BD82103GWL_11 Datasheet, PDF (8/10 Pages) Rohm – Backlight LED Driver for Small LCD Panels (Charge Pump Type)

BD82103GWL
Technical Note
●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 IC 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 IC from thermal runaway as much as possible, is not aimed at the protection or guarantee of the IC.
Therefore, do not continuously use the IC with this circuit operating or use the IC 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) LDO
Use each output of LDO by the independence. Don’t use under the condition that each output is short-circuited
because it has the possibility that an operation becomes unstable.
(11) 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.
(12) About the rush current
For ICs with more than one power supply, it is possible that rush current may flow instantaneously due to the internal
powering sequence and delays. Therefore, give special consideration to power coupling capacitance, power wiring,
width of ground wiring, and routing of wiring.
(13) About the function description or application note or more.
The function description and the application notebook are the design materials to design a set. So, the contents of the
materials aren't always guaranteed. Please design application by having fully examination and evaluation include the
external elements.
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2011.06 - Rev.B