74LS139 Dual 2-to-4 line Decoder/Demultiplexer IC (74139 IC) DIP-16 Package

The 74F521 is an expandable 8-bit comparator. It compares two words of up to eight bits each and provides a LOW output when the two words match bit for bit. The expansion input IA=B also serves as an active LOW enable input

Features :-

• Compares two 8-bit words in 6.5 ns typ
• Expandable to any word length
• 20-pin package

The 74F138 decoder accepts three binary weighted inputs (A0, A1, A2) and when enabled, provides eight mutually exclusive, active low outputs (Q0 – Q7). The device features three enable inputs; two active low (E0, E1) and one active high (E2). Every output will be high unless E0 and E1 are low and E2 is high. This multiple enable function allows easy parallel expansion of the device to 1–of–32 (5 lines to 32 lines) decoder with just four 74F138s and one inverter The device can be used as an eight output demultiplexer by using one of the active low enable inputs as the data input and the remaining enable inputs as strobes. Enable inputs not used must be permanently tied to their appropriate active high or active low state.

Features :-

• Demultiplexing capability
• Multiple input enable for easy expansion
• Ideal for memory chip select decoding
• Industrial temperature range available (–40°C to +85°C)

 

The 74F541 except that the inputs and outputs are on opposite sides of the package (see Connection Diagrams). This pinout arrangement makes these devices especially useful as output ports for microprocessors, allowing ease of layout and greater PC board density

Features :-

• 3-STATE outputs drive bus lines
• Inputs and outputs opposite side of package, allowing easier interface to microprocessors

The 74HC161 is a synchronous presettable binary counter with an internal look-head carry. Synchronous operation is provided by having all flip-flops clocked simultaneously on the positive-going edge of the clock (CP). The outputs (Q0 to Q3) of the counters maybe preset HIGH or LOW. A LOW at the parallel enable input (PE) disables the counting action and causes the data at the data inputs (D0 to D3) to be loaded into the counter on the positive-going edge of the clock. Preset takes place regardless of the levels at count enable inputs (CEP and CET). A LOW at the master reset input (MR) sets Q0 to Q3 LOW regardless of the levels at input pins CP, PE, CET and CEP (thus providing an asynchronous clear function). The look-ahead carry simplifies serial cascading of the counters. Both CEP and CET must be HIGH to count. The CET input is fed forward to enable the terminal count output (TC). The TC output thus enabled will produce a HIGH output pulse of a duration approximately equal to a HIGH output of Q0. This pulse can be used to enable the next cascaded stage. The maximum clock frequency for the cascaded counters is determined by the CP to TC propagation delay and CEP to CP set-up time ,according to the following formula: