Texas Instruments

These 8-bit latches feature 3-state outputs designed specifically for driving highly capacitive or relatively low-impedance loads. The devices are particularly suitable for implementing buffer registers, I/O ports, bus drivers, and working registers. These 8-bit latches feature 3-state outputs designed specifically for driving highly capacitive or relatively low-impedance loads. The devices are particularly suitable for implementing buffer registers, I/O ports, bus drivers, and working registers.

The SN74ACT74-EP is a dual positive-edge-triggered D-type flip-flop. A low level at the preset (PRE\) or clear (CLR\) input sets or resets the outputs, regardless of the levels of the other inputs. When PRE\ and CLR\ are inactive (high), data at the data (D) input meeting the setup-time requirements is transferred to the outputs on the positive-going edge of the clock pulse. Clock triggering occurs at a voltage level and is not directly related to the rise time of the clock pulse. Following the hold-time interval, data at D can be changed without affecting the levels at the outputs. The SN74ACT74-EP is a dual positive-edge-triggered D-type flip-flop. A low level at the preset (PRE\) or clear (CLR\) input sets or resets the outputs, regardless of the levels of the other inputs. When PRE\ and CLR\ are inactive (high), data at the data (D) input meeting the setup-time requirements is transferred to the outputs on the positive-going edge of the clock pulse. Clock triggering occurs at a voltage level and is not directly related to the rise time of the clock pulse. Following the hold-time interval, data at D can be changed without affecting the levels at the outputs.

The SN74ACT7541 contains eight independent buffers with open-drain outputs. All channels can be simultaneously forced into the high-impedance state using either of the output enable inputs (OE1 or OE2). The SN74ACT7541 contains eight independent buffers with open-drain outputs. All channels can be simultaneously forced into the high-impedance state using either of the output enable inputs (OE1 or OE2).

The SN74ACT7541-Q1 contains eight independent buffers with open-drain outputs. All channels can be simultaneously forced into the high-impedance state using either of the output enable inputs (OE1 or OE2). The SN74ACT7541-Q1 contains eight independent buffers with open-drain outputs. All channels can be simultaneously forced into the high-impedance state using either of the output enable inputs (OE1 or OE2).

The SN74ACT7803 is a 512-word × 18-bit FIFO suited for buffering asynchronous datapaths up to 67-MHz clock rates and 12-ns access times. Two devices can be configured for bidirectional data buffering without additional logic. Multiple distributed VCCand GND pins, along with Texas Instruments patented output edge control (OECTM) circuit, dampen simultaneous switching noise. The write clock (WRTCLK) and read clock (RDCLK) are free running and can be asynchronous or coincident. Data is written to memory on the rising edge of WRTCLK when WRTEN1 is high, WRTEN2\ is low, and input ready (IR) is high. Data is read from memory on the rising edge of RDCLK when RDEN\, OE1\, and OE2\ are low and output ready (OR) is high. The first word written to memory is clocked through to the output buffer, regardless of the RDEN\, OE1\, and OE2\ levels. The OR flag indicates that valid data is present on the output buffer. The FIFO can be reset asynchronously to WRTCLK and RDCLK. RESET\ must be asserted while at least four WRTCLK and four RDCLK rising edges occur to clear the synchronizing registers. Resetting the FIFO initializes the IR, OR, and half-full (HF) flags low and the almost-full/almost-empty (AF/AE) flag high. The FIFO must be reset upon power up. The SN74ACT7803 is characterized for operation from 0°C to 70°C. The SN74ACT7803 is a 512-word × 18-bit FIFO suited for buffering asynchronous datapaths up to 67-MHz clock rates and 12-ns access times. Two devices can be configured for bidirectional data buffering without additional logic. Multiple distributed VCCand GND pins, along with Texas Instruments patented output edge control (OECTM) circuit, dampen simultaneous switching noise. The write clock (WRTCLK) and read clock (RDCLK) are free running and can be asynchronous or coincident. Data is written to memory on the rising edge of WRTCLK when WRTEN1 is high, WRTEN2\ is low, and input ready (IR) is high. Data is read from memory on the rising edge of RDCLK when RDEN\, OE1\, and OE2\ are low and output ready (OR) is high. The first word written to memory is clocked through to the output buffer, regardless of the RDEN\, OE1\, and OE2\ levels. The OR flag indicates that valid data is present on the output buffer. The FIFO can be reset asynchronously to WRTCLK and RDCLK. RESET\ must be asserted while at least four WRTCLK and four RDCLK rising edges occur to clear the synchronizing registers. Resetting the FIFO initializes the IR, OR, and half-full (HF) flags low and the almost-full/almost-empty (AF/AE) flag high. The FIFO must be reset upon power up. The SN74ACT7803 is characterized for operation from 0°C to 70°C.

