ta8435h TOSHIBA Semiconductor CORPORATION, ta8435h Datasheet - Page 6

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

OSCILLATOR FREQUENCY CALCULATION
The sawtooth oscillator (OSC) circuit consists of Q
less than the voltage of 2.5 V + V
charging through R1. Q
is equal to V
Assuming that V
connected to pin (4) and R1 is an on-chip 10 kΩ resistor, the OSC frequency is calculated as follows:
1 t
2 t
f
V
OSC
OSC
=
=
−
−
=
C
C
BE
=
=
OSC
OSC
t
· 5
2
5.15
(Q
1
−
⎡
⎢
⎣
·
·
1
2)
t
OSC
R
1
R
·C
−
1
+ V(
· 1
· 1
=
exp
OSC
l
l
C
= 1.4 V (t = t
n
n
3
OSC
SAT)
⎛
⎜ ⎜
⎝
−
and Q
1 (
1 (
(kHz)(C
C
−
(Q
−
OSC
(R
1.4
2.85
4),
5
1
1·
5
4
·R
)
BE
OSC
are turned on when V
l
which is approximately equal to 1.4 V. V
---------------------- (2),
)
n
1
-------------------- (3),
(Q
1 (
⎞
⎟ ⎟
⎠
1
:
⎤
⎥
⎦
) and = 2.85 V (t = t
2),
µF)
-------------------
−
1.4
a value that is approximately equal to 2.85 V. V
5
.
1
)
−
R
· 1
1
(1).
l
through Q
n
1 (
OSC
6
−
2.85
becomes 2.85 V (High level.) The Low level of V (4) pin
2
5
), and given that C
4
))
and R1 through R4. Q
OSC
is calculated by following equation:
OSC
2
is the external capacitance
is turned off when V
OSC
is increased by C
TA8435H/HQ
2006-3-2
OSC
OSC
is