Technical Note
25/27
www.rohm.com 2011.04 - Rev.
© 2011 ROHM Co., Ltd. All rights reserved.
BD2802GU
●Notes for Use
(1) Absolute Maximum Ratings
An excess in the absolute maximum ratings, such as supply voltage, temperature range of operating conditions, etc., can
break down devices, thus making impossible to identify breaking mode such as a short circuit or an open circuit. If any special
mode exceeding the absolute maximum ratings is assumed, consideration should be given to take physical safety measures
including the use of fuses, etc.
(2) Power supply and ground line
Design PCB pattern to provide low impedance for the wiring between the power supply and the ground lines. Pay attention to
the interference by common impedance of layout pattern when there are plural power supplies and ground lines.
Especially, when there are ground pattern for small signal and ground pattern for large current included the external
circuits, please separate each ground pattern. Furthermore, for all power supply pins to ICs, mount a capacitor between the
power supply and the ground pin. At the same time, in order to use a capacitor, thoroughly check to be sure the characteristics
of the capacitor to be used present no problem including the occurrence of capacity dropout at a low temperature, thus
determining the constant.
(3) Ground voltage
Make setting of the potential of the ground pin so that it will be maintained at the minimum in any operating state. Furthermore,
check to be sure no pins are at a potential lower than the ground voltage including an actual electric transient.
(4) Short circuit between pins and erroneous mounting
In order to mount ICs on a set PCB, pay thorough attention to the direction and offset of the ICs. Erroneous mounting
can break down the ICs. Furthermore, if a short circuit occurs due to foreign matters entering between pins or between
the pin and the power supply or the ground pin, the ICs can break down.
(5) Operation in strong electromagnetic field
Be noted that using ICs in the strong electromagnetic field can malfunction them.
(6) Input pins
In terms of the construction of IC, parasitic elements are inevitably formed in relation to potential. The operation of the parasitic
element can cause interference with circuit operation, thus resulting in a malfunction and then breakdown of the input pin.
Therefore, pay thorough attention not to handle the input pins, such as to apply to the input pins a voltage lower than the
ground respectively, so that any parasitic element will operate. Furthermore, do not apply a voltage to the input pins when no
power supply voltage is applied to the IC. In addition, even if the power supply voltage is applied, apply to the input pins a
voltage lower than the power supply voltage or within the guaranteed value of electrical characteristics.
(7) External capacitor
In order to use a ceramic capacitor as the external capacitor, determine the constant with consideration given to a degradation
in the nominal capacitance due to DC bias and changes in the capacitance due to temperature, etc.
(8) Thermal shutdown circuit (TSD)
This LSI builds in a thermal shutdown (TSD) circuit. When junction temperatures become detection temperature or
higher, the thermal shutdown circuit operates and turns a switch OFF. The thermal shutdown circuit, which is aimed at
isolating the LSI from thermal runaway as much as possible, is not aimed at the protection or guarantee of the LSI.
Therefore, do not continuously use the LSI with this circuit operating or use the LSI assuming its operation.
(9) Thermal design
Perform thermal design in which there are adequate margins by taking into account the permissible dissipation (Pd) in
actual states of use.
(10) About the pin for the test, the un-use pin
Prevent a problem from being in the pin for the test and the un-use pin under the state of actual use. Please refer to a
function manual and an application notebook. And, as for the pin that doesn't specially have an explanation, ask our
company person in charge.
(11) About the rush current
Because the rush current flows momentarily for internal logic instability caused by a power-on sequence or delay,
special care should be taken to the power supply coupling capacity, power supply, ground pattern wiring width and
wiring.
(12) About descriptions given in this document
Though the function description and application node are design documents prepared for application design, we don’t
take liability for descriptions given in these documents. Be sure to decide applications after thoroughly investigating
and evaluating the external devices as well as this BS2802GU LED driver.