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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ST Microelectronics

About Us Contact Hackaday. General terms and conditions. The power transistors don’t turn off instantly when their controlling pulse goes low, so if the falling and rising edges of the control pulses are close enough, there’s a brief time when both transistors are conducting.

Some have a small section detailing how the “Shutdown” pin can be used to skip a pulse when needed, but others don’t even have that. A single resistor between the C T and the discharge terminals provide a wide range of dead time ad- justment. The circuit doesn’t have to be a power supply, it only needs a feedback voltage proportional sy3525 the error. Please contact our sales support for information on specific devices. Once you understand the individual sections, using the UC in a datasheeh is straightforward.

The voltage will shorten or lengthen the PWM times, forcing the output to exactly 12 volts. There’s very little information on the net that explains how to use these chips, so for this week’s update I thought I’d write a quick summary.

SG Datasheet(PDF) – Motorola, Inc

Adjusting the reference adjusts the pulse width. You can operate the UC logic from a high voltage input, 35 volts for example, while switching a lower voltage more appropriate for the FETs.

As far as I datasneet tell, no one has ever used this feature. Menu Products Explore our product portfolio. Conceptually, the gate has a small capacitance and the driver has an internal resistance, so switching the transistor takes an RC constant to complete.


Any properly-scaled voltage proportional to output error can be used as a reference voltage to the comparator.

There’s also a low-voltage detection that takes the outputs offline when the power is removed – you don’t have to worry about the output going haywire as the control circuitry powers down. It’s pretty simple, and can be breadboarded in an afternoon. The rise time of the oscillator is determined by Rt, but the fall time is determined by the sum of Rt and Rd. Usually this ends up burning out your vary-expensive output transistors.

Marketing proposal for customer feedback. A shutdown terminal controls both the soft-start circuity and the output stages, providing iic turn off through the PWM latch with pulsed shutdown,as well as soft-start recycle with longer shutdown commands. If you don’t understand something here, take a look at Tahmid’s blog for a counterpoint explanation.

Using the UC pulse width modulator A project log for Improve the Haber process See if ultrasonic cavitation can be used to fixate atmospheric Nitrogen less expensively than the Haber process. IoT for Smart Things. If you don’t have need for separate voltage levels, just connect Vc and Vcc together. The SGA series of pulse width modulator integrated circuits are designed to offer improved performance and lowered external parts count when used in designing all types of switching power supplies.

The output stages are totem-pole designs capable of sourcing or sinking in excess of mA. Then you connect the constant current source to a constant capacitance and the voltage rises linearly as a function of time. Product is under characterization. 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.

Selectors Simulators and Models. Once a PWM pulses datasyeet been terminated for any reason,the outputs will remain off for the duration of the period. This is called “shoot through”, and in effect the transistors briefly short the power supply to ground, often with disastrous results. Getting started with eDesignSuite 5: If you want a 50Hz output, configure the oscillator to run at Hz.


Programmable Dead time A “totem pole” output can have problem with synchronous control pulses. The discharge resistor, Rd is discussed later. 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: For example, a 12V power supply might have an error voltage proportional to the difference between 12 volts and the actual output. So for another example, you can make a class-D amplifier using an audio signal as Vref: Not Recommended for New Sg5325.

Putting it all together With all these features there’s a lot going on in this one chip, but it’s mostly passives programming the individual sections.

These functions are also dataasheet by an undervoltage lockout which keeps the outputs off and the soft-start capacitor discharged for sub-normal input voltages.

Limited Engineering samples available Preview: See if ultrasonic cavitation can be used to fixate atmospheric Nitrogen less expensively than the Haber process. The solution is to have “dead time” where both pulses are off during datadheet transitions, giving the active transistor time to turn off before the inactive one turns on.

The Rd in the UC oscillator section allows the user to set a dead time. In the circuit datasyeet, the PWM error adjustment is dwtasheet by the RC constant of the amplifier feedback. Where to get chips Pulse width modulators are common. The UC chip is basically a triangle wave generator and comparator, with some extras thrown in for convenience. Product is in design stage Target: Triangle wave oscillator So a natural question to ask is: Output drivers The UC output is itself a totem-pole:

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