Tronium Primary-Side Remote Sensing Brief
Semitrex’s TRONIUM™ Primary-Side Remote Sensing (PSRS™) semiconductor architecture
reduces parts necessary on a power supply, while keeping tight regulation for all types of
power topologies from forward convertors to flyback configurations.
The TRONIUM PSRS relies on the principle of sensing the instantaneous current and
voltage seen by the primary winding of the transformer before a full collapse and reset.
This information can then be used to accurately regulate the secondary output voltage by
Pulse-Width-Modulation (PWM) of the primary-side MOSFET switch providing highly
efficient sensing at low, medium and high current demands.
The primary benefit of this architecture is the elimination of feedback from the secondary
side of the transformer which must cross the isolation boundary with an opto-isolator. As a
result, a reduction in typically 9 components and their associated cost is obtained. An
added benefit is the greatly improved efficiency of the power supply at light and medium
loads, with regulation deviance within 1%.
The TRONIUM PSRS chip’s embedded servo loops reduce the duty cycle at light loads in
order to maintain tight regulation which results in better efficiency as compared to the
opto-isolator based sensor and other primary regulation topologies.
Instead of needing a tertiary (third), like competitor’s primary regulation techniques,
Semitrex’s uses information obtained from the existing secondary transformer. In a
revolutionary development, the Semitrex solution relies on an equation, embedded into the
chip, which accounts for full depletion of the secondary winding energy, as well as losses
from the secondary side parts IR drops.
This ultra-efficient parts reducing technology promises to add manufacturing simplicity at
a lower cost. A comparison of this architecture to other methods is shown in
5-Mar-15
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Table 1: Comparison of TRONIUM Primary-Side Regulation to Other Methods
Parameter
TRONIUM PSR
Primary-Side Remote
Sensing
PSR - Competition
Opto-Isolator Based
Secondary Sensor
Architecture
Forward Convertor
Fly Back / Forward
Fly Back/Forward
Power Efficiency
at light loads
Very High Efficiency
Lower Efficiency due to
need for third winding,
sensors and micro
Lower Efficiency due to 9
additional parts needed
As simulated by Semitrex,
is a drag on efficiency,
however, not evaluated by
competition data sheets
Current needed by the
secondary side opamp +
resistor divider + opto
isolator creates much
higher energy draw on
power system
No external parts needed
Tertiary winding and
microcontroller required
7-9 external components
needed including optoisolator – high cost parts
Voltage
Regulation
Within 1%
Having tertiary winding will
decreases accuracy due
to imperfect coupling of
the tertiary to primary
windings
<5%, typical - unlimited
resolution since it is
analog depending on how
much is spent for parts
Die Size
No significant impact
N/A
9 additional parts needed
to perform isolated
secondary sensing
IR drop
compensation
For higher
accuracy
IR drop compensation
loop Included
Competition does not
calculate losses, thus,
regulation is out of sync
with current demand
Not an issue, since the
output voltage is being
directly sensed but cost is
increased by 9 parts
Light Load
Compensation
Included
Not used by competition
Not applicable
Overhead
Current
External Parts
5-Mar-15
Minimal current needed by
resistor divider, counter
Overall no maintains very
high energy efficiency
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Power Semiconductor Solutions - © Semitrex, LLC 2015 all rights reserved