BD9540EFV Datasheet, PDF (15/18 Pages) Rohm – 2ch Switching Regulators for Desktop PC

BD9540EFV
Technical Note
●Operation Notes
(1) Absolute Maximum Ratings
Use of the IC in excess of absolute maximum ratings (such as the input voltage or operating temperature range) may
result in damage to the IC. Assumptions should not be made regarding the state of the IC (e.g., short mode or open
mode) when such damage is suffered. If operational values are expected to exceed the maximum ratings for the device,
consider adding protective circuitry (such as fuses) to eliminate the risk of damaging the IC.
(2) Power Supply Polarity
Connecting the power supply in reverse polarity can cause damage to the IC. Take precautions when connecting the
power supply lines. An external power diode can be added.
(3) Power Supply Lines
In order to minimize noise, PCB layout should be designed such that separate, low-impedance power lines are routed to
the digital and analog blocks. Additionally, a coupling capacitor should be inserted between all power input pins and the
ground terminal. If electrolytic capacitors are used, keep in mind that their capacitance characteristics are reduced at
low temperatures.
(4) GND voltage
The potential of the GND pin must be the minimum potential in the system in all operating conditions.
(5) Thermal design
Use a thermal design that allows for a sufficient margin for power dissipation (Pd) under actual operating conditions.
(6) Inter-pin Shorts and Mounting Errors
Use caution when orienting and positioning the IC for mounting on printed circuit boards. Improper mounting may result
in damage to the IC. Shorts between output pins or between output pins and the power supply and GND pins caused by
poor soldering or foreign objects may result in damage to the IC.
(7) Operation in Strong Electromagnetic Fields
Using this product in strong electromagnetic fields may cause IC malfunction. Caution should be exercised in
applications where strong electromagnetic fields may be present.
(8) ASO - Area of Safe Operation
When using the IC, ensure that operating conditions do not exceed absolute maximum ratings or ASO of the output
transistors.
(9) Thermal shutdown (TSD) circuit
The IC incorporates a built-in thermal shutdown circuit, which is designed to turn the IC off completely in the event of
thermal overload. It is not designed to protect the IC from damage or guarantee its operation. ICs should not be used
after this function has activated, or in applications where the operation of this circuit is assumed.
BD9540EFV
TSD ON Temp. [°C] (typ.)
175
Hysteresis Temp. [°C] (typ.)
15
(10)Testing on application boards
When testing the IC on an application board, connecting a capacitor directly to a low-impedance pin may subject the IC
to stress. Always discharge capacitors completely after each process or step. The IC’s power supply should always be
turned off completely before connecting or removing it from a jig or fixture during the evaluation process. To prevent
damage from static discharge, ground the IC during assembly and use similar precautions during transport and storage.
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2009.04 - Rev.B