key applications include power supplies in telecom, industrial, medical, automotive, and aerospace systems where a high reliability isolated/nonisolated power supply rail is used to distribute power within the system.
The LT1950's adaptive maximum duty cycle clamp follows the input voltage so that load and line transients do not cause excessive flux swing in the transformer. Without this feature, designers must use an oversized transformer, larger MOSFETs and extensive filtering. With its adjustable undervoltage lockout (UVLO), the LT1950 can be easily customized to operate with a wide range of input supplies. The operating frequency is adjustable with a resistor from 100kHz to 500kHz. The IC is synchronizable to an external clock while a precision internal reference guarantees an accurate output voltage. It’s packaged in a 16-lead SSOP.
For more information, visit www.linear.com.