mm908e626 Freescale Semiconductor, Inc, mm908e626 Datasheet - Page 24

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

HALF-BRIDGE CURRENT LIMITATION
current feature. This features is realized by a pulse width
modulation on the low-side MOSFET. The pulse width
modulation on the outputs is controlled by the FGEN input
and the load characteristics. The FGEN input provides the
PWM frequency, whereas the duty cycle is controlled by the
load characteristics.
Offset Chopping
set, HB1 and HB2 will continue to switch on the low-side
24
908E626
FUNCTIONAL DEVICE OPERATION
LOGIC COMMANDS AND REGISTERS
Low-Side Output
• 0 = High-side MOSFET turned on for half-bridge output
Each low-side MOSFET offers a current limit or constant
If bit OFC_EN in the H-Bridge Control Register (HBCTL) is
Coil Current
(MCU PWM
FGEN Input
Half-Bridge
Signal)
x.
Minimum 50 µs
Figure 12. Half-Bridge Current Limitation
PWM is 0.1 kHz to 20 kHz.
Functionality
selected current limit was detected. The 908E626 offers five
different current limits (refer to
limit values). The low-side MOSFET switches on again if a
rising edge on the FGEN input was detected
MOSFETs with the rising edge of the FGEN signal and HB3
and HB4 will switch on the low-side MOSFETs with the falling
edge on the FGEN input. In step motor applications, this
The recommended frequency range for the FGEN and the
Each low-side MOSFET switches off if a current above the
Analog Integrated Circuit Device Data
Table
H-Bridge low-side
MOSFET will be switched
off if select current limit is
reached.
H-Bridge low-side
MOSFET will be turned on
with each rising edge of
the FGEN input.
Freescale Semiconductor
5, page 27, for current
(Figure
t (µs)
t (µs)
t (µs)
12).