3 Description. The UCA/A series of pulse width modulator integrated circuits are designed to offer improved performance and lowered external parts. SG – SG Regulating Pulse Width Modulator IC Datasheet – Buy SG Technical Information – STMicroelectronics SG Datasheet. IC. Collector Leakage. VC = 35 V. µA tr*. Rise Time. CL = 1 nF, Tj = 25 ° C. ns tf*. Fall Time. CL = 1 nF, Tj = 25 °C.

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This can eliminate ringing and spurious oscillations that you might get from instantaneous feedback.

Using the UC pulse width modulator | Details |

For other circuits, simply generate 5. The UC supplies a precision 5. You can dahasheet the UC logic from a high voltage input, 35 volts for example, while switching a lower voltage more appropriate for the FETs.

The rise time of the oscillator is determined by Rt, but the fall time is determined by the sum of Rt and Rd. The datasheet for these chips contains almost no application information. A single resistor between the C T and the discharge terminals provide a wide range of dead eg3525 ad- justment.

If you don’t need dead time, short the “Discharge” pin directly to Ct, making Rd effectively zero.


A larger error results in a higher reference voltage, which clips the triangle wave higher, which makes the output pulses narrower, which generates less output, which in turn generates a lower error voltage. The Rd in the UC oscillator section allows the user to set a dead time. The end result is that there is a short time when both pulses are “off” at the same time. Product is under characterization.

Datasheeet the circuit below, the PWM error adjustment is delayed by the RC constant of the amplifier feedback. Clock pulses on a slave nSync prematurely cycle the oscillator flip-flop – causing the peaks and troughs to synchronize with the master.

Triangle wave oscillator So a natural question to ask is: If you don’t need to synchronize multiple units, just leave the nSync and OscOut pins unconnected.

Using the UC3525 pulse width modulator

datwsheet A shutdown terminal controls both the soft-start circuity and the output stages, providing instantaneous turn off through the PWM latch with pulsed shutdown,as well as soft-start recycle with longer shutdown commands. No commitment taken to design or produce NRND: With all these features there’s a lot going on in this one chip, but it’s mostly passives programming the individual sections.

The voltage will shorten or lengthen the PWM times, forcing the output to exactly 12 volts.

Computers and Peripherals Data Center. Once a PWM pulses has been terminated for any reason,the outputs will remain off for the duration of the period. The UC dafasheet is itself a totem-pole: You can also use the op-amp to slow down the feedback.


SG Datasheet(PDF) – Motorola, Inc

Other factors also come into play, such as the lead and trace inductance. To synchronize two devices, set the “master” device to oscillate at the desired frequency, set slave to oscillate a little slower for example: Yes, delete it Cancel. The UC catasheet operates anywhere from 8 to 35 volts. The output stages are totem-pole designs capable of sourcing or sinking in excess of mA.

If you don’t understand something here, take a look at Tahmid’s blog for a counterpoint explanation. An example from Tahmid’s blog: The output voltage comes from a supply separate from the internal chip logic, so you can interface the PWM sections with low-voltage logic while switching a much higher voltage. Any properly-scaled voltage proportional to output error can be used as a reference voltage to the comparator.

If you don’t have need for separate voltage levels, just connect Vc and Vcc together. Usually this ends up burning out your vary-expensive output transistors.