ta8435h TOSHIBA Semiconductor CORPORATION, ta8435h Datasheet - Page 24

• Manufacturer Part Number: ta8435h
• Description: Pwm Chopper-type Bipolar Stepping Motor Driver.
• Manufacturer: TOSHIBA Semiconductor CORPORATION

4.
5.
6.
7.
PWM oscillation frequency (external capacitor setting)
External Schottky diode
Power dissipation
Heatsink fin processing
PWM is controlled using this frequency.
flows to this parasitic diode. Unfortunately, this current has the effect of generating punch-through
current and micro-step waveform fluctuation. For this reason, be sure to connect a Schottky barrier
diode externally.
The IC power dissipation is determined by the following equation (where the Schottky diode is connected
between the output pin and GND):
The higher the ambient temperature, the smaller the power dissipation.
Check the P
The IC fin (rear) is electrically connected to the rear of the chip.
the fin or insulate it.
An external capacitor connected to the OSC pin is used to generate internally a sawtooth waveform.
Toshiba recommend 3300 pF for the capacitance, taking variations between ICs into consideration.
A parasitic diode can be supported on the lower side of the output. When PWM is controlled, current
This external diode can also reduce heat generated in the IC.
When current flows to the fin, the IC malfunctions.
If there is any possibility of a voltage being generated between the IC GND and the fin, either ground
P = V
t
ON
CC
D
= T
× I
-Ta curve, and be sure to design the heat dissipation with a sufficient margin.
CC
ON
+ VM × IM + I
/ T
S
(PWM control ON duty).
O
(t
ON
× V
SAT
24
−U + V
SAT
−L)
TA8435H/HQ
2006-3-2