
TPD4008K
2000-06-12 8/18
External Parts
Standard external parts are shown in the following table.
Part
Recommended Value
Purpose
Other
C
1
, C
2
, C
3
2.2
μ
F
Bootstrap capacitor
(Note1)
R
1
0.62
±
1% (1 W)
Current detection
(Note2)
C
4
1000 pF
±
5%
PWM frequency setup
(Note3)
R
2
27 k
±
5%
PWM frequency setup
(Note3)
C
5
10
μ
F
Control power supply stability
(Note4)
C
6
0.1
μ
F
V
REG
power supply stability
(Note4)
R
3
5.1 k
FG pin pull-up resistor
(Note5)
Note1: Although the required bootstrap capacitance value with the motor drive conditions, care must be taken to
keep the capacitor voltage above 5 V at startup and during drive. The capacitor is biased by 6 V (typ.) and
must be sufficiently derated for it.
Note2: The following formula shows the detection current: I
O
=
V
R
÷
RIS (V
R
=
0.5 V typ.)
Do not exceed a detection current of 900 mA when using the IC.
Note3: With the combination of Cos and R
REF
shown in the table, the PWM frequency is around 20 kHz. The IC
intrinsic error factor is around 10%.
The PWM frequency is broadly expressed by the following formula. (In this case, the stray capacitance of the
printed circuit board needs to be considered.)
f
PWM
=
0.65
÷
(Cos
×
R
REF
) [Hz]
R
REF
creates the reference current of the PWM triangular wave charge/discharge circuit. If R
REF
is set too
small it exceeds the current capacity of the IC internal circuits and the triangular wave distorts. Set R
REF
to
at least 9 k
.
Note4: When using the IC, some adjustment is required in accordance with the use environment. When mounting,
place as close to the base of the IC leads as possible to improve the noise elimination.
Note5: The FG pin is open drain. When using the FG pin, connect it to, for example, the CPU power supply (5 V) via
a pull-up resistor. Note that when the FG pin is connected to a power supply with an voltage equal or higher
than the V
CC
, a protector circuit is triggered so that the current flows continuously. If not using the FG pin,
connect to the GND.
Note6: If noise is detected on the Hall signal pin, add a CR filter.
(recommended 0.1
μ
F capacitor and 1 k
resistor)
Handling precautions
(1)
When switching the power supply to the circuit on/off, ensure that V
S
<
VV
S
OFF (all IGBT outputs
off). At that time, either the V
CC
or the V
BB
can be turned on/off first. Note that if the power supply is
switched off as described above, the IC may be destroyed if the current regeneration route to the V
BB
power supply is blocked when the V
BB
line is disconnected by a relay or similar while the motor is
still running.
The IS pin connecting the current detection resistor is connected to a comparator in the IC and also
functions as a sensor pin for detecting overcurrent. As a result, overvoltage caused by a surge, for
example, may destroy the circuit. Accordingly, be careful of handling the IC or of surges in its
application environment.
The triangular wave oscillator circuit, with externally connected C
OS
and R
REF
, charges and
discharges minute amounts of current. Therefore, subjecting the IC to noise when mounting it on the
board may distort the triangular wave or cause malfunction. To avoid this, attach external
components to the base of the IC leads or isolate them from any tracks or wiring which carries large
current.
The PWM of this IC is controlled by the ON/OFF state of the high-side IGBT.
(2)
(3)
(4)