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The maximum operating frequency indicates the limit (speed) at which the IC can operate. The typical operating frequency limit of 7MHz can be minimized to 5MHz due to variations.
Products that can make the parallel outputs 'H' at the same time are the CMOS output type BU2152 and open drain output (requiring pull-up) types BU2099 and BU2092. The BU2152 sets the CLB pin to 'L' while the BU2099 and BU2092 sets the OE pin to 'H', with the outputs becoming 'H' asynchronously with other signals.Related Link:Technical Document
Products that can make the parallel output 'L' simultaneously are the CMOS output type BU2050 and open drain output type BU2098. Setting the /CLR pin to 'L' will allow the BU2050 to set all outputs to 'L' asynchronously with other input signals. And for the BU2098, all outputs become 'L' by power ON reset only when the power is turned ON.Related Link:Technical Document
The BU152 has no power ON reset function, so the initial values of the internal shift register will be random. Setting /CLB='L' makes it possible for all CMOS outputs to be simultaneously at 'H' but not 'H', regardless of other inputs. 'L' is not possible. But if the internal shift register is not set to that state beforehand initial random values will be output when /CLB='H'.
The longer the time the clock is near the threshold the greater the susceptibility to noise. If no upper limit is set for the input rise and fall times, there is a possibility of causing malfunction (i.e. erroneous clock count), so setting an upper limit will limit the effects of noise.
The maximum current of 25mA indicated in the datasheet is the maximum current that can flow to one output pin. The total current value must be within the total output current specification or the range not exceeding the total permissible loss.
Electrostatic protection diodes are inserted between the output and power supply and output and ground. When a voltage exceeding the power supply voltage is supplied to the output the diode turns ON and current flows from the output to the power supply, possibly causing damage, so please take care.