LB11600JV_11 Datasheet, PDF (20/30 Pages) Sanyo Semicon Device – Brushless Motor Predriver IC for Automotive Applications

LB11600JV
LB11600JV Operation
1. Output Drive Circuit
The LB11600JV adopts direct PWM drive to minimize power loss in the output system. The output transistors are always
saturated when on and the motor drive power is adjusted by changing the output on duty. Output PWM switching is
applied the UH, VH, and WH output side circuits. Since the UL to WL and UH to WH outputs have the same output
configuration, either low side PWM or high side PWM drive can be implemented by using appropriate circuit structures
with the external output drive transistors. Since the reverse recovery time for the diodes connected to the non-PWM side
outputs can be a problem, care is required in selecting these diodes. (If diodes with a short reverse recovery time are not
used, through currents will flow at the instant the PWM side transistors are turned on.)
The UL to WL and UH to WH outputs go to the high-impedance state in the stopped state and when the supply voltage is
extremely low (i.e. lower than the allowable operating voltage). This means that workarounds (such as pull-down
resistors) are required so that leakage currents and other phenomenon do not cause incorrect operation in external circuits.
2. Power Saving Circuit
The LB11600JV goes to a power saving state in which power consumption is reduced when the S/S pin is set to the high
level. The power saving state cuts off the bias current from most of the circuits in the IC.
3. Notes on the PWM Frequency
The PWM frequency is set by the capacitance of the capacitor (C) connected to the PWM pin.
The formula for calculating the PWM frequency is shown below.
T2
V2
V1
T1
Formula (When VCC = 5V (typical))
Oscillator period:
T = T1 + T2 (s)
Threshold voltage:
Charge time:
V1 = 0.25 × VCC + 0.0975 = 1.35 (V) V2 = 0.6 × VCC = 3.0V (V)
T1 = C × (V2 - V1)/IC (s)
IC:
Charge current provided by the PWM pin: 45µA
Discharge time:
T2 = - C × Rin × ln (V1/V2) (s)
Rin:
PWM pin internal discharge resistor (2kΩ)
C:
External capacitor
Oscillator frequency: Fpwm = 1/T (Hz)
If a 1000pF capacitor is used, the oscillator frequency will be about 25kHz. If the PWM frequency is too low, the motor
may emit audible switching noise, and if it is too high, power loss in the output circuits will be excessive. We recommend
using a frequency in the range 15 to 50kHz. Connect the ground side of the external capacitor as close as possible to the IC
GND pin to minimize the influence of output noise and other problems.
No.8321-20/30