TMC603A Datasheet, PDF (10/44 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)
10
5.2 MOSFET Driver Stage
The TMC603 provides three half bridge
drivers, each capable of driving two MOSFET
transistors, one for the high-side and one for
the low-side. In order to provide a low on-
resistance, the MOSFET gate driving voltage
is about 10V to 12V.
The TMC603 bridge drivers provide a number
of unique features for simple operation,
explained in the following chapters:
An integrated automatic break-before-
make logic safely switches off one
transistor before its counterpart can be
switched on.
Slope controlled operation allows
adaptation of the driver strength to the
desired slope and to the chosen
transistors.
The drivers protect the bridge actively
against cross conduction (Q_GD protection)
The bridge is protected against a short to
GND
VLS VCP
TMC603
HS-DRV
LS-DRV
HS-DRV
LS-DRV
+VM
HS1
Z 12V
BM1
220R
LS1
GNDP
+VM
HS2
Z 12V
BM2
220R
LS2
HS-DRV
LS-DRV
+VM
HS3
Z 12V
BM3
220R
LS3
3 phase
BLDC
motor
figure 4: three phase BLDC driver
5.2.1 Principle of operation
The low side gate driver voltage is supplied by the VLS pins. The low side driver supplies 0V to the
MOSFET gate to close the MOSFET, and VLS to open it.
The TMC603 uses the following driver principle for driving of the high side (pat. fil.):
The high-side MOSFET gate voltage is referenced to its source at the center of the half bridge. Due to
this, the TMC603 references the gate drive to the bridge center (BM) and has to be able to drive it to a
voltage lying above the positive bridge power supply voltage VM. This is realized by a charge pump
voltage generated from the switching regulator via a Villard circuit. When closing the high-side
MOSFET, the high-side driver drives it down to the actual BM potential, since an external induction
current from the motor coil could force the output to stay at high potential. This is accomplished by a
feedback loop and transistor TG1 (see figure). In order to avoid floating of the output BM, a low current
is still fed into the HS output via transistor TG1a. The input BM helps the high side driver to track the
bridge voltage. Since input pins of the TMC603 must not go below -0.7V, the input BM needs to be
protected by an external resistor. The resistor limits the current into BM to a level, the ESD protection
input diodes can accept.
High side driver
HS On
HS Off
VCP
Ion
TG1
+VM
HS
Z 12V
BM
220R
LS
T1
one coil
of motor
TG1a
Ioff
Iholdoff
one NMOS
halfbridge
figure 5: principle of high-side driver (pat. fil.)
Copyright © 2009 TRINAMIC Motion Control GmbH & Co. KG