These 8-bit latches are designed specifically for storing the
contents of the input data bus and providing the capability of
reading back the stored data onto the input data bus. The Q outputs
are designed with bus-driving capability.
The edge-triggered flip-flops enter the data on the low-to-high
transition of the clock (CLK) input when the enable () input is low. Data can be read
back onto the data inputs by taking the read () input low, in addition to having
low. When EN\ is high, both the
read-back and write modes are disabled. Transitions on should only be made with CLK high
to prevent false clocking.
The polarity of the Q outputs can be controlled by the polarity
(T/C\) input. When T/C\ is high, Q is the same as is stored in the
flip-flops. When T/C\ is low, the output data is inverted. The Q
outputs can be placed in the high-impedance state by taking the
output-enable () input high.
affect the internal operation of the register. Old data can be
retained or new data can be entered while the outputs are off.
A low level at the clear ()
input resets the internal registers low. The clear function is
asynchronous and overrides all other register functions.
The -1 version of the SN74ALS996 is identical to the standard
version, except that the recommended maximum IOL for the
-1 version is increased to 48 mA. There is no -1 version of the
The SN54ALS996 is characterized for operation over the full
military temperature range of -55°C to 125°C. The
SN74ALS996 is characterized for operation from 0°C to 70°C.