OM9373 International Rectifier Corp., OM9373 Datasheet - Page 9

• Manufacturer Part Number: OM9373
• Description: Full-featured Power Module For Direct Drive Of 3-phase Brushless Dc Motor F-43 / Mp3-43l Packages
• Manufacturer: International Rectifier Corp.

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Pin Descriptions / Functionality
VCC (Pin 1) -- The Vcc Supply input provides bias
voltage to all of the internal control electronics
within the OM9373, and should be connected to a
nominal +15Vdc power source. High frequency
bypass capacitors (10uF polarized in parallel with
0.1uF ceramic are recommended) should be connected
as close as possible to pin 1 and Ground (pin 19).
ERROR AMPLIFIER (EA1- Input, Pin 2; EA1+
Input, Pin 4; EA1 Output, Pin 8) -- The Error
Amplifier is an uncommitted LM158-type operational
amplifier, providing the user with many external
control loop compensation options. This amplifier is
compensated for unity gain stability, so it can be
used as a unity gain input buffer to the internal
PWM comparator when pin 2 is connected to pin 8.
The output of the Error Amplifier is internally connected
to the PWM comparator's "-" input, simplifing external
layout connections.
+5V REFERENCE OUTPUT (Pin 5) -- This output
provides a temperature-compensated, regulated
voltage reference for critical external loads. It is
recommended that this pin be used to power the
external Hall-effect motor position sensors. By design,
the +5V reference must be in regulation before the
remainder of the control circuitry is activated. This
feature allows the Hall-effect sensors to become
powered and enabled before any Phase Output is
enabled in the OM9373 preventing damage at turn-
on. High-frequency bypass capacitors (10uF polarized
in parallel with 0.1uF ceramic are recommended)
should be connected as close as possible to pin 5
and Ground (pin 19).
SPARE AMPLIFIER (EA2- Input, Pin 6; EA2+
Input, Pin 3; EA2 Output, Pin 7) -- The Spare
Amplifier is an uncommitted LM158-type operational
amplifier, and in addition to the internal error
amplifier, provides the user with additional external
control loop compensation options. This amplifier is
also compensated for unity gain stability and it can
be used as a unity gain input buffer when pin 6 is
connected to pin 7. If the Spare Amplifier is unused,
pin 3 should be connected to Ground, and pin 6
should be connected to pin 7.
These inputs to the current-sense amplifier are inter
changeable and they can be used as differential
inputs. The differential voltage applied between pins
12 and 13 should be kept below +/-0.5Vdc to avoid
saturaion.
OSCILLATOR TIMING INPUT (Pin 10) -- The Oscillator
Timing Input sets a fixed PWM chopping frequency
by means
value is set to 75k:, connected from pin 10 to the +5V
Reference Output, and an internal capacitor (Cosc),
whose value is 1800pF, connected from pin 10 to
Ground. In custom
range of values for Rosc is 10k: to 100k:, and for
Cosc is 0.001uF to 0.01uF and the maximum operating
frequency should be kept below 20kHz. The approximate
oscillator frequency is:
The voltage waveform on pin 10 is a ramp whose
magnitude is approximately 1.2Vp-p, centered at
approximately 1.6Vdc. In addition to the voltage-
mode PWM control, pin 10 may be used for slope
compensation in current-mode control applications.
ISENSE (Pin 11) -- This pin is connected to the
output of the internal current-sense amplifier. It
drives a peak-current (cycle-by-cycle) comparator
which controls Phase Output chopping, and a fail-
safe current comparator which, in the event of an
output overcurrent condition, activates the soft-start
feature and disables the Phase Outputs until the
overcurrent condition is removed. The magnitude of
the voltage appearing at pin 11 is dependent upon
the voltages present at the current-sense amplifier
inputs, ISH and ISL:
CURRENT SENSE INPUTS (ISH, Pin 12; ISL, pin 13)
PWM INPUT (Pin 9) -- This pin is connected to the
"+" input of the internal PWM comparator. The PWM
output clears the internal PWM latch, which in turn
commands the Phase Outputs to chop. For voltage-
mode control systems, pin 9 may be connected to
the Oscillator Timing Input, pin 10.
V(Isense) = 2.5V + [2 x ABS (ISH - ISL)] [ V ]
f
o
of an internal resistor (Rosc), whose
=
( Rosc x Cosc )
applications, the recommended
2
[ Hz ]
OM9373
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