TC78B002FTG 查看數據表（PDF） - Toshiba

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TC78B002FTG

TOSHIBA CMOS Integrated Circuit Silicon Monolithic

Toshiba 

4. OSC Frequency and PWM Frequency

Oscillation frequency is approximated by below formula.

fOSC = 1/(2C[F]×ROSC[Ω]) [Hz]= 1/(2×2.08e-12[F]×ROSC[Ω]) [Hz]

Oscillation frequency fOSC is 10MHz(typ) when external resistor ROSC is 24kΩ

PWM frequency fPWM=fOSC/400.

5. PWM Output Drive

In PWM drive, upper power transistor is turned on and off repeatedly.

TC78B002FTG

PWM ON

PWM ON → OFF

In switching phase, power transistor operates in below order.

VM

M

PWM ON

RS

RF

PWM ON

PWM OFF

Short brake

200ns (Design target value)

PWM OFF

PWM ON

6. Startup Sequence

Output starts when VSP pin at the voltage of VAD(L) or more. In order to ensure the starting torque, PWM

output is 50% duty when the motor rotating speed is lower than 5Hz (typ).

When output phase is switched during startup sequence, PWM OFF term of 1ms (typ) is inserted to reduce the

regenerating current to the power supply.

50% duty output

Duty is output by VSP voltage

14

2013-03-19

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