APX9267
Application Information (Cont.)
PWM input
It is possible to change rotation speed of the motor by
switching high side output transistor. The on-duty of
switching depends on the input signal to PWM terminal.
(See Figure 4. PWM Input Waveform)
The value of resistor in the range of 1kΩ to 10kΩ is
recommended.
Thermal Consideration
Refer to “Maximum Power Dissipation vs. Ambient
Temperature”, the IC is safe to operate below the curve
and it will cause the thermal protection if the operating
area is above the line. For example, T
A
= 75°C, the
maximum power dissipation is about 0.35W.
The power dissipation can be calculated by the following
equation:
P
D
= (V
CC
- |V
OUT1
- V
OUT2
|) x I
OUT
+ V
CC
x I
CC
PWM
IN+
For example:
V
CC
= 5V, I
CC
= 4mA, I
OUT
= 270mA, V
OUT1
= 4.83V,
V
OUT2
= 0.17V, then P
D
= 0.111W
OUT1
The GND pin provides an electrical connection to ground
and channeling heat away. The printed circuit board (PCB)
forms a heat sink and dissipates most of the heat into
ambient air.
OUT2
FG
Figure 4. PWM Input Waveform
The input level of PWM terminal is
H : High side output transistor is ON
L : High side output transistor is OFF
When PWM terminal is open, it is equal to H.
FG Resistor
The value of the FG resistor could be decided by the fol-
lowing equation:
−
R
FG
=
V
CC
V
FG
I
FG
For example:
V
CC
=5V, I
FG
=3mA, V
FG
=0.2V, R
FG
=1.6kΩ
Copyright
©
ANPEC Electronics Corp.
Rev. A.6 - Mar., 2008
8
www.anpec.com.tw
ANPEC [ ANPEC ELECTRONICS COROPRATION ]
