UC3638

The UC2638 family of integrated circuits are advanced pulse width modulators intended for a variety of PWM motor drive and amplifier applications requiring either uni-directional or bi-directional drive circuits. Similar in architecture to the UC2637, all necessary circuitry is included to generate an analog error signal and modulate two bi-directional pulse train outputs in proportion to the error signal magnitude and polarity.

Key features of the UC2638 include a programmable high speed triangle oscillator, a 5X differential current sensing amplifier, a high slew rate error amplifier, high speed PWM comparators, and two 50mA open collector as well as two ±500mA totem pole output stages. The individual circuit blocks are designed to provide practical operation to switching frequencies of 500kHz.

Significant improvements in circuit speed, elimination of many external programming components, and the inclusion of a differential current sense amplifier, allow this controller to be specified for higher performance applications, yet maintain the flexibility of the UC2637. The current sense amplifier in conjunction with the error amplifier can be configured for average current feedback. The additional open collector outputs provide a drive signal for the highside switches in a full bridge configuration. The programmable AREFIN pin allows for single or dual supply operation. Oscillator ramp amplitude and PWM deadband are programmable by tapping a voltage divider off the 5V reference to the appropriate programming input (PVSET or DB).

Additional features include a precision externally available 5V reference, undervoltage lockout, pulse-by-pulse peak current limiting, and a remote shutdown port. The UC1638 family is available in the 20 pin N, DW and J packages. Consult the factory for other packaging options.