LS7362_15 Datasheet, PDF (1/6 Pages) LSI Computer Systems – BRUSHLESS DC MOTOR COMMUTATOR / CONTROLLER

LS7362
BRUSHLESS DC MOTOR COMMUTATOR / CONTROLLER
FEATURES:
Nov 2015
Speed control by Pulse Width Modulating (PWM) only
the low-side drivers reduces switching losses
in level converter circuitry for high voltage motors.
Open or closed loop motor speed control.
PIN ASSIGNMENT – TOP VIEW
+5V to +28V operation (VSS – VDD).
Externally selectable input to output code for 60°,
120°, 240°, or 300° electrical sensor spacing.
Three or four phase operation.
Analog speed control.
Forward/Reverse control.
Output enable control
Positive static braking
Over-current sensing
Six outputs drive switching bridge directly.
LS7362 (DIP), LS7362-S (SOIC)
LS7362-TS (TSSOP) – See connection diagram
DESCRIPTION:
The LS7362 is a MOS integrated circuit designed to generate the
signals necessary to control a three phase or four phase brushless
DC motor. It is the basic building block of a brushless DC motor
controller. The circuits respond to changes at the SENSE inputs,
originating at the motor position sensors, to provide electronic
commutation of the motor windings. Pulse width modulation (PWM)
of low-side drivers for motor speed control is accomplished through
the VTRIP input (Analog speed control) in conjunction with the
OSCILLATOR input. Over-current circuitry is provided to protect the
windings, associated drivers, and power supply. The LS7362
circuitry causes the external output drivers to switch off immediately
upon sensing the over-current condition, and on again only when
the over-current condition disappears and the positive edge of the
saw-tooth OSCILLATOR occurs. This limits the over-current sense
cycling to the chopping rate of the saw-tooth OSCILLATOR. A
positive braking feature is provided to effect rapid deceleration. The
LS7362 is designed for driving Bipolar and Field Effect Transistors.
Because only low-side drivers are pulse-width modulated, the
LS7362 is ideally suited in situations where the integrated circuit
interfaces with level converters to drive high voltage brushless DC
motors. By pulse width modulating the low-side drivers only, the
switch losses in the level conversion circuitry for the high-side
drivers is minimized. Figure 1 indicates how the level conversion is
accomplished.
The COMMON, Pin 5, is tied to the positive supply rail and
LS7362 Outputs 1, 2, and 3 are used to drive level converters Q101,
Q102 and Q103, respectively. Only the motor top side drivers
consisting of Q107, Q108 and Q109 which are connected to the
motor power supply, VM, will be subject to the high speed switching
currents that flow through the motor. The level converters are turned
on and off at the slower commutation rate.
INPUT / OUTPUT DESCRIPTION:
COMMUTATION SELECTS (Pins 1, 20)
These inputs are used to select the proper sequence of outputs
based on the electrical separation of the motor position sensors.
With both inputs low (logic zero), the sequence is adjusted for 60º
electrical separation, with CS2 high and CS1 low 120º separation
sequence is selected, with CS1 high and CS2 low 240º separation
sequence is selected and with CS1 and CS2 high the 300º
separation sequence is selected. Note that in all cases the external
output drivers are disabled for invalid SENSE input codes. Imternal
pull down resistors are provided at Pins 1 and 20 causing a logic
zero when these pins are left open.
7362-110515-1