33926 Datasheet, PDF (12/24 Pages) Freescale Semiconductor, Inc – 5.0 A Throttle Control H-Bridge

FUNCTIONAL DESCRIPTION
FUNCTIONAL PIN DESCRIPTION
H-BRIDGE OUTPUT (OUT1, OUT2)
These pins are the outputs of the H-Bridge with integrated
free-wheeling diodes. The bridge output is controlled using
the IN1, IN2, D1, and D2 inputs. The outputs have PWM
current limiting above the I_LIM threshold. The outputs also
have thermal shutdown (tri-state latch-OFF) with hysteresis
as well as short circuit latch-OFF protection.
A disable timer (time t _b) is incorporated to distinguish
between load currents that are higher than the I_LIM threshold
and short circuit currents. This timer is activated at each
output transition.
CHARGE PUMP CAPACITOR (CCP)
This pin is the charge pump output pin and connection for
the external charge pump reservoir capacitor. The allowable
value is from 30 nF to 100 nF. This capacitor must be
connected from the CCP pin to the VPWR pin. The device
cannot operate properly without the external reservoir
capacitor.
ENABLE INPUT (EN)
The EN pin is used to place the device in a Sleep mode so
as to consume very low currents. When the EN pin voltage is
a logic LOW state, the device is in the Sleep mode. The
device is enabled and fully operational when the EN pin
voltage is logic HIGH. An internal pulldown resistor maintains
the device in Sleep mode in the event EN is driven through a
high impedance I/O or an unpowered microcontroller, or the
EN input becomes disconnected.
FEEDBACK (FB)
The 33926 has a feedback output (FB) for “real time”
monitoring of H-Bridge high-side output currents to facilitate
closed-loop operation for motor speed and torque control.
The FB pin provides current sensing feedback of the
H-Bridge high-side drivers. When running in the forward or
reverse direction, a ground-referenced 0.24% of load current
is output to this pin. Through the use of an external resistor to
ground, the proportional feedback current can be converted
to a proportional voltage equivalent and the controlling
microcontroller can “read” the current proportional voltage
with its analog-to-digital converter (ADC). This is intended to
provide the user with only first-order motor current feedback
for motor torque control. The resistance range for the linear
operation of the FB pin is 100 < R_FB < 300 W.
If PWM-ing is implemented using the disable pin inputs
(either D1 or D2), a small filter capacitor (~1.0 µF) may be
required in parallel with the R_FB resistor to ground for spike
suppression.
33926
12
Analog Integrated Circuit Device Data
Freescale Semiconductor