SN74ABT16821 20-Bit Bus Interface Flip-Flops With 3-State Outputs | TI.com

SN74ABT16821
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20-Bit Bus Interface Flip-Flops With 3-State Outputs

 

Description

These 20-bit flip-flops feature 3-state outputs designed specifically for driving highly capacitive or relatively low-impedance loads. They are particularly suitable for implementing wider buffer registers, I/O ports, bidirectional bus drivers with parity, and working registers.

The 'ABT16821 can be used as two 10-bit flip-flops or one 20-bit flip-flop. The 20 flip-flops are edge-triggered D-type flip-flops. On the positive transition of the clock (CLK) input, the device provides true data at the Q outputs.

A buffered output-enable () input can be used to place the ten outputs in either a normal logic state (high or low logic level) or a high-impedance state. In the high-impedance state, the outputs neither load nor drive the bus lines significantly. The high-impedance state and increased drive provide the capability to drive bus lines without need for interface or pullup components.

does not affect the internal operation of the flip-flops. Old data can be retained or new data can be entered while the outputs are in the high-impedance state.

To ensure the high-impedance state during power up or power down, should be tied to VCC through a pullup resistor; the minimum value of the resistor is determined by the current-sinking capability of the driver.

The SN54ABT16821 is characterized for operation over the full military temperature range of -55°C to 125°C. The SN74ABT16821 is characterized for operation from -40°C to 85°C.

 

 

Features

  • Members of the Texas Instruments WidebusTM Family
  • State-of-the-Art EPIC-IIBTM BiCMOS Design Significantly Reduces Power Dissipation
  • ESD Protection Exceeds 2000 V Per MIL-STD-883, Method 3015; Exceeds 200 V Using Machine Model (C = 200 pF, R = 0)
  • Typical VOLP (Output Ground Bounce) < 1 V at VCC = 5 V, TA = 25°C
  • Distributed VCC and GND Pin Configuration Minimizes High-Speed Switching Noise
  • Flow-Through Architecture Optimizes PCB Layout
  • High-Drive Outputs (-32-mA IOH, 64-mA IOL)
  • Package Options Include Plastic Thin Shrink Small-Outline (DGG), 300-mil Shrink Small-Outline (DL) Packages and 380-mil Fine-Pitch Ceramic Flat (WD) Package Using 25-mil Center-to-Center Spacings

    Widebus and EPIC-IIB are trademarks of Texas Instruments Incorporated.

Parametrics

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Part number Order Technology Family Input type Output type VCC (Min) (V) VCC (Max) (V) Channels (#) Clock Frequency (Max) (MHz) ICC (uA) IOL (Max) (mA) IOH (Max) (mA) Features Rating Package Group
SN74ABT16821 Order now ABT     TTL-Compatible CMOS     3-State     4.5     5.5     20     150     89000     64     -32     Very high speed (tpd 5-10ns)
Partial power down (Ioff)    
Catalog     SSOP | 56
TSSOP | 56