The SN74ALS568A decade counter and ´ALS569A binary counters are programmable, count up or down, and offer both synchronous and asynchronous clearing. All synchronous functions are executed on the positive-going edge of the clock (CLK) input.
The clear function is initiated by applying a low level to either
asynchronous clear (ACLR\) or synchronous clear (SCLR\). Asynchronous
(direct) clearing overrides all other functions of the device, while
synchronous clearing overrides only the other synchronous functions.
Data is loaded from the A, B, C, and D inputs by holding load (
) low during a positive-going clock
transition. The counting function is enabled only when enable P
(ENP\) and enable T (ENT\) are low and ACLR\, SCLR\, and are high. The up/down (U/D\) input
controls the direction of the count. These counters count up when
U/D\ is high and count down when U/D\ is low.
A high level at the output-enable (
) input forces the Q outputs into
the high-impedance state, and a low level enables those outputs.
Counting is independent of .
ENT\ is fed forward to enable the ripple-carry output (RCO\) to
produce a low-level pulse while the count is zero (all Q outputs low)
when counting down or maximum (9 or 15) when counting up. The clocked
carry output (CCO\) produces a low-level pulse for a duration equal
to that of the low level of the clock when 
is low and the counter is enabled
(both ENP\ and ENT\ are low); otherwise, CCO\ is high. CCO\ does not
have the glitches commonly associated with a ripple-carry output.
Cascading is normally accomplished by connecting or CCO\ of the first counter to
ENT\ of the next counter. However, for very high-speed counting, should be used for cascading since
CCO\ does not become active until the clock returns to the low level.
The SN54ALS569A is characterized for operation over the full military temperature range of -55°C to 125°C. The SN74ALS568A and SN74ALS569A are characterized for operation from 0°C to 70°C.
| Tipo | Título | Fecha | ||
|---|---|---|---|---|
| * | Data sheet | Synchronous 4-Bit Up/Down Decade And Binary Counters With 3-State Outputs datasheet (Rev. A) | 01 ene 1995 | |
| Selection guide | Logic Guide (Rev. AB) | 12 jun 2017 | ||
| Application note | Understanding and Interpreting Standard-Logic Data Sheets (Rev. C) | 02 dic 2015 | ||
| User guide | LOGIC Pocket Data Book (Rev. B) | 16 ene 2007 | ||
| Application note | Semiconductor Packing Material Electrostatic Discharge (ESD) Protection | 08 jul 2004 | ||
| Application note | TI IBIS File Creation, Validation, and Distribution Processes | 29 ago 2002 | ||
| Application note | Bus-Interface Devices With Output-Damping Resistors Or Reduced-Drive Outputs (Rev. A) | 01 ago 1997 | ||
| Application note | Designing With Logic (Rev. C) | 01 jun 1997 | ||
| Application note | Input and Output Characteristics of Digital Integrated Circuits | 01 oct 1996 | ||
| Application note | Live Insertion | 01 oct 1996 | ||
| Application note | Advanced Schottky (ALS and AS) Logic Families | 01 ago 1995 |
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| Paquete | Pasadores | Descargar |
|---|---|---|
| PDIP (N) | 20 | Ver opciones |
| SOIC (DW) | 20 | Ver opciones |
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