stk672-632b-e Sanyo Semiconductor Corporation, stk672-632b-e Datasheet - Page 14

• Manufacturer Part Number: stk672-632b-e
• Description: 2-phase Stepping Motor Driver
• Manufacturer: Sanyo Semiconductor Corporation

[Overcurrent detection]
[Overheat detection]
This hybrid IC is equipped with a function for detecting overcurrent that arises when the motor burns out or when there
is a short between the motor terminals.
Overcurrent detection occurs at 3.5A typ with the STK672-632B-E/630B-E, and 5.5A typ with the STK672-642B-
E/640B-E.
Overcurrent detection begins after an interval of no detection (a dead time of 5.5μs typ) during the initial ringing part
during PWM operations. The no detection interval is a period of time where overcurrent is not detected even if the
current exceeds I OH .
Rather than directly detecting the temperature of the semiconductor device, overheat detection detects the temperature
of the aluminum substrate (144°C typ).
Within the allowed operating range recommended in the specification manual, if a heat sink attached for the purpose of
reducing the operating substrate temperature, Tc, comes loose, the semiconductor can operate without breaking.
However, we cannot guarantee operations without breaking in the case of operations other than those recommended,
such as operations at a current exceeding I OH max that occurs before overcurrent detection is activated.
Set motor
current,
I OH
Vref= (R02÷ (R01+R02)) ×5V (or 3.3V)
I OH 1= (Vref÷4.9) ÷Rs
I OH 2= (V CC ÷R) × (1-e
⇒ Judgment standard: I OH 1>I OH 2
R01, R02, 5V (or 3.3V): See the Sample Application Circuit documents.
Rs: Current detection resistance value (Ω)
V CC : Motor supply voltage (V)
R: Motor winding resistance (Ω)
L: Motor winding inductance (H)
⇒ There is no problem if the I OH 2 obtained by substituting t = 30μs and the motor L and R values is smaller than
the current setting value I OH 1.
Output current
ENABLE
Normal operation
Vref
Current when motor terminals are shorted
No detection interval
(5.5μs typ)
-tR/L
)
PWM period
I OH 1: Motor current value to be set
I OH 2: Current value 30μs after the ENABLE high edge
Constant-current PWM operation must not be performed for 30μs or less.
STK672-632B-E
Operation when motor pins are shorted
MOSFET all OFF
5.5μs typ
Over-current detection
I OH max
No. A1738-14/24