33932 datasheet(12/21 Pages) FREESCALE

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Analog Integrated Circuit Device Data

Freescale Semiconductor

33932

FUNCTIONAL DESCRIPTION

FUNCTIONAL PIN DESCRIPTION

ENABLE INPUT/DISABLE INPUT 2 (EN/D2))

The EN/D2 pin performs the same function as D1 pin,

when it goes to a logic LOW the outputs are immediately tri-

stated. It is also used to place the device in a Sleep Mode so

as to consume very low currents. When the EN/D2 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 pull-down 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/D2 input becomes disconnected.

FEEDBACK (FB)

The 33932 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

Ω <RFB <300 Ω.

If PWM-ing is implemented using the disable pin input

(only D1), a small filter capacitor (~1.0 µF) may be required

in parallel with the RFB resistor to ground for spike

suppression.

33932 Datasheet(PDF) 12 Page - Freescale Semiconductor, Inc