OM9373 Ver la hoja de datos (PDF) - Omnirel Corp => IRF
Número de pieza
componentes Descripción
Fabricante
OM9373 Datasheet PDF : 12 Pages
| |||
SPEED INPUT (Pin 23) - This pin is connected to the
“+” input of a voltage comparator, whose threshold is
0.25Vdc. As long as the Speed Input is less than
0.25V, the direction latch is transparent. When the
Speed Input is greater than 0.25V, then the direction
latch inhibits all changes in direction. It is
recommended, especially while operating in the half
control mode, that the Tachometer Output is
connected to the Speed Input via a low-pass filter,
such that the direction latch is transparent only
when the motor is spinning very slowly. In this
case, the motor has too little stored energy to damage
the power devices during direction reversal.
DIRECTION INPUT (Pin 24) - This input is used to
select the motor direction. This input has an internal
protection feature: the logic-level present on the
Direction Input is first loaded into a direction latch, then
shifted through a two-bit shift register before
interfacing with the internal output phase driver logic
decoder. Also, protection circuitry detects when the
input and the output of the direction latch or the 2-bit
shift register are different, and inhibits the Phase
Outputs (i.e. Hi-Z) during those times. This feature
may be used to allow the motor to coast to a safe
speed before a direction reversal takes place. Power
stage cross-conduction (current "shoot-through" from
Vmotor to Ground through simultaneously enabled
pull-up and pull-down drivers) is prevented by the shift
register as it is clocked by the PWM oscillator, so that
a fixed delay of between one and two PWM oscillator
clock cycles occurs. This delay or "dead-time"
guarantees that power-stage cross-conduction will not
occur.
CURRENT SENSE OUTPUTS (CSH, Pin 25; CSL,
Pin 26) - The Current Sense Outputs produce a
differential voltage equal to the motor current times the
sense resistance value (5mΩ nominal). There is an
internal .018µF filter capacitor across pins 25 and 26,
and two 100Ω series resistors, one between each pin
and each end of the current sense resistor. To
configure the current sense amplifier for cycle-by-cycle
current limiting and/or overcurrent protection, connect
pin 25 to pin 12 (ISH) and pin 26 to pin 13 (ISL).
MOTOR RETURN (Pins 27 and 28) - These pins are
connected to the most negative terminal of the motor
supply (Vm-). This connection is electrically isolated
from the logic Ground internal to the OM9373 package
to minimize, if not eliminate, noise on the logic ground.
The connection to the logic ground is made by the user
external to the package (refer to Ground (pin 19)). In
order to minimize packaging losses and parasitic
effects, it is essential that both of these pins be firmly
connected to the motor supply Ground, with as short a
connection as physically possible.
OM9373
SOURCE (Pins 29, 34, 35, 39 and 40) -- The source
pins form the low-side connection of the pull-down
switches associated with each Phase Output.
Because of the switching current capability of the
OM9373, all 6 pins should be externally connected
together with a low impedance bus to minimize losses
and voltage differentials. Also, due to layout design
considerations, pin 29 is internally connected to the
"top" of the internal current-sense resistor.
PHASE OUTPUTS (Phase A, Pins 41 and 42; Phase
B, Pins 36 and 37; Phase C, Pins 31 and 32) --
These outputs are connected to either Vmotor via the
pull-up driver or Source via the pull-down driver,
depending upon the Hall-Effect and Direction Inputs
(see Commutation Truth Table). The two pins
associated with each Phase Output must be
connected to one of the three phases of the motor
driven by the OM9373.
VMOTOR (Pins 33, 38, and 43) - These pins are
connected to the most positive terminal of the motor
supply (Vm+). For proper operation, all three pins
must be connected together externally with a low
impedance power bus. The Vmotor power bus should
be bypassed with an adequately voltage-rated
ceramic capacitor, 0.1µF (typical), and a low-ESR
electrolytic capacitor, whose capacitance value can be
selected by the following: 10µF-per-Ampere of
average motor current from Vmotor to Motor Return.
Note: All connections, including the power bus
capacitor connections, must be made as close as
possible to the Vmotor and Motor Return pins to
minimize parasitic effects.
PACKAGE AND SCREENING OPTIONS
The OM9373 is offered in a hermetic flatpack package
as well as a plastic ring frame, low profile flatpack
package. The hermetic package, F-43, is shown in
Figure 1. The plastic ring frame, low profile package,
MP3-43L, has slightly larger dimensions and is shown
in Figure 2.
The hermetic version is offered in two standard
screening levels: a full military temperature range of -
55°C to +125°C with limited screening and with MIL-
STD-883 screening. The plastic ring frame version is
offered in an industrial temperature range of -40°C to
+85°C with limited screening.
The screening levels for the SFB, SF and SPP
versions are listed in the table below. All tests and
inspections are in accordance with those listed in MIL-
STD-883.
2.1 - 8
Share Link: 