74F842

Features:

• High speed parallel latches
• Extra data width for wide address/data paths or buses carrying parity
• High impedance NPN base input structure minimizes bus loading
• IIL is 20mA vs 1000A for AM29841 series
• Buffered control inputs to reduce AC effects
• Ideal where high speed, light loading, or increased fan-in are required as with MOS microprocessors
• Positive and negative over-shoots are clamped to ground
• 3-State outputs glitch free during power-up and power-down
• 48mA sink current
• Slim dual in-line 300 mil package
• Broadside pinout
• Pin-for-pin and function compatible with AMD AM29841-846 series


Pinout

Specifications

SYMBOL	PARAMETER	RATING	UNIT
VCC	Supply voltage	0.5 to +7.0	V
VIN	Input voltage	0.5 to +7.0	V
IIN	Input current	30 to +5	mA
VOUT	Voltage applied to output in high output state	0.5 to VCC	V
IOUT	Current applied to output in low output state	84	mA
Tamb	Operating free-air temperature range	0 to +70
Tstg	Storage temperature range	65 to +150

Description

The 74F842 bus interface latch series are designed to provide extra data width for wider address/data paths of buses carrying parity.

The 74F842 series are funcitonally an pin compatible to the AMD AM29841AM29846 series.

The 74F842 consists of ten D-type latches with 3-State outputs. The flip-flops appear transparent to the data when Latch Enable (LE) is High. This allows asynchronous operation, as the output transition follows the data in transition. On the LE High-to-Low transition, the data that meets the setup and hold time is latched.

Data appears on the bus when the Output Enable (OE) is Low.

When OE is High the output is in the High-impedance state.

The 74F842 is the inverted output version of the 74F841.

The 74F842 consists of nine D-type latches with 3-State outputs. In addition to the LE and OE pins, the 74F843 has a Master Reset (MR) pin and Preset (PRE) pin. These pins are ideal for parity bus interfacing in high performance systems. When MR is Low, the outputs are Low if OE is Low. When MR is High, data can be entered into the latch. When PRE is Low, the outputs are High, if OE is Low, PRE overrides MR.
The 74F845 consists of eight D-type latches with 3-State outputs. In addition to the LE, OE, MR and PRE pins, the 74F845 has two addtitional OE pins making a total of three Output Enables (OE0, OE1, OE2) pins.

The multiple Ouptut Enables (OE0, OE1, OE2) of the 74F842 allow multi-user control of the interface, e.g., CS, DMA, and RD/WR.

The 74F842 is the inverted output version of the 74F845.