Freescale Semiconductor, Inc.
SYSTEM/APPLICATION INFORMATION
INTRODUCTION
Numerous protection and operational features (speed,
torque, direction, dynamic braking, and PWM control), in
addition to the 5.0 A current capability, make the 33886 a very
attractive, cost-effective solution for controlling a broad range of
fractional horsepower DC motors. A pair of 33886 devices can
be used to control bipolar stepper motors in both directions. In
addition, the 33886 can be used to control permanent magnet
solenoids in a push-pull variable force fashion using PWM
control. The 33886 can also be used to excite transformer
primary windings with a switched square wave to produce
secondary winding AC currents.
Two independent inputs (IN1 and IN2) provide control of the
two totem-pole half-bridge outputs. Two disable inputs (D1 and
D2) are for forcing the H-Bridge outputs to a high impedance
state (all H-Bridge switches OFF).
The 33886 has undervoltage shutdown with automatic
recovery, active current limiting, output short-circuit latch-OFF,
and overtemperature latch-OFF. An undervoltage shutdown,
output short circuit latch-OFF, or overtemperature latch-OFF
fault condition will cause the outputs to turn OFF (i.e., become
high impedance or tri-stated) and the fault output flag to be set
Low. Either of the Disable inputs or V+ must be 鈥渢oggled鈥?to
clear the fault flag.
The short circuit/overtemperature shutdown scheme is
unique and best described as using a junction temperature-
dependent active current 鈥渇old back鈥?protection scheme. When
a short circuit condition is experienced, the current limited
output is 鈥渞amped down鈥?as the junction temperature increases
above 160擄C, until at 175擄C the current has decreased to about
2.5 A. Above 175擄C, overtemperature shutdown (latch-OFF)
occurs. This feature allows the device to remain in operation for
a longer time with unexpected loads, while still retaining
adequate protection for both the device and the load.
Freescale Semiconductor, Inc...
As shown in
Figure 1,
Simplified Internal Block Diagram,
page 2, the 33886 is a fully protected monolithic H-Bridge with
Fault Status reporting. For a DC motor to run the input
conditions need be as follows: D1 input logic Low, D2 input logic
High, FS flag cleared (logic High), with one IN logic Low and the
other IN logic High to define output polarity. The 33886 can
execute dynamic braking by simultaneously turning on either
both high-side MOSFETs or both low-side MOSFETs in the
output H-Bridge; e.g., IN1 and IN2 logic High or IN1 and IN2
logic Low.
The 33886 outputs are capable of providing a continuous DC
load current of 5.0 A from a 40 V V+ source. An internal charge
pump supports PWM frequencies up to 10 kHz. An external
pull-up resistor is required for the open drain FS terminal for
fault status reporting.
FUNCTIONAL TERMINAL DESCRIPTION
PGND and AGND
Power and analog ground terminals. The power and analog
ground terminals should be connected together with a very low
impedance connection.
Fault Status (FS)
This terminal is the device fault status output. This output is
an active Low open drain structure requiring a pull-up resistor to
5.0 V. Refer to
Table 1, Truth Table,
page 14.
V+
V+ terminals are the power supply inputs to the device. All V+
terminals must be connected together on the printed circuit
board with as short as possible traces offering as low
impedance as possible between terminals.
V+ terminals have an undervoltage threshold. If the supply
voltage drops below a V+ undervoltage threshold, the output
power stage switches to a tri-state condition and the fault status
flag is set and the Fault Status terminal voltage switched to a
logic Low. When the supply voltage returns to a level that is
above the threshold, the power stage automatically resumes
normal operation according to the established condition of the
input terminals and the fault status flag is automatically reset
logic High.
IN1, IN2, D1, and D2
These terminals are input control terminals used to control
the outputs. These terminals are 5.0 V CMOS-compatible
inputs with hysteresis. The IN1 and IN2 independently control
OUT1 and OUT2, respectively. D1 and D2 are complimentary
inputs used to tri-state disable the H-Bridge outputs.
When either D1 or D2 is set (D1 = logic High or D2 = logic
Low) in the disable state, outputs OUT1 and OUT2 are both tri-
state disabled; however, the rest of the device circuitry is fully
operational and the supply I
Q(standby)
current is reduced to a few
milliamperes. Refer to
Table 1, Truth Table,
and
STATIC
ELECTRICAL CHARACTERISTICS
table, page 5.
MOTOROLA ANALOG INTEGRATED CIRCUIT DEVICE DATA
For More Information On This Product,
Go to: www.freescale.com
33886
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