Document
19-2830; Rev 0; 4/03
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Synchronizable, High-Frequency Current- and Voltage-Mode PWM Controllers for Isolated Supplies
MAX8540/MAX8541
General Description
The MAX8540/MAX8541 pulse-width-modulated (PWM) controllers for forward/flyback isolated DC-to-DC converters provide maximum flexibility to power-supply designers and reduce external component count. These controllers allow common PC board layout for currentmode (MAX8540) and voltage-mode (MAX8541) designs.
Both controllers feature adjustable switching frequency and external synchronization from 200kHz to 1MHz. Active-high and active-low enable, undervoltage protection (UVP), and overvoltage protection (OVP) reduce external component count.
Maximum duty cycle is adjustable, and the feed-forward function scales the maximum duty cycle with input voltage to limit the maximum volt-seconds applied to the transformer primary. The MAX8540 allows the user to select the value of slope compensation to further optimize mag.