DRV3202-Q1 Datasheet, PDF (25/41 Pages) Texas Instruments – DRV3202-Q1 3-Phase Brushless Motor Driver

Not Recommended for New Designs
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DRV3202-Q1
SLVSBJ4B – OCTOBER 2012 – REVISED JULY 2016
Feature Description (continued)
7.2.7 Motor Current Sense
The 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 the amplifier is adjustable by external resistors from x10 to x30.
The second stage amplifier is a buffer to MCU at ALV. Current sense has a comparator for motor overcurrent
(OVAD). ADTH is the overcurrent threshold level and sets the value by the external resistor as well. Figure 9
shows the curve of the detection level. ALFB is divided by 2, compare this value with ADTH. In the
recommended application, zero-point adjustment is required as a large error offset in the initial condition.
OVAD
V_CC
+-
R3
½ ALFB
ADTH
CLAMP
CLAMP
R4
V_CC
+
-
ALV
VB
-
+
ALFB
R22
ALP
ALM
C1
Battery
R11
R_shunt
I_motor
*R11, R12, R21, R22 # 0.1%
*V_Gain
X10: R11 = R12 = 3 k , R21 = R22 = 30 k _{1 V}
X20: R11 = R12 = 1.5 k , R21 = R22 = 30 k
X30: R11 = R12 = 1 k , R21 = R22 = 30 k
C2 = 10 n ~ 20 nF
C1 = 0 ~ 10 pF
*ALV = V_Gain x (R_shunt x l_motor) + AREF
*ADTH = {R4 / (R3 + R4)} x V_CC
*OVAD = (2 x ADTH ± AREF) / (R_shunt x V_Gain)
V_CC
+
-
AREF
R21
CLAMP
Figure 20. Motor Current Sense Block Diagram
R12
M
C2
7.2.8 Phase Amplifier (Sample and Hold Mode and Through Mode)
The 3-channel amplifier module monitors the drain-source for high-side and low-side FETs. Two modes (selected
by the SPI) are provided: sample and hold mode, and through mode. Sample and hold is controlled by PSSx at
the external pins and PSCx connects the charging capacitor. Through mode is real-time detection and the
amplifier has x1–x4 gain control.
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