A FIFO memory is a storage device that allows data to be written into and read from its array at independent data rates. The SN74ACT7806 is a 256-word by 18-bit FIFO for high speed and fast access times. It processes data at rates up to 50 MHz and access times of 15 ns in a bit-parallel format. Data is written into memory on a low-to-high transition at the load clock (LDCK) input and is read out on a low-to-high transition at the unload clock (UNCK) input. The memory is full when the number of words clocked in exceeds the number of words clocked out by 256. When the memory is full, LDCK signals have no effect on the data residing in memory. When the memory is empty, UNCK signals have no effect. Status of the FIFO memory is monitored by the full (FULL\), empty (EMPTY\), half-full (HF), and almost-full/almost-empty (AF/AE) flags. The FULL\ output is low when the memory is full and high when the memory is not full. The EMPTY\ output is low when the memory is empty and high when it is not empty. The HF output is high when the FIFO contains 128 or more words. The AF/AE status flag is a programmable flag. The first one or two low-to-high transitions of LDCK after reset are used to program the almost-empty offset value (X) and the almost-full offset value (Y) if program enable (PEN\) is low. The AF/AE flag is high when the FIFO contains X or fewer words or (256 - Y) or more words. The AF/AE flag is low when the FIFO contains between (X + 1) and (255 - Y) words. A low level on the reset (RESET\) input resets the internal stack pointers and sets FULL\ high, HF low, and EMPTY\ low. The Q outputs are not reset to any specific logic level. The FIFO must be reset upon power up.The first word loaded into empty memory causes EMPTY\ to go high and the data to appear on the Q outputs. It is important to note that the first word does not have to be unloaded. The data outputs are noninverting with respect to the data inputs and are in the high-impedance state when the output-enable (OE\) input is high. The SN74ACT7806 is characterized for operation from 0°C to 70°C. A FIFO memory is a storage device that allows data to be written into and read from its array at independent data rates. The SN74ACT7806 is a 256-word by 18-bit FIFO for high speed and fast access times. It processes data at rates up to 50 MHz and access times of 15 ns in a bit-parallel format. Data is written into memory on a low-to-high transition at the load clock (LDCK) input and is read out on a low-to-high transition at the unload clock (UNCK) input. The memory is full when the number of words clocked in exceeds the number of words clocked out by 256. When the memory is full, LDCK signals have no effect on the data residing in memory. When the memory is empty, UNCK signals have no effect. Status of the FIFO memory is monitored by the full (FULL\), empty (EMPTY\), half-full (HF), and almost-full/almost-empty (AF/AE) flags. The FULL\ output is low when the memory is full and high when the memory is not full. The EMPTY\ output is low when the memory is empty and high when it is not empty. The HF output is high when the FIFO contains 128 or more words. The AF/AE status flag is a programmable flag. The first one or two low-to-high transitions of LDCK after reset are used to program the almost-empty offset value (X) and the almost-full offset value (Y) if program enable (PEN\) is low. The AF/AE flag is high when the FIFO contains X or fewer words or (256 - Y) or more words. The AF/AE flag is low when the FIFO contains between (X + 1) and (255 - Y) words. A low level on the reset (RESET\) input resets the internal stack pointers and sets FULL\ high, HF low, and EMPTY\ low. The Q outputs are not reset to any specific logic level. The FIFO must be reset upon power up.The first word loaded into empty memory causes EMPTY\ to go high and the data to appear on the Q outputs. It is important to note that the first word does not have to be unloaded. The data outputs are noninverting with respect to the data inputs and are in the high-impedance state when the output-enable (OE\) input is high. The SN74ACT7806 is characterized for operation from 0°C to 70°C.

