TC78B015CFTG

2016-12-26

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13. Brake function

If high level is input into BRAKE terminal, the reverse brake works to stop the motor operation.

After the input signal into BRAKE terminal is changed from L level to H level during the motor rotation, the

reverse brake works until the position signal frequency becomes 40 Hz. When the position signal frequency

is less than 40 Hz, the motor will stop.

However, when the input signal into BRAKE terminal is changed from L level to H level under the condition

that the output duty command of TSP/VSP terminal is 0%, the operation sequence is shown as the below

table.

BRAKE

Functional description

High

Brake

Low or open

Normal operation

In case the input signal into BRAKE terminal is changed from L level to H level under the condition that the

output duty command of TSP/VSP terminal is 0%

Status

Brake sequence

Position signal frequency ≤ 40Hz

Short brake

Position signal frequency > 40Hz

Reverse brake → Short brake

14. Overvoltage monitoring function

When MVM = 2.0 V (typ.) or more, drive mode is 120-degree conduction.

MVM has 0.2 V (typ.) of hysteresis. If MVM < 1.8 V (typ.), drive restarts.

MVM

Function description

MVM ≥ 2.0 V (typ.)

120-degree commutation

MVM < 1.8 V (typ.)

150-degree commutation

15. Current limit circuit

Current limit circuit turns off upper side of the output transistors and limits the current. Driver restarts

just when PWM turns on.

Value of current limit is configured by the external resistance.

(Example) When 39 kΩ is set as the resistor (R), IOUT (typ.) = 39000/R = 39000/39000 ∼− 1.0 A

IR

ILIM

U

V

W

Detector

Detector

Detector

R = 39 kΩ (typ.)

VM

PGND1, PGND2

Detector

Detector

Detector

Current limit

circuit

Setting current

limit value