Datasheet
BU91796BMUF-M
MAX 80 Segments (SEG20×COM4)
Operational Notes
1.
2.
Reverse Connection of Power Supply
Connecting the power supply in reverse polarity can damage the IC. Take precautions against reverse polarity when
connecting the power supply, such as mounting an external diode between the power supply and the IC’s power
supply pins.
Power Supply Lines
Design the PCB layout pattern to provide low impedance supply lines. Separate the ground and supply lines of the
digital and analog blocks to prevent noise in the ground and supply lines of the digital block from affecting the analog
block. Furthermore, connect a capacitor to ground at all power supply pins. Consider the effect of temperature and
aging on the capacitance value when using electrolytic capacitors.
3.
4.
Ground Voltage
Ensure that no pins are at a voltage below that of the ground pin at any time, even during transient condition.
Ground Wiring Pattern
When using both small-signal and large-current ground traces, the two ground traces should be routed separately but
connected to a single ground at the reference point of the application board to avoid fluctuations in the small-signal
ground caused by large currents. Also ensure that the ground traces of external components do not cause variations
on the ground voltage. The ground lines must be as short and thick as possible to reduce line impedance.
5.
6.
Recommended Operating Conditions
The function and operation of the IC are guaranteed within the range specified by the recommended operating
conditions. The characteristic values are guaranteed only under the conditions of each item specified by the electrical
characteristics.
Inrush Current
When power is first supplied to the IC, it is possible that the internal logic may be unstable and inrush current may flow
instantaneously due to the internal powering sequence and delays, especially if the IC has more than one power
supply. Therefore, give special consideration to power coupling capacitance, power wiring, width of ground wiring, and
routing of connections.
7.
Testing on Application Boards
When testing the IC on an application board, connecting a capacitor directly to a low-impedance output 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 the test setup during the inspection
process. To prevent damage from static discharge, ground the IC during assembly and use similar precautions during
transport and storage.
8.
9.
Inter-pin Short and Mounting Errors
Ensure that the direction and position are correct when mounting the IC on the PCB. Incorrect mounting may result in
damaging the IC. Avoid nearby pins being shorted to each other especially to ground, power supply and output pin.
Inter-pin shorts could be due to many reasons such as metal particles, water droplets (in very humid environment) and
unintentional solder bridge deposited in between pins during assembly to name a few.
Unused Input Pins
Input pins of an IC are often connected to the gate of a MOS transistor. The gate has extremely high impedance and
extremely low capacitance. If left unconnected, the electric field from the outside can easily charge it. The small charge
acquired in this way is enough to produce a significant effect on the conduction through the transistor and cause
unexpected operation of the IC. So unless otherwise specified, unused input pins should be connected to the power
supply or ground line.
10. Regarding the Input Pin of the IC
In the construction of this IC, P-N junctions are inevitably formed creating parasitic diodes or transistors. The operation
of these parasitic elements can result in mutual interference among circuits, operational faults, or physical damage.
Therefore, conditions which cause these parasitic elements to operate, such as applying a voltage to an input pin
lower than the ground voltage should be avoided. Furthermore, do not apply a voltage to the input pins when no power
supply voltage is applied to the IC. Even if the power supply voltage is applied, make sure that the input pins have
voltages within the values specified in the electrical characteristics of this IC.
11. Ceramic Capacitor
When using a ceramic capacitor, determine a capacitance value considering the change of capacitance with
temperature and the decrease in nominal capacitance due to DC bias and others.
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12.Jun.2019 Rev.001
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