bd63847 ROHM Co. Ltd., bd63847 Datasheet - Page 15

• Manufacturer Part Number: bd63847
• Description: Micro Step 36v Stepper Motor Drivers
• Manufacturer: ROHM Co. Ltd.

●Power dissipation
© 2010 ROHM Co., Ltd. All rights reserved.
BD63847/63843EFV
www.rohm.com
Please confirm that the IC’s chip temperature Tj is not over 150°C, while considering the IC’s power consumption (W),
package power (Pd) and ambient temperature (Ta). When Tj=150°C is exceeded the functions as a semiconductor do not
operate and problems such as parasitism and leaks occur. Constant use under these circumstances leads to deterioration
and eventually destruction of the IC. Tjmax=150°C must be strictly obeyed under all circumstances.
○Thermal Calculation
○Temperature Monitoring
V
The IC’s consumed power can be estimated roughly with the power supply voltage (V
ON resistance (R
The calculation method during FULL STEP drive, SLOW DECAY mode is shown here:
However, on duty: PWM on duty = t
t
measurement, or make an approximate calculation.
t
However, the thermal resistance valueθ
derating curve on P.16. Also, we are taking measurements of thermal resistance valueθ
Please feel free to contact our salesman. The calculated values above are only theoretical. For actual thermal design,
please perform sufficient thermal evaluation for the application board used, and create the thermal design with enough
margin to not exceed Tjmax=150°C.Although unnecessary with normal use, if the IC is to be used under especially
strict heat conditions, please consider externally attaching a Schottky diode between the motor output terminal and
GND to abate heat from the IC.
There is a way to directly measure the approximate chip temperature by using the TEST terminal. However,
temperature monitor using this TEST terminal is only for evaluation and experimenting, and must not be used in actual
usage conditions. TEST terminal has a protection diode for prevention from electrostatic discharge. The temperature
may be monitored using this protection diode.
(1) Measure the terminal voltage when a current of Idiode=50µA flows from the TEST terminal to the GND, without
(2) Measure the temperature characteristics of this terminal voltage. (Vf has a linear negative temperature factor
(3) Supply VCC, confirm the TEST terminal voltage while running the motor, and the chip temperature can be
BD63847EFV
BD63843EFV
on
chop
Consumed power of the Vcc [W] = V
Consumed power of the output DMOS [W] = (R
varies depending on the L and R values of the motor coil and the current set value. Please confirm by actual
supplying VCC to the IC. This measurement is of the Vf voltage inside the diode.
against the temperature.) With the results of these temperature characteristics, chip temperature may be calibrated
from the TEST terminal voltage.
approximated from the results of (2).
is the chopping period, which depends on the external CR. See P.8 for details.
Model Number
TEST
Junction temperature Tj = Ta[°C] + θ
Consumed power of total IC W_total [W] = ① + ②
Fig.6 Model diagram for measuring chip temperature
Idiode
ONH
Circuitry
､R
ONL
VCC
) and motor output current value (I
Upper PchDMOS ON Resistance
Circuitry
on
/ (t
CC
R
chop
[V]･I
ONH
ja
)
ja
[°C/W] differs greatly depending on circuit board conditions. Refer to the
[Ω] (Typ.)
0.50
1.25
[°C/W]･W_total [W]
CC
[A] ･･･････①
ONH
-Vf[mV]
15/19
[Ω] + R
+ (2･R
ONL
ONL
OUT
During output ON
[Ω])･I
[Ω])･I
25
).
During current decay
OUT
OUT
[A]
[A]
Lower NchDMOS ON Resistance
2
2
･2[ch]･on_duty
･2[ch]･(1 - on_duty) ･･･････②
R
ONL
150
[Ω] (Typ.)
0.35
0.65
CC
), circuit current (I
ja
of boards actually in use.
T
j
[°C]
Technical Note
2010.4 - Rev.A
CC
), output