TLE7189F Datasheet, PDF (22/29 Pages) Infineon Technologies AG – 3-Phase Bridge Driver IC

TLE7189F
5.3
Shunt Signal Conditioning
The TLE7189F incorporates three fast and precise operational amplifiers for conditioning and amplification of the
shunt signals sensed in the three phases. Additionally, one reference bias buffer is integrated to provide an
adjustable bias reference for the three OpAmps. The voltage divider on the VRI pin should be less than 50 kΩ, the
filtering capacitor less than 1.2 µF - if needed at all. The gain of the OpAmps is adjustable by external resistors
within a range of 3 to 20 or more, as long as the band width satisfies the need of the application.
In the circuit example below VO1 provides the reference voltage V_VRO, when the shunt voltage is zero. V_VRO is
normally half of the regulated voltage provided from an external voltage regulator for the ADC used to read the
current sense signal. The additional buffer allows bi-directional current sensing and permits the adaptation of the
reference bias to different µC I/O voltages. The reference buffer assures a stable reference voltage even in the
high frequency range.
The reference bias buffer is used for all of the OpAmps. The OpAmps of the TLE7189F demonstrate low offset
voltages and very little drift over temperature, thus allowing accurate phase current measurements.
C_VRI < 1.2 µF (if needed)
R_VRI < 50 kOhm
TLE7189
Dependent on
customer specific
requirements additional
filtering can be
necessary
+ _{Bi as}
Reference
-
I-DC Link
OpAmp1
I-DC Link
OpAmp2
I-DC Link
OpAmp3
3.3V
Adjustable
R_VRI
bias
VRI
reference
VRO
R_VRI
C_VRI
Rfb
Rfb
ISP1
Rfb
Rs
Rs
ISN1
Rfb
Rs
ISP2
Rs
ISN2
Shunt
Rs
ISP3
Rs
ISN3
VO3 VO2
VO1
1k
1k
Figure 4
to ADCs
Shunt Signal Conditioning Block Diagram
Data Sheet
22
Rev. 2.1, 2007-05-30