TMC603 DATA SHEET (V. 1.06 / 26. Mar. 2009)
17
+VM
HS1
Z 12V
BM1
Motor
220R
LS1
GNDP
figure 11: parallel Schottky diode avoids current spikes due to bulk diode recovery
5.2.9 Short to GND detection
An overload condition of the high side MOSFET (“short to GND”) is detected by the TMC603, by
monitoring the BM voltage during high side on time. Under normal conditions, the high side power
MOSFET reaches the bridge supply voltage minus a small voltage drop during on time. If the bridge is
overloaded, the voltage cannot rise to the detection level within a limited time, defined by an external
resistor. Upon detection of an error, the error output is activated. By directly tying it to the enable input,
the chip becomes disabled upon detection of a short condition and the error flip flop becomes set.
A variation of the short to GND detection delay allows adaptation to the slope control, and modification
of the sensitivity of the detection during power up.
BHx
BMx
0V
VVM
VVM
-
Short to GND
detected
Valid area
VBMS2G
Short
detection
0V
Driver off via
ENABLE pin
/ERROUT,
ENABLE
0V
tS2G
tS2G
Short to GND
monitor phase
BMx voltage
monitored
inactive delay
inactive
delay
Short detected
figure 12: timing of the short to GND detector
Pin
Comments
RS2G
The resistor connected to this pin controls the delay between switching on the high
side MOSFET and the short to GND check. A 20 µA current out of this pin (resistor
value of 220 k to GND) results in a 500 ns delay, a lower current gives a longer
delay. Disconnecting the pin disables the function. Keep interconnection between IC
and resistor short, to avoid stray capacitance to adjacent signal traces of modulating
the set current.
Resistor range: 47 k to 1 M
5.2.10 Error logic
The TMC603 has three different sources for signaling an error:
Undervoltage of the low side supply
Undervoltage of the charge pump
Short to GND detector
Upon any of these events the error output is pulled low. After a short to GND detector event, the error
output remains active, until it becomes cleared by the CLR_ERR. By tying the error output to the
enable input, the TMC603 automatically switches off the bridges upon an error. The enable input then
should be driven via an open collector input plus pull-up resistor, or via a resistor.
Copyright © 2008 TRINAMIC Motion Control GmbH & Co. KG
TRINAMIC [ TRINAMIC MOTION CONTROL GMBH & CO. KG. ]
