M63155FP Renesas Electronics Corporation., M63155FP Datasheet - Page 19

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

M63155FP
9. Current Decay Method (DS)
TABLE 1. DS Selection Truth Table
DS
High
Low
The output MOS FETs are controlled by PWM signal as follows.
Rev.1.0, Sep.16.2003, page 19 of 40
The current decay method is determined by the input into the DS terminal. In slow-decay mode, only the high side
MOS FET is switched open during a PWM OFF (Low) cycle. The fast-decay mode switches both the high and low
side MOS FETs.
Table 1. gives the DS selection truth table.
D2
(1)Condition: Q1 is ON and Q4 is ON.
(2)Condition: Q4 is ON and Q2, Q1 are OFF.
(3)Condition: Q4 is ON and Q2, Q1 are OFF.
(4)Condition: Q4 is ON and Q2, Q1 are OFF.
The motor current I1 goes to RS through the
transistors Q1 and Q4.
The discharge current I2 goes through the
diode D2. This diode is a parasitic diode of the
output power FET.
The discharge current I2 keeps going through
the diode D2. Q2 keeps being OFF.
Likewise state (3), the discharge current I2
keeps going through the diode D2. Q2 keeps
being OFF.
Q2
Q1
(PWM OFF -> ON switching period)
(PWM ON period)
(PWM ON -> OFF switching period)
(PWM OFF period)
a) Slow-Decay Function
Fig. 9 Current Decay Method at the MOS FETs Control with PWM Signal
I1
I2
Q3
Q4
RS
Q5
Q6
Function Mode
Slow-Decay
Fast-Decay
VM
D2
Q2
(1)Condition: Q1 is ON and Q4 is ON
(2)Condition: Q1, Q4, Q2 and Q3 are OFF.
(3)Condition: Q1, Q4, Q2 and Q3 are OFF.
(4)Condition: Q1, Q4, Q2 and Q3 are OFF.
* When all the output power FETs are OFF, for example as
the phase change, the discharge current goes to VM through
these parasitic diodes.
Q1
The motor current I1 goes to RS through the
transistors Q1 and Q4.
The discharge current I2 goes through the
diode D2 and D3. This diode is a parasitic diode of
the output power FET.
The discharge current I2 keeps going through
the diode D2 and D3.
Likewise state (2), the discharge current I2 goes
through the diode D2 and D3.
(PWM OFF -> ON switching period)
(PWM ON period)
(PWM ON -> OFF switching period)
(PWM OFF period)
D3
I2
I1
b) Fast-Decay Function
Q3
Q4
RS
Q5
Q6
VM