THM3561 Datasheet, PDF (13/21 Pages) THine Electronics, Inc. – Stepping Motor Driver with LVDS Interface

THM3561_Rev1.01_E
Functional Description (continued)
Over Current Protection (OCP) and Blanking Function Setting.
This device contains an Over Current Protection (OCP) function. The output transistor stops if a current of more
than 2.5A (typ.) flows through the output OUTA0 ~ OUTB1 pins (hereinafter, denoted as “OUT pin” in the case of
showing all driver output pins). This time, phase A and B work independently. The correlation between the pin at
which an over current has been detected and the pin at which the output stops is as given in table 14. This time,
FAULTn pin outputs Low level.
Table 14. Over Current Detect Function
Over current detect
Output pins
OUTA0/OUTA1
OUTB0/OUTB1
OUTA0
OUTA1
OUTB0
OUTB1
OFF (Hi-Z)
OFF (Hi-Z)
Keep state
Keep state
Keep state
Keep state
OFF (Hi-Z)
OFF (Hi-Z)
The over current protection function automatically recovers after about 1.28ms (typ.) after becoming effective. At
the time of automatic recovery, the FAULTn terminal stops Low level output and returns to High-Z output.
The blank function is the one by which the over current protection function becomes temporarily ineffective
(mask) at the time of change-over, in order to prevent the incorrect operation of the over current protection function
due to a spike current generated at the time of change-over of ON/OFF of the output driver. This function can be used
by taking BLANK_EN bit of register as 1. Set the blank function effective as 1.
The blank time is different for OFF→ON and ON→OFF of the output transistor. At the initial stage
(BLANK_SEL=0), OFF→ON time becomes 1CLK (0.625us, typ.) and ON→OFF time becomes 2CLK (1.25us, typ.)
of the built-in oscillator. In the case of BLANK_SEL=1, the OFF→ON time becomes 3CLK (1.875us, typ.) and
ON→OFF time becomes 4CLK (2.5us, typ.).
Thermal Shutdown (TSD)
This device contains a Thermal Shutdown (TSD) function. The OUT pin turns all channels OFF and the output of
VREG5 stops when the junction temperature of the product rises further exceeding the absolute maximum rated value.
This time, FAULTn pin outputs L level.
This function is designed for protection from smoke generation and fire and it actuates outside the absolute
maximum rated value. Do the thermal designing while keeping an adequate margin so that this function does not
actuate.
Under Voltage Lock Out (UVLO)
This device contains an Under Voltage Lock Out (UVLO) function for stable operation at the VCC and VREG5
pin.
This device stops operation when the VCC voltage falls below 7.5V (typ.), or VREG5 voltage falls below 3.5V (typ.).
Internal Regulator (VREG5)
This device contains a 5V (Typ.) output internal regulator (VREG5) for the internal circuit operation. VCC voltage
is depressed to about 5V inside this LSI.
The VREG5 pin usually bypasses to GND with 4.7uF for normal operation.
In addition, the VREG5 pin can be supplied to some external circuits (ex. sensor).
Supply current is 50mA (Typ.)
The VREG5 pin bypasses to GND with 10uF if it used with an external circuit.
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