908E425 Datasheet, PDF (31/49 Pages) Freescale Semiconductor, Inc – Integrated Quad Half H-Bridge with Power Supply, Embedded MCU, and LIN Serial Communication

• 0 = Low-side MOSFET turned off for half-bridge
output x
HIGH-SIDE ON/OFF BITS (HBX_H )
These read / write bits turn on the high-side MOSFETs.
Reset clears the HBx_H bits.
• 1 = High-side MOSFET turned on for half-bridge
output x
• 0 = High-side MOSFET turned on for half-bridge
output x
HALF-BRIDGE CURRENT LIMITATION
Each low-side MOSFET offers a current limit or constant
current feature. This features is realized by a pulse width
modulation on the low-side MOSFET. The pulse width
Coil Current
Half-Bridge
Low-Side Output
FUNCTIONAL DEVICE OPERATION
LOGIC COMMANDS AND REGISTERS
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.
The recommended frequency range for the FGEN and the
PWM is 0.1 kHz to 20 kHz.
FUNCTIONALITY
Each low-side MOSFET switches off if a current above the
selected current limit was detected. The 908E425 offers five
different current limits. Refer to Table 10 for current limit
values. The low-side MOSFET switches on again if a rising
edge on the FGEN input was detected (Figure 18).
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.
t
FGEN Input
(MCU PWM
Signal)
Minimum 50 µs
Figure 18. Half-Bridge Current Limitation
Analog Integrated Circuit Device Data
Freescale Semiconductor
t
t
908E425
31