74AC11478

Supply voltage range, V_CC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.5 V to 7 V
Input voltage range, V_I (see Note 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . .0.5 V to VCC + 0.5 V
Output voltage range, V_O (see Note 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .0.5 V to VCC + 0.5 V
Input clamp current, I_IK (V_I < 0 or V_I > V_CC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .±20 mA
Output clamp current, I_OK (V_O < 0 or V_O > V_CC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .±50 mA
Continuous output current, I_O (V_O = 0 to V_CC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .±50 mA
Continuous current through V_CC or GND pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .±200 mA
Storage temperature range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . .65°C to 150°C

‡ Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under "recommended operating conditions" is not implied. Exposure to absolute-maximum-rated onditions for extended periods may affect device reliability.

NOTE 1: The input and output voltage ratings may be exceeded if the input and output clamp-current ratings are observed.

The 74AC11478 is an 8-bit dual-rank synchronizer circuit designed specifically for data synchronization applications in which the normal setup and hold time specifications are frequently violated.

Synchronization of two digital signals operating at different frequencies of the 74AC11478 is a common system problem. This problem is typically solved by synchronizing one of the signals to the local clock through a flip-flop. This solution,  however, causes the setup and hold time specifications associated with the flip-flop to be violated. When the setup or hold time of a flip-flop is violated, the output response is uncertain. A flip-flop is metastable if its output hangs up in the region between VIL and VIH. The metastable condition lasts until the flip-flop recovers into one of its two stable states. With conventional flip-flops, this recovery time can be longer than the specified maximum
propagation delay.

The problem of metastability is typically solved by adding an additional layer of synchronization. This dual-rank proach is employed in the 74AC11478. The probability of the second stage entering the metastable state is  ntially reduced by this dual-rank architecture. The 74AC11478 provides a one-chip solution for system esigners in asynchronous applications.

The 74AC11478 is characterized for operation from 40°C to 85°C.