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Maxim rolls out PWM controllers for power supplies

Posted: 15 Jun 2004 ?? ?Print Version ?Bookmark and Share

Keywords:maxim integrated products? max5071a? max5071b? pwm controller?

Maxim Integrated Products introduced two high-performance, single-ended, current-mode PWM controllers for isolated telecom dc-dc or universal offline-input ac-dc power supplies.

The MAX5071A and MAX5071B controller ICs are pin compatible with the industry-standard multisourced UC2842/UCC2842 and UC2844/UCC2844 family of products (except that the feedback FB pin is replaced with a bidirectional SYNC input pin), allowing designers to upgrade existing power-supply designs for higher performance with minimal component changes.

The bidirectional synchronization input on the devices allows multiple power supplies to operate at the same frequency. The bidirectional synchronization pin is an input/output pin that outputs synchronizing pulses and can also accept synchronization signals from an external source or from other MAX5071A/MAX5071B devices. The SYNC input pins of multiple MAX5071A/MAX5071B ICs can be connected together, with all devices synchronizing to the device with the highest frequency.

The switching frequency is externally programmable from 20kHz to 1MHz. Additionally, the timing-capacitor discharge current is trimmed to 5 percent. This allows the maximum duty cycle to be set accurately, avoiding transformer saturation. The maximum duty cycles for the MAX5071A and MAX5071B are 100 percent and 50 percent, respectively. The switching frequency is trimmed for 7 percent accuracy while the current-limit threshold and start/stop voltages are trimmed to 5 percent accuracy.

According to Maxim, the devices' 60ns cycle-by-cycle current-limit propagation delay allows a fast response to output short circuit. Startup current is typically 35?A. The PWM controllers' gate-driver outputs are capable of sourcing 2A and sinking 1A. Both devices include overtemperature shutdown.

Rated for operation between the -40C to 125C temperature range, the new products are available in 8-pin SO and 8-pin microMAX packages. Prices start at 61 cents (1,000-up, FOB USA).

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