tb6558flg TOSHIBA Semiconductor CORPORATION, tb6558flg Datasheet - Page 5

• Manufacturer Part Number: tb6558flg
• Description: Dc Motor Driver
• Manufacturer: TOSHIBA Semiconductor CORPORATION

Other
PWM Chopper Control
winding is sensed via an external current-sense resistor. As the current increases, a voltage (VRF) develops
across the resistor, which is fed back to the comparator. At the predetermined reference voltage (V
comparator turns off (chops) the power supply.
internal CK signal as turn-off period. (The counter resets at the 11
transistors.
Turning on the power supply causes a current to flow into the motor coils. The peak current through the
When high-side output transistors are turned off, the TB6558FLG, by default, counts 10 rising edges of the
Based on this turn-off period, the TB6558FLG generates a PWM signal that turns on and off the output
The IN1 and IN2 input pins have a pull-down resistor of about 200 kΩ.
The STBY pin has a pull-down resistor of about 300 kΩ.
Internal clock
Timing Diagram of the PWM Chopper Circuit
10-bit counter
(The upper limit of the coil current (I O peak) can be calculated as: I O = V
PWM signal
Coil current
Generated
Off timer
V
OSC
VRF
limit
CK
Power on
1 2 3
4 5 6
(1 OSC cycle = 1 CK cycle)
ON
Input
Pull-down
resistor
5
OFF
limit
th
V
GND
rising edge of CK.)
CC
Counts 10 rising
/RNF.)
edge of CK
ON
OFF
TB6558FLG
2008-04-03
limit
Power off
ON
), the