TLE9877QXA20_15 Datasheet, PDF (76/122 Pages) Infineon Technologies AG – Microcontroller with LIN and BLDC MOSFET Driver for Automotive Applications

27
Current Sense Amplifier
TLE9877QXA20
Current Sense Amplifier
27.1
Features
Main Features
• Programmable gain settings: G = 10, 20, 40, 60
• Differential input voltage: ± 1.5V / G
• Wide common mode input range ± 2 V
• Low setting time < 1.4 µs
27.2
Introduction
The current sense amplifier in Figure 31 can be used to measure near ground differential voltages via the 10-bit
ADC. Its gain is digitally programmable through internal control registers.
Linear calibration has to be applied to achieve high gain accuracy, e.g. end-of-line calibration including the shunt
resistor.
Figure 31 shows how the current sense amplifier can be used as a low-side current sense amplifier where the
motor current is converted to a voltage by means of a shunt resistor R_SH. A differential amplifier input is used in
order to eliminate measurement errors due to voltage drop across the stray resistance R_Stray and differences
between the external and internal ground. If the voltage at one or both inputs is out of the operating range, the
input circuit is overloaded and requires a certain specified recovery time.
In general, the external low pass filter should provide suppression of EMI.
27.2.1 Block Diagram
VBAT
M
VZ E RO
Motor
Current
VP
RSH
VN
RStray
Ext. GND
LP Filter
ROPAFILT
COPAFILT
ROPAFILT
OP2
Amplifier
configurable
Gain: 10, 20, 40, 60
Vzero + (VOP2 -VOP1) * G
OP1
CSA_CTRL
Figure 31 Simplified Application Diagram
Data Sheet
76
VAREF
5V
10-bit ADC
10
/
ADC1_OUT_CH1
Current_Sense_Amplifier .vsd
Rev. 1.0, 2015-04-30