M63155FP Renesas Electronics Corporation., M63155FP Datasheet - Page 21

• Manufacturer Part Number: M63155FP
• Description: 3 Phase Brushless Motor Controller
• Manufacturer: Renesas Electronics Corporation.

M63155FP
12. Braking Mode Selection (BRS)
TABLE 3. BRS Selection Truth Table
BRS
High
Low
13. Reset input (RST)
RST
High
Low
Rev.1.0, Sep.16.2003, page 21 of 40
TABLE 4. RST Selection Truth Table
1) In the normal mode (FLT output is “H”)
2) In the fault mode (FLT output is “L”)
This input used to enable the device. The “H” input allows the gate drive output to follow “Motor I/O truth table”.
The “L” input forces all gate drive output to 0V, coast(free-run) mode, and overrides the BRK state. And this “L”
input also resets the BRS state latched by the FLT “L” signal.
Table 4. gives the RST selection truth table.
The braking mode whether coast (free-run) or brake (short-brake) is selected by the BRS terminal. In the coast
(free-run) mode, all of the output terminals are floating. On the other side, in the brake (short-brake) mode, all of
the top side MOS FETs are turned off and all of the bottom side MOS FETs are turned on. This Braking Mode
provides a braking torque which depends on the motor speed.
In this case, the braking mode whether coast or brake is selected by the PWM signal irrelevant to the BRK
signal and the Current Control (RSS, CTL, TCL) function. The BRS state is latched by the FLT “L” signal. In
the BRS “L” state the coast mode is selected, while in the BRS “H” state the PWM signal determines the brake
mode.
And at this time, the positive power supply for the gate of the bottom side MOS FETs is provided by the charge-
pump external capacitor (Cgb; cf. Application circuit).
If gate drive to the bottom side MOS FETs is chopped via external control of the PWM pin, the minimum value
for Cgb is given in the following formula.
Coarse Cgb calculation
Cgb(min)= t x f x 3q(gate) / [Vcgb(initial) - Vcgb(final)]
for C in farads:
Table 3. gives the BRS selection truth table.
t = soft braking time (sec)
f = a chop frequency for PWM pin (Hz)
q(gate) = a electric charge stored in MOS FET gate (C)
Vcgb = delta V from initial to final (volts)
q(gate) : refer to the data sheet of selected MOS FET
* In brake mode, the three bottom side MOS FETs(UB,VB,WB) turns on simultaneously. So, it is needed
by 3q(gate).
normal mode (FLT;H)
BRK; H
Normal
Normal
Function Mode
Enable the device
Disable the device (Reset the BRS and FLT state)
BRK; L
Brake
Coast
fault mode (FLT;L)
PWM; H
Brake
Coast
PWM; L
Coast