TLE7188F Datasheet, PDF (21/28 Pages) Infineon Technologies AG – 3-Phase Bridge Driver IC

TLE7188F
Shunt Signal Conditioning
5.3
Shunt Signal Conditioning
The TLE7188F 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 kOhm,
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 5 to 15.
When V(ISP) = V(ISN), VO provides the reference voltage VRO. 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 TLE7188F demonstrate low offset
voltages and very little drift over temperature, thus allowing accurate phase current measurements.
TLE7188F
to Error
logic
Over _blanking
current _time
1.5µs
OC
Comp
Over
current
blanking
time
1.5µs
OC
Comp
+ _Bias
Reference
-
I-DC Link
OpAmp1
I-DC Link
OpAmp2
5V
Adjustable
R_VRI
bias
VRI
reference
VRO
R_VRI
C_VRI
Rfb
Rfb
ISP1
Rfb
Rs
Rs
ISN1
Rfb
Rs
ISP2
Rs
ISN2
Shunt 1
V_IN1
Shunt 2
Over
current
blanking
time
1.5µs
OC
Comp
I-DC Link
OpAmp3
ISP3
ISN3
VTHOC VO3 VO2
VO1
Rs
Shunt 3
Rs
5V
Figure 4
R_VRI < 50 kOhm
C_VRI < 1.2 µF (if needed)
to ADCs
Adjustable over current limit
(VTHOC = 0 OC disabled)
Shunt Signal Conditioning Block Diagram and Over Current Limitation
Over current warning see Chapter 5.2.2.
Data Sheet
21
V2.1, 2007-06-20