A FIFO memory is a storage device that allows data to be written into and read from its array at independent data rates. The SN74ACT7814 is a 64-word by 18-bit FIFO for high speed and fast access times. It processes data at rates up to 50 MHz and access times of 15 ns in a bit-parallel format. Data is written into memory on a low-to-high transition at the load clock (LDCK) input and is read out on a low-to-high transition at the unload clock (UNCK) input. The memory is full when the number of words clocked in exceeds the number of words clocked out by 64. When the memory is full, LDCK signals have no effect on the data residing in memory. When the memory is empty, UNCK signals have no effect. Status of the FIFO memory is monitored by the full (FULL\), empty (EMPTY\), half-full (HF), and almost-full/almost-empty (AF/AE) flags. The FULL\ output is low when the memory is full and high when the memory is not full. The EMPTY\ output is low when the memory is empty and high when it is not empty. The HF output is high when the FIFO contains 32 or more words and is low when it contains 31 or fewer words. The AF/AE status flag is a programmable flag. The first one or two low-to-high transitions of LDCK after reset are used to program the almost-empty offset value (X) and the almost-full offset value (Y) if program enable (PEN\) is low. The AF/AE flag is high when the FIFO contains X or fewer words or (64 - Y) or more words. The AF/AE flag is low when the FIFO contains between (X + 1) and (63 - Y) words. A low level on the reset (RESET\) input resets the internal stack pointers and sets FULL\ high, HF low, and EMPTY\ low. The Q outputs are not reset to any specific logic level. The FIFO must be reset upon power up. The first word loaded into empty memory causes EMPTY\ to go high and the data to appear on the Q outputs. It is important to note that the first word does not have to be unloaded. The data outputs are noninverting with respect to the data inputs and are in the high-impedance state when the output-enable (OE\) input is high. The SN74ACT7814 is characterized for operation from 0°C to 70°C. A FIFO memory is a storage device that allows data to be written into and read from its array at independent data rates. The SN74ACT7814 is a 64-word by 18-bit FIFO for high speed and fast access times. It processes data at rates up to 50 MHz and access times of 15 ns in a bit-parallel format. Data is written into memory on a low-to-high transition at the load clock (LDCK) input and is read out on a low-to-high transition at the unload clock (UNCK) input. The memory is full when the number of words clocked in exceeds the number of words clocked out by 64. When the memory is full, LDCK signals have no effect on the data residing in memory. When the memory is empty, UNCK signals have no effect. Status of the FIFO memory is monitored by the full (FULL\), empty (EMPTY\), half-full (HF), and almost-full/almost-empty (AF/AE) flags. The FULL\ output is low when the memory is full and high when the memory is not full. The EMPTY\ output is low when the memory is empty and high when it is not empty. The HF output is high when the FIFO contains 32 or more words and is low when it contains 31 or fewer words. The AF/AE status flag is a programmable flag. The first one or two low-to-high transitions of LDCK after reset are used to program the almost-empty offset value (X) and the almost-full offset value (Y) if program enable (PEN\) is low. The AF/AE flag is high when the FIFO contains X or fewer words or (64 - Y) or more words. The AF/AE flag is low when the FIFO contains between (X + 1) and (63 - Y) words. A low level on the reset (RESET\) input resets the internal stack pointers and sets FULL\ high, HF low, and EMPTY\ low. The Q outputs are not reset to any specific logic level. The FIFO must be reset upon power up. The first word loaded into empty memory causes EMPTY\ to go high and the data to appear on the Q outputs. It is important to note that the first word does not have to be unloaded. The data outputs are noninverting with respect to the data inputs and are in the high-impedance state when the output-enable (OE\) input is high. The SN74ACT7814 is characterized for operation from 0°C to 70°C.

The SN74ACT8541 contains eight independent buffers with 3-state outputs and Schmitt-trigger inputs. All channels can be simultaneously forced into the high-impedance state using either of the output enable inputs (OE1 or OE2). The SN74ACT8541 contains eight independent buffers with 3-state outputs and Schmitt-trigger inputs. All channels can be simultaneously forced into the high-impedance state using either of the output enable inputs (OE1 or OE2).

The SN74ACT8541-Q1 contains eight independent buffers with 3-state outputs and Schmitt-trigger inputs. All channels can be simultaneously forced into the high-impedance state using either of the output enable inputs (OE1 or OE2). The SN74ACT8541-Q1 contains eight independent buffers with 3-state outputs and Schmitt-trigger inputs. All channels can be simultaneously forced into the high-impedance state using either of the output enable inputs (OE1 or OE2).

