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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Any properly-scaled voltage proportional to output error can be used as a reference voltage to the comparator. No commitment taken to design or produce NRND: For example, high power FETs usually require between 8 and 20 volts for proper switching. The UC implements an extra op-amp on the VRef input of the comparator and brings the connections out to the user.

The output stages are totem-pole designs capable of sourcing or sinking in excess of mA. Product is in volume production only to support customers ongoing production. Sg5325 end result is that there is a short time when both pulses are “off” at the same time.

ST Microelectronics

The rise time of the oscillator is determined by Rt, but the fall time is determined by the sum of Rt and Rd. Once you understand the individual sections, using the UC in a circuit is straightforward. This prevents the device from generating spurious output before other sections of the circuit come on line.

Product is in volume production. The UC output is itself a totem-pole: These devices also feature built-in soft-start circuitry with only an external timing capacitor required. Sign up Already a member? It can give a microcontroller a chance to boot, capacitors a chance to charge, and other control electronics time to start.


A PWM signal is generated by comparing a triangle wave to a reference level. If you don’t understand something here, take a look at Tahmid’s blog for a counterpoint explanation. IoT for Smart Things. Distributor Name Region Stock Min. Using the UC pulse width modulator A project log for Improve the Haber process See if ultrasonic cavitation can be used to datashest atmospheric Nitrogen less expensively than the Haber process.

This is called “shoot through”, and in effect the transistors briefly short the power supply to ground, often with disastrous results. The upshot is that the user sets the oscillation frequency by supplying an R and C to the oscillator section according to the following formula:. Clock pulses on a slave nSync prematurely cycle the oscillator flip-flop – causing the peaks and troughs to synchronize with dataeheet master.

Using the UC3525 pulse width modulator

If you want a sb3525 output, configure the oscillator to run at Hz. If you don’t need dead time, short the “Discharge” pin directly to Ct, making Rd effectively zero. Buy Direct Add to cart.

The Rd in the UC sg352 section allows the user to set a dead time. 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.

ST Microelectronics – datasheet pdf

Please contact our sales support for information on specific devices. No availability reported, please contact our Sales office. Pulse width modulators are common. Conceptually, the gate has a small capacitance and the driver has an internal resistance, so switching the transistor takes an RC constant to complete.

The UC logic operates anywhere from 8 to 35 volts. It’s pretty simple, and can be breadboarded in an afternoon. The circuit doesn’t have to be a power supply, it only needs a feedback voltage proportional to the error.


The extra conductance causes the capacitor to discharge faster than it rises, prematurely ending the pulse a little before the opposite pulse begins. Media Subscription Media Contacts. The UC chip is basically a triangle wave generator and comparator, with some extras thrown in for convenience. Support Center Video Center. The oscillator has a pulse output that can be used to measure the generated frequency, and an input for synchronizing multiple devices. The voltage will shorten or lengthen the PWM times, forcing the output to exactly 12 volts.

If you don’t have need for separate voltage levels, just connect Vc and Vcc together. ST Code of Conduct Blog. The output will be high when the triangle is higher than the reference and low everywhere else. The discharge resistor, Rd is discussed later. The internet isn’t much help either. Support Center Complete list and gateway to support services and resource pools.

Product is in design stage Target: Once you have the basic circuit running, modifying it for your project is straightforward. Then you connect the constant current source to a constant capacitance and the voltage rises linearly as a function of time. The UC provides a constant current source and a flip-flop mechanism that alternately charges and discharges a capacitor which the user supplies.

Tahmid’s blog has a pin-by-pin functional description with a demonstration circuit, and the SGx App Note describes a related chip, but with important differences.