1-Bit Loadable Cascadable Accumulator with Carry-In, Carry-Out, and Synchronous Reset

ACC1 can add or subtract a 1-bit unsigned-binary word to or from the contents of a 1-bit data register and store the results in the register. The register can be loaded with a 1-bit word. The synchronous reset (R) has priority over all other inputs and, when High, causes the output to go to logic level zero. Otherwise, clock (C) transitions are ignored when clock enable (CE) is Low. The default initial state of the flip-flop is zero.

Load

When the load input (L) is High, CE is ignored and the data on the input D0 is loaded into the 1-bit register.

Add

When control inputs ADD and CE are both High, the accumulator adds a 1-bit word (B0) and carry-in (CI) to the contents of the 1-bit register. The result is stored in the register and appears on output Q0 during the Low-to-High clock transition. The carry-out (CO) is not registered synchronously with the data output. CO allows cascading of ACC1s by connecting CO of one stage to CI of the next stage. In add mode, CO acts as a carry-out, and CO and CI are active-High.

Subtract

When ADD is Low and CE is High, the 1-bit word B0 and CI are subtracted from the contents of the register. The result is stored in the register and appears on output Q0 during the Low-to-High clock transition. The carry-out (CO) is not registered synchronously with the data output. CO allows cascading of ACC1s by connecting CO of one stage to CI of the next stage. In subtract mode, CO acts as a borrow, and CO and CI are active-Low.

Parameters

Parameter Description Units Default
DELAY Propagation delay. s DGTDELAY
IN_MODE Inputs mode.   IN
OUT_MODE Outputs mode.   OUT
IOMODEL The name of an I/O model, which describes the device‚Äôs loading and driving characteristics.   DGTDEFIOMODEL
POWER_NODE Digital power node name. Is the node used by the interface subcircuits which connect analog nodes to digital nodes.   $G_DPWR
GROUND_NODE Digital ground node name. Is the node used by the interface subcircuits which connect analog nodes to digital nodes.   $G_DGND