TMC2100 DATASHEET (Rev. 1.07 / 2017-MAY-15)
12
RREF
DAC Reference
IREF
OA1
N
Full Bridge A
stepper
motor
OA2
S
BRA
Driver
OB1
OB2
Full Bridge B
BRB
Figure 4.2 RDSon based sensing eliminates high current sense resistors
4.4 External 5V Power Supply
When an external 5V power supply is available, the power dissipation caused by the internal linear
regulator can be eliminated. This especially is beneficial in high voltage applications, and when
thermal conditions are critical. There are two options for using an external 5V source: either the
external 5V source is used to support the digital supply of the driver by supplying the VCC pin, or the
complete internal voltage regulator becomes bridged and is replaced by the external supply voltage.
4.4.1 Support for the VCC Supply
This scheme uses an external supply for all digital circuitry within the driver (Figure 4.3). As the digital
circuitry makes up for most of the power dissipation, this way the internal 5V regulator sees only low
remaining load. The precisely regulated voltage of the internal regulator is still used as the reference
for the motor current regulation as well as for supplying internal analog circuitry.
When cutting VCC from 5VOUT, make sure that the VCC supply comes up before or synchronously
with the 5VOUT supply to ensure a correct power up reset of the internal logic. A simple schematic
uses two diodes forming an OR of the internal and the external power supplies for VCC. In order to
prevent the chip from drawing part of the power from its internal regulator, a low drop 1A Schottky
diode is used for the external 5V supply path, while a silicon diode is used for the 5VOUT path.
+VM
VSA
5V Voltage
regulator
5VOUT
100n
4.7µ
LL4448
+5V
VCC
MSS1P3
470n
VCC supplied from external 5V. 5V or 3.3V IO voltage.
Figure 4.3 Using an external 5V supply for digital circuitry of driver
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