mm908e626 Freescale Semiconductor, Inc, mm908e626 Datasheet - Page 25

• Manufacturer Part Number: mm908e626
• Description: Integrated Stepper Motor Driver With Embedded Mcu And Lin Serial Communication
• Manufacturer: Freescale Semiconductor, Inc

feature allows the reduction of EMI due to a reduction of the
di/dt
HALF-BRIDGE CURRENT RECOPY
allow a current recopy feature. This sense source is internally
connected to a shunt resistor. The drop voltage is amplified
and switched to the analog multiplexer.
selected via bit CSA in the System Control Register.
Analog Integrated Circuit Device Data
Freescale Semiconductor
Coil1 Current
Coil2 Current
(MCU PWM
FGEN Input
VSUP Line
Current in
Each low-side MOSFET has an additional sense output to
The factor for the current sense amplification can be
• CSA = 1: Low resolution selected (500 mA
• CSA = 0: High resolution selected (2.5 A measurement
Signal)
(Figure
measurement range).
range).
).
Figure 13. Offset Chopping for Step Motor Control
HALF-BRIDGE BEMF GENERATION
detected in any half-bridge. This recirculation current flows
via the two freewheeling diodes of the power MOSFETs. The
BEMF circuitry detects that and generates a HIGH on the
BEMF output as long as a recirculation current is detected.
This signal provides a flexible and reliable detection of stall in
step motor applications. For this the BEMF circuitry takes
advantage of the instability of the electrical and mechanical
behavior of a step motor when blocked. In addition the signal
can be used for open load detection (absence of this signal)
(see
The BEMF output is set to “1” if a recirculation current is
Figure
14, page 26).
LOGIC COMMANDS AND REGISTERS
FUNCTIONAL DEVICE OPERATION
HB1
HB2
HB3
HB4
Coil2…..
Coil1…..
908E626
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