DRV3204-Q1_15 Datasheet, PDF (22/38 Pages) Texas Instruments – Three-Phase Brushless Motor Driver

DRV3204-Q1
SLVSBT3B – MARCH 2013 – REVISED JULY 2013
www.ti.com
Motor-Current Sense
Description:
Operational amplifier is operating with an external resistor network for higher flexibility to adjust the current
measurement to application requirements. The first-stage amplifier is operating with the external resistor and the
output voltage up to VB at ALFB. The gain of amplifier is adjustable by external resistors from ×10 to ×30. The
second-stage amplifier is buffer to MCU at ALV. Current sense has comparator for motor overcurrent (OVAD).
ADTH is overcurrent threshold level and set value by SPI. Figure 15 shows the curve of detection level. ALFB is
divided by 2 and compare this value with ADTH. In recommended application, zero-point adjustment is required
as large error offset in initial condition.
OVAD
VCC
+
-
1/2ALFB
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: 0.5/1.0/1.5/2.0/2.5 V (SPI)
*ADTH: 2.0/2.5/3.0/3.5/4.0 V (SPI)
*ALV = VGain * (Rshunt * Imotor) + AREF
*OVADth = (2 * ADTH - AREF) / (Rshunt * VGain)
Figure 15. Motor Current-Sense Block Diagram
22
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