DRV3203E-Q1 Datasheet, PDF (23/39 Pages) Texas Instruments – Three-Phase Brushless Motor Driver

DRV3203E-Q1
www.ti.com
SLVSCE5A – NOVEMBER 2013 – REVISED JANUARY 2014
Motor-Current Sense
Description:
The operational amplifier operates with an external resistor network for higher flexibility to adjust the current
measurement to application requirements. The first-stage amplifier operates with the external resistor and the
output voltage up to VB at ALFB. External resistors adjust the amplifier gain by 10 to 30 times. The second-stage
amplifier is buffered to MCU at ALV. The current sense has a comparator for motor overcurrent (OVAD). ADTH
is the overcurrent threshold level and is the value set by SPI. Figure 15 shows the curve of detection level. ALFB
is divided by 2. Compare this value with ADTH. In recommended application, the zero-point adjustment is
required as large error offset in initial condition.
OVAD
VCC
+±
½ALFB
CLAMP
ADTH
CLAMP
VCC
+
±
ALV
VB
±
+
ALFB
R22
ALP
ALM
C1
R11
Battery
Rshunt
Imotor
VCC
R21
+
AREF
R12
M
±
DC
C2
CLAMP
*R11, R12, R21, R22 z 0.1%
*VGain
X10: R11 = R12 = 3 k , R21 = R22 = 30 k
X20: R11 = R12 = 1.5 k , R21 = R22 = 30 k
X30: R11 = R12 = 1 k , R21 = R22 = 30 k
*C1 = 0~10 pF
*C2 = 10 nF
*AREF: 0.5/1.0/1.5 (SPI)
*ADTH: 1.32/1.65/1.98/2.31/2.64 V (SPI)
*ALV = VGain × (Rshunt × Imotor) + AREF
*OVADth = (2 × ADTH ± AREF) / (Rshunt × VGain)
Figure 15. Motor Current-Sense Block Diagram
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