The 'ACT8990 test-bus controllers (TBC) are members of the Texas Instruments SCOPETMtestability integrated-circuit family. This family of components supports IEEE Standard 1149.1-1990 (JTAG) boundary scan to facilitate testing of complex circuit-board assemblies. The 'ACT8990 differ from other SCOPETMintegrated circuits. Their function is to control the JTAG serial-test bus rather than being target boundary-scannable devices. The required signals of the JTAG serial-test bus - test clock (TCK), test mode select (TMS), test data input (TDI), and test data output (TDO) can be connected from the TBC to a target device without additional logic. This is done as a chain of IEEE Standard 1149.1-1990 boundary-scannable components that share the same serial-test bus. The TBC generates TMS and TDI signals for its target(s), receives TDO signals from its target(s), and buffers its test clock input (TCKI) to a test clock output (TCKO) for distribution to its target(s). The TMS, TDI, and TDO signals can be connected to a target directly or via a pipeline, with a retiming delay of up to 31 bits. Since the TBC can be configured to generate up to six separate TMS signals [TMS (5-0)], it can be used to control up to six target scan paths that are connected in parallel (i.e., sharing common TCK, TDI, and TDO signals). While most operations of the TBC are synchronous to TCKI, a test-off (TOFF\) input is provided for output control of the target interface, and a test-reset (TRST\) input is provided for hardware/software reset of the TBC. In addition, four event [EVENT (3-0)] I/Os are provided for asynchronous communication to target device(s). Each event has its own event generation/detection logic, and detected events can be counted by two 16-bit counters. The TBC operates under the control of a host microprocessor/microcontroller via the 5-bit address bus [ADRS (4-0)] and the 16-bit read/write data bus [DATA (15-0)]. Read (RD\) and write (WR\) strobes are implemented such that the critical host-interface timing is independent of the TCKI period. Any one of 24 registers can be addressed for read and/or write operations. In addition to control and status registers, the TBC contains two command registers, a read buffer, and a write buffer. Status of the TBC is transmitted to the host via ready (RDY\) and interrupt (INT\) outputs. Major commands can be issued by the host to cause the TBC to generate the TMS sequences necessary to move the target(s) from any stable test-access-port (TAP) controller state to any other stable TAP state, to execute instructions in the Run-Test/Idle TAP state, or to scan instruction or test data through the target(s). A 32-bit counter can be preset to allow a predetermined number of execution or scan operations. Serial data that appears at the selected TDI input (TDI1 or TDI0) is transferred into the read buffer, which can be read by the host to obtain up to 16 bits of the serial-data stream. Serial data that is transmitted from the TDO output is written by the host to the write buffer. The SN54ACT8990 is characterized for operation over the full military temperature range of -55°C to 125°C. The SN74ACT8990 is characterized for operation from 0°C to 70°C. NC - No internal connection The 'ACT8990 test-bus controllers (TBC) are members of the Texas Instruments SCOPETMtestability integrated-circuit family. This family of components supports IEEE Standard 1149.1-1990 (JTAG) boundary scan to facilitate testing of complex circuit-board assemblies. The 'ACT8990 differ from other SCOPETMintegrated circuits. Their function is to control the JTAG serial-test bus rather than being target boundary-scannable devices. The required signals of the JTAG serial-test bus - test clock (TCK), test mode select (TMS), test data input (TDI), and test data output (TDO) can be connected from the TBC to a target device without additional logic. This is done as a chain of IEEE Standard 1149.1-1990 boundary-scannable components that share the same serial-test bus. The TBC generates TMS and TDI signals for its target(s), receives TDO signals from its target(s), and buffers its test clock input (TCKI) to a test clock output (TCKO) for distribution to its target(s). The TMS, TDI, and TDO signals can be connected to a target directly or via a pipeline, with a retiming delay of up to 31 bits. Since the TBC can be configured to generate up to six separate TMS signals [TMS (5-0)], it can be used to control up to six target scan paths that are connected in parallel (i.e., sharing common TCK, TDI, and TDO signals). While most operations of the TBC are synchronous to TCKI, a test-off (TOFF\) input is provided for output control of the target interface, and a test-reset (TRST\) input is provided for hardware/software reset of the TBC. In addition, four event [EVENT (3-0)] I/Os are provided for asynchronous communication to target device(s). Each event has its own event generation/detection logic, and detected events can be counted by two 16-bit counters. The TBC operates under the control of a host microprocessor/microcontroller via the 5-bit address bus [ADRS (4-0)] and the 16-bit read/write data bus [DATA (15-0)]. Read (RD\) and write (WR\) strobes are implemented such that the critical host-interface timing is independent of the TCKI period. Any one of 24 registers can be addressed for read and/or write operations. In addition to control and status registers, the TBC contains two command registers, a read buffer, and a write buffer. Status of the TBC is transmitted to the host via ready (RDY\) and interrupt (INT\) outputs. Major commands can be issued by the host to cause the TBC to generate the TMS sequences necessary to move the target(s) from any stable test-access-port (TAP) controller state to any other stable TAP state, to execute instructions in the Run-Test/Idle TAP state, or to scan instruction or test data through the target(s). A 32-bit counter can be preset to allow a predetermined number of execution or scan operations. Serial data that appears at the selected TDI input (TDI1 or TDI0) is transferred into the read buffer, which can be read by the host to obtain up to 16 bits of the serial-data stream. Serial data that is transmitted from the TDO output is written by the host to the write buffer. The SN54ACT8990 is characterized for operation over the full military temperature range of -55°C to 125°C. The SN74ACT8990 is characterized for operation from 0°C to 70°C. NC - No internal connection