TMC603A Datasheet, PDF (13/44 Pages) TRINAMIC Motion Control GmbH & Co. KG. – Three phase motor driver with BLDC back EMF commutation hallFX™ and current sensing

TMC603A DATA SHEET (V. 1.15 / 2009-Nov-19)
13
PWM1
Microcontroller
with BLDC PWM
unit
OUT1
PWM1
OUT2
BH1
BL1
PWM1
OUT
BH1
Microcontroller with
3 PWM outputs
BL1
INV_BL
+VCC
BBM_EN
PWM1
Microcontroller
with 3 PWM
outputs
OUT
DIG
OUT
BH1
BL1
Microcontroller with
3 PWM outputs
PWM1
OUT
DIG OUT /
HI-Z
BH1
2k2 _BL1
INV_BL
+VCC
BBM_EN
TMC603
TMC603
TMC603
TMC603
Block (Hall or hallFX) or
sine commutated BLDC
motor
Sine commutated BLDC
motor
Block (Hall) commutated
BLDC motor
Block (Hall) or sine
commutated BLDC
motor
DIG OUT
BH1
Microcontroller
with 1 PWM output
DIG OUT
BL1
PWM1
OUT
ENABLE
2k2
DIG IN /ERR_OUT
+VCC
BBM_EN
TMC603
Block (hallFX)
commutated BLDC
motor
figure 7: examples for microcontroller PWM control
5.2.4 Slope control
The TMC603 driver stage provides a constant current output stage slope control. This allows to adapt
driver strength to the drive requirements of the power MOSFET and to adjust the output slope by
providing for a controlled gate charge and discharge. A slower slope causes less electromagnetic
emission, but at the same time power dissipation of the power transistors rises. The duration of the
complete switching event depends on the total gate charge. The voltage transition of the output takes
place during the so called miller plateau (see figure 6). The miller plateau results from the gate to drain
capacity of the MOSFET charging / discharging during the switching. From the datasheet of the
transistor (see example in figure 8) it can be seen, that the miller plateau typically covers only a part
(e.g. one quarter) of the complete charging event. The gate voltage level, where the miller plateau
starts, depends on the gate threshold voltage of the transistor and on the actual load current.
MOSFET gate charge vs. switching event
10
25
V_M
8
20
6
15
4
10
2
5
0
0
0
5
10
15
20
25
QMILLER
Q_G – Total gate charge (nC)
figure 8: MOSFET gate charge as available in device data sheet vs. switching event
Copyright © 2009 TRINAMIC Motion Control GmbH & Co. KG