PIIPM50P12B004X Vishay, PIIPM50P12B004X Datasheet - Page 14

• Manufacturer Part Number: PIIPM50P12B004X
• Description: IC PWR MODULE PROG ISO 50A 1200V
• Manufacturer: Vishay

Specifications of PIIPM50P12B004X

• Module/board Type: Programmer Module
• For Use With/related Products: Servo Motors
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

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PIIPM50P12B004
acts as a buffer of the partition at 3.30V created
down the 5V reference. This 3.30V is used also
as reference for the DSP A/D converter. It has to
be noted that in the schematic we are using the
same linear regulator as a starting point for all
reference voltages. In fact if the 5V linear
regulator drifts in temperature or time, then all
references (even the 3.30V being this a simple
partitioning) follow in track and still keep the
overall chain precision. The trimming is then
done only once, in a single point of the
measuring chain, that is the conditioning op-amp
collecting the current sensing ICs signal as will
then be described in the following chapter.
3. Current sensing interfaces, over-current
protections and signal conditioning.
This block is the real critical point of the system.
Current measuring performances directly impact
on motor control performances in a servo
application: errors in current evaluation, delay in
its measuring chain or poor overall precision of
the system, such as scarce references or lower
number of significant A/D bits, inevitably results
in unwanted trembling and unnatural noise
coming from the motor while running at lower
speed or at blocked shaft conditions.
In the PI-IPM50P12B004 the current sensing
function is done through three sensing resistors
dropout measurement, one on each output phase,
with the benefit of a lower area and somewhat a
lower cost compared to the well-known Hall
effect devices. This solution has the added value
of having the shunts element embedded in the
power module with all Kelvin connections
available, avoiding any noise due to long routing
of power paths.
As the block schematic on page 2 shows, the
voltage across each sensing resistor is applied,
through an anti-aliasing 400kHz filter, at the
input of a current sense IC and then to a signal
conditioning circuit.
Though the block schematic here shows an Op-
Amp plus an external passive filter this is simply
realized implementing a VCVS cell (i.e. a
Constant Gain or Sallen – Key cell) configured
I27146
06 - Oct
so that the offset and gain is easily trimmed by
three on board resistors. The filter implemented
is a second order Bessel with 5.5kHz pole
frequency, the reason for this is that this type of
polynomials are calculated with the aim of
having a constant group delay within the pass-
band frequencies, thus giving the minimum
waveform distortion to the output signal up to
almost twice the filter pole. In other words we
could also say that the group delay of the signal
chain from the sensing resistor up to the ADC
input of the DSP is constant from 0 to 5.5kHz.
Signal outputted from the overall chain has a 0 to
+3.30V dynamic, with a sensing resistor of
2mohms the input measured current range is +/-
100A then we have a situation as follows:
Summing
performances are shown in the following table:
The
consequently the PI-IPM50P12B004 has a
minimum
approximately:
that is:
The over current protection is provided also
through the current sensing ICs, the related fault
signal is activated when a 250mV voltage across
current range
Gain and Offset
precision
Bandwidth
latency time
“2406A”
PI-IPM Current sensing chain typical
LSB
up
appreciable
. 0
1
100
LSB 195
100
00
performances
DSP
our
2
*
2
A
100
10
A
A
current
. 1
has
0
. 3
65
Value
0 .
+/- 100
+/- 1.8
30
current
. 0
mA
V
V
5.5
10
1953
V
a
measurements
10bit
step
kHz
Units
%
A
ADC,
s
14
of