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#1 Jun 12, 2017
Mirko
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Last seen: 6 years 8 months ago
Joined: 2016-07-19 07:39

Pspice SAC models doc

I would like to try using state space average models of corrent mode controllers (like UC2842- uc184x family) for transient and possibly ac analysis. They are available by placing Pspice component/search/power management/state average controllers/pwm controller.

However I can't find documentation or schematic examples on how to connect and use such models, since they have extra-pins compared with same traditional switching model counterparts.

Any suggestion?

 

Regards

 

Fri, 2017-06-16 09:59
oldmouldy
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Joined: 2016-07-06 04:23

Try a Search of the help for "state average" with the PSpice entry selected in the product tree of the Cadence Help application, there is a document named PSpice Library Models Data Book which should help, chapter 1 is Power Management Controller ICs.

Tue, 2017-07-04 05:49
Mirko
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Thank you oldmouldy. The only match in Cadence help for "state average" I am able to find is the "dc transformer" in the pspice reference guide.

I found the PSpice Library Models Data Book  document, however state average is not mentioned...

Tue, 2017-07-04 12:53
alok
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Joined: 2016-05-10 23:49

Here some generic details about SAC models available with PSpice

The state-average model calculates duty cycle internally and represents it as a voltage between 0 and 1V. The fractional ON time of the power supply switch is directly
proportional to the DC output voltage of the state-average controller. The model allows small-signal measurement of the PWM transfer function for frequency domain analysis.
Switching delay, rise and fall time specifications do not apply to these models. 

DEAD_TIME (measured in seconds) is the power supply’s minimum off time during a switching cycle. This parameter sets the maximum duty cycle of the state average
controller.
MAX_V (measured in volts) is the peak voltage of the sawtooth waveform at the comparator input.
MIN_V (measured in volts) is the minimum value of the sawtooth waveform at the comparator input.
PERIOD (measured in seconds) is the inverse of the oscillator switching frequency.

Although there is no switching waveform in a state average model, the PERIOD provides a scaling factor to set the minimum and maximum duty cycle along with
DEAD_TIME and SWITCHTIME.
SWITCHTIME (measured in seconds) is the switching transistor storage time, plus any turnoff delays associated with the base/gate drive circuit.

GM (measured in siemens) is the DC transconductance of the amplifier.
It relates to DC open-loop voltage gain (Av) according to the following equation: AV = GM*RL, where RL is the resistance from pin 9 to ground.
AVMAX (measured in 1) is the maximum open-loop voltage gain

A voltage-mode state average controller has access to the average value of current, but cannot model peak current limiting functions.

The error amplifier section is modeled with a single dominant pole. CMRR and PSRR are not modeled.

Hope this helps. 

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