SN74LVC16646
16-BIT BUS TRANSCEIVER AND REGISTER
WITH 3-STATE OUTPUTS
SCAS318B – NOVEMBER 1993 – REVISED JULY 1995
DGG OR DL PACKAGE
(TOP VIEW)
Member of the Texas Instruments
Widebus Family
EPIC (Enhanced-Performance Implanted
CMOS) Submicron Process
1
56
55
54
53
52
51
50
49
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
32
31
30
29
1DIR
1CLKAB
1SAB
GND
1OE
2
1CLKBA
1SBA
GND
1B1
Typical V
< 0.8 V at V
(Output Ground Bounce)
OLP
3
= 3.3 V, T = 25°C
CC
A
4
Typical V
> 2 V at V
(Output V
Undershoot)
5
1A1
1A2
OHV
CC
OH
= 3.3 V, T = 25°C
6
A
1B2
7
Latch-Up Performance Exceeds 250 mA
Per JEDEC Standard JESD-17
V
V
CC
CC
8
1A3
1A4
1A5
GND
1A6
1A7
1A8
2A1
2A2
2A3
GND
2A4
2A5
2A6
1B3
1B4
1B5
GND
1B6
1B7
1B8
2B1
2B2
2B3
GND
2B4
2B5
2B6
9
Bus Hold on Data Inputs Eliminates the
Need for External Pullup/Pulldown
Resistors
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
Package Options Include Plastic 300-mil
Shrink Small-Outline (DL) and Thin Shrink
Small-Outline (DGG) Packages
description
This 16-bit bus transceiver and register is
designed for low-voltage (3.3-V) V operation.
CC
The SN74LVC16646 can be used as two 8-bit
transceivers or one 16-bit transceiver. The device
consists of bus transceiver circuits, D-type
flip-flops, and control circuitry arranged for
multiplexed transmission of data directly from the
input bus or from the internal registers.
V
V
CC
CC
2A7
2A8
GND
2B7
2B8
GND
2SBA
2CLKBA
2OE
2SAB
2CLKAB
2DIR
Data on the A or B bus is clocked into the registers
on the low-to-high transition of the appropriate
clock (CLKAB or CLKBA) input. Figure 1
illustrates the four fundamental bus-management
functions that can be performed with the
SN74LVC16646.
Output-enable (OE) and direction-control (DIR) inputs control the transceiver functions. In the transceiver
mode, data present at the high-impedance port may be stored in either register or in both. The select-control
(SAB and SBA) inputs can multiplex stored and real-time (transparent mode) data. The circuitry used for select
control eliminates the typical decoding glitch that occurs in a multiplexer during the transition between stored
and real-time data. DIR determines which bus receives data when OE is low. In the isolation mode (OE high),
A data may be stored in one register and/or B data may be stored in the other register.
When an output function is disabled, the input function is still enabled and can be used to store and transmit
data. Only one of the two buses, A or B, may be driven at a time.
To ensure the high-impedance state during power up or power down, OE should be tied to V through a pullup
CC
resistor; the minimum value of the resistor is determined by the current-sinking capability of the driver.
Active bus-hold circuitry holds unused or floating data inputs at a valid logic level.
The SN74LVC16646 is characterized for operation from –40°C to 85°C.
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
EPIC and Widebus are trademarks of Texas Instruments Incorporated.
Copyright 1995, Texas Instruments Incorporated
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
1
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265