LB11600JV_11 Datasheet, PDF (21/30 Pages) Sanyo Semicon Device – Brushless Motor Predriver IC for Automotive Applications

LB11600JV
4. Notes on PWM Drive Methods
The output duty can be controlled by any of the following methods.
• Control by Comparing the TOC Pin Voltage with the PWM Oscillator Waveform
This method sets the UH, VH, and WH output duty by comparing the TOC pin voltage with the PWM oscillator
waveform. When the TOC pin voltage falls below 1.35V (typical), the duty will be 0%, and when it rises above 3.0V
(typical), the duty will be 100%. Since the TOC pin is the control amplifier's output pin, it is not possible to directly input
a control voltage to the TOC pin. Therefore, the control amplifier is normally used as a buffer amplifier (by connecting the
CTL- pin to the TOC pin) and inputting a DC voltage to the CTL+ pin. (This causes the TOC pin voltage to become the
same as the CTL+ pin voltage.)
In this case, the output duty will increase as the CTL+ pin voltage becomes higher. Since the motor will be driven if the
CTL+ pin is in the open state, a pull-down resistor must be connected to the CTL+ pin if it is not desirable to drive the
motor when the input is in the open state.
If the CTL+ pin is used for motor control, set the PWMIN pin to the low level or short it to ground.
• Pulse Control Using the PWMIN Pin
A pulse input can be applied to the PWMIN pin and the duty of that signal used to _{To the}
control the output.
PWMIN pin
When a low-level input voltage is applied to the PWMIN pin the output will be on,
and when a high-level input voltage is applied the output will be off. When the
PWMIN pin is open, it goes to the high level and the output will be turned off. If
the inverse input logic is required, use an external npn transistor as shown in the
figure.
Pulse input
If the PWMIN pin is used for control, connect the CTL- pin to ground and
connect the CTL- pin to the TOC pin.
A 1000pF capacitor must be connected to the PWM pin even when the PWMIN pin is used for control.
• PWMRE Pin Input Pulse Reset
To prevent incorrect operation of the constraint protection circuit when the VCC power supply is started or when the
motor is stopped (the constraint protection circuit will operate immediately if the CSD pin potential is low), that is to
assure that the CSD pin is set to the high-level voltage reliably (by assuring the capacitor charge time), a reset period
(outputs off, the rapid charge time for the CSD pin) is set up by a resistor and capacitor connected to the PWMRE pin.
When the motor is controlled by either the CTL+ pin or by pulses input to the PWMIN pin, output to the motor is not
provided immediately. Rather the output remains in the off state (the reset period) until the charge/discharge potential due
to the on/off operation set by the input pulse duty width, the PWMRE pin charge current, and the capacitor and resistor
connected to the PWMRE pin rises above 1.25V (typical). The IC enters operating mode when the PWMRE potential is
over 1.25V (typical), and the output goes to the off state (reset state) when the PWMRE potential falls below 0.55V
(typical) in the input pulse off state.
The IC operates with the outputs on (UH, VH, and WH), when the PWMRE potential is over 1.25V (typical) and the CSD
pin potential is over 0.76 × VCC (3.8V typical when VCC = 5V).
See the timing chart for startup and the input off state.
The formula for setting the reset time (Trest) and the timing charts are shown on the following pages.
<Reset time (Trest f) due to the PWMRE pin (PWMIN input mode) when VCC = 5V>
The rise potential (V1) and the fall potential (V2) due to the on/off duty ratio when a PWMIN input is used:
When on: V1 = (V0 - Ipwmre × R) × e-t1/RC + Ipwmre × R
When off: V2 = V1 × e-t2/RC = ΔV
Ipwmre: PWMRE pin charge current: 200µA (typical)
V0:
PWMRE initial potential: 0V
C:
PWMRE pin external capacitor
R:
PWMRE pin external resistor
t1:
PWMIN input duty on time
t2:
PWMIN input duty off time
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