MAX14871_14 Datasheet, PDF (10/15 Pages) Maxim Integrated Products – 4.5V to 36V Full-Bridge DC Motor Driver

MAX14871
4.5V to 36V Full-Bridge DC Motor Driver
Functional Diagram
EN
PWM
DIR
FAULT
VDD
DRIVER
M1
M2
VDD
VDD
MAX14871
DRIVER
MODE
VREF
TCOFF
CURRENT
REGULATION
SNS
COM
GND
RSENSE
Detailed Description
The MAX14871 DC brushed motor driver provides a
low-power and flexible solution for driving and controlling
brushed motors with voltages between 4.5V and 36V.
Peak motor currents of up to 2.8A ensure for large motor
torque that is controllable by an external PWM signal and/
or by autonomous internal current regulation.
Charge-pump-less design ensures for minimal external
components and low supply current.
Integrated current regulation allows limiting peak startup
motor currents. Shoot-through protection with a 140ns
(typ) dead time ensures low operating current. Internal
free-wheeling diodes absorb inductive motor currents. The
FAULT output signals thermal overload and overcurrents.
Overcurrent Protection
The MAX14871 is protected against shorts on M1/M2 to
any voltages between VDD and GND, including shorts
to GND, VDD and between M1 and M2 via overcurrent
limiting. When a current above 6A (typ) flows through
M1 or M2 for longer than 1µs, an overcurrent condition
is detected and the H-bridge drivers are automatically
disabled and the FAULT output asserts.
If the overcurrent condition continues for longer than the
overcurrent autoretry timeout (2ms (typ)) the MAX14871
enters autoretry mode. In autoretry mode, the M1 and M2
outputs are re-enabled for 1µs (typ) and FAULT goes high
impedance. The drivers are disabled again and FAULT is
re-asserted if the overcurrent condition persists.
PWM Control
The PWM input is used for motor speed/torque control.
Increasing or decreasing the duty cycle at PWM sets the
effective (average) voltage across the motor terminals
and allows first-order speed control.
When PWM is logic-high, the motor is driven in the
direction defined by DIR. When PWM is logic low, the
bridge is in brake mode. In brake mode, the motor current
continues flowing and recirculates through the low-side
transistors of the H-bridge driver, due to its inductive
impedance and back EMF.
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