DRV3202-Q1_15 Datasheet, PDF (22/39 Pages) Texas Instruments – 3-Phase Brushless Motor Driver

DRV3202-Q1
SLVSBJ4A – OCTOBER 2012 – REVISED DECEMBER 2012
MOTOR CURRENT SENSE
www.ti.com
Description
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 18
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 17. Motor Current Sense Block Diagram
R12
M
C2
MOTOR CURRENT SENSE ELECTRICAL CHARACTERISTICS⁽¹⁾
VB = 12 V, T_A = –40°C to 125°C (unless otherwise specified)
PARAMETER
MOTOR CURRENT⁽²⁾ SENSE
CONDITIONS
V_Ofs
V_{O_0}
Input offset voltage
Output voltage (ALV)
VB = 5.3 ~ 18 V,
I_motor = 0 A
(1) No variation of the external components
(2) Motor current is converted to voltage in test
22
Submit Documentation Feedback
Product Folder Links: DRV3202-Q1
MIN TYP MAX UNITS
–5
1
5 mV
V
Copyright © 2012, Texas Instruments Incorporated