AT16646
Fast Logic

16-Bit
Tri-State

Register

AT16646F
AT16646G

Features

Fastest Propagation Speeds in the Industry T

PD (F grade)

= 2.5 ns, T

PD (G grade)

= 2.0 ns

Maximum derating for capacitive loads 1.5ns/100 pF (F grade) and 1.1ns/100 pF

(G grade)

Very low ground bounce < 0.6 V @ V

=5.00 V, T

=25°C

Typical output skew

0.25ns

Bus Hold circuitry to retain last active state during Tri-State

Available in SSOP and TSSOP packages

Description

Atmel's AT16646 devices are 16-bit high speed, low power Tri-statable D type
registers, ideal for use in systems requiring both transparent and registered mode
functions. They are organized as two separate 8-bit bus transceivers. Data flow is
bi-directional, and can be controlled for multiplexed transmission between A bus and
B bus either directly or from the D registers by use of the direction control pin (xDir),
output enable (xOE), and select lines (xSAB and xSBA). Storage of data on the A bus
and B bus is controlled by the output pins. They have very low ground bounce and
excellent input noise rejection, giving the user stable signals in a high speed
environment. The Bus Hold feature eliminates the need for pull-up or pull-down
resistors and retains the last active state during a Tri-State event.

Functional Block Diagram

Pin Names

Descriptions

xDir, xOE

Output Enable Inputs

xCLKAB,xCLKBA

Clock Pulse Inputs

xSAB, xSBA

Output Data Source Select Inputs

Data Register A Inputs
Data Register B Outputs

Data Register B Inputs
Data Register A Outputs

Pin Configurations

1CLKAB

GND

1A2

1A3

1A5

1A6

1A8

2A2

GND

2A5

VCC

2A8

2SAB

2DIR

1SBA

1B1

VCC

1B4

GND

1B7

2B1

2B3

2B4

2B6

2B7

GND

2CLKBA

1CLKBA

GND

1B2

1B3

1B5

1B6

1B8

2B2

GND

2B5

VCC

2B8

2SBA

2OE

1DIR

1SAB

1A1

VCC

1A4

GND

1A7

2A1

2A3

2A4

2A6

2A7

GND

2CLKAB

SSOP/TSSOP

Top View

0757B

AT16646

5-21

Inputs

Data I/O

(2)

Operation or Function

xOE

xDir

xCLKAB

xCLKBA

xSAB

xSBA

H
H

X
X

H or L

X
X

Input

Isolation
Store A and B Data

L
L

X
X

H or L

X
X

Output

Input

Real Time B Data to A Bus
Stored B Data to A Bus

L
L

H
H

H or L

X
X

Input

Output

Real Time A Data to B Bus
Stored A Data to B Bus

Notes:

1. H = High voltage level, L = Low voltage level, X = Don't care,

= Low-to-High transition

2. The data output functions may be enabled or disabled by various signals at the xOE or xDir inputs. Data input functions

are always enabled, i.e. data at the bus pins will be stored on every LOW-to-HIGH transition on the clock inputs.

Function Table

(1)

Operating Temperature ........................ 0°C to +70°C

Storage Temperature ...................... -65°C to +150°C

Voltage on any Pin
with Respect to Ground................. -2.0 V to +7.0 V

(1)

Maximum Operating Voltage.............................. 6.0V

*NOTICE: Stresses beyond those listed under "Absolute

Maximum Ratings" may cause permanent damage to the
device. This is a stress rating only and functional operation
of the device at these or any other conditions beyond those
indicated in the operational sections of this specification is
not implied. Exposure to absolute maximum rating
conditions for extended periods may affect device reliability.

Notes:

1. Minimum voltage is -0.6 V dc which may

undershoot to -2.0 V for pulses of less than 20 ns.
Maximum output pin voltage is V

+0.75 V dc

which may overshoot to +7.0 V for pulses of less
than 20 ns.

Absolute Maximum Ratings*

Applicable over recommended operating range from T

= 0°C to +70°C, V

= +5.0V +/- 5% (unless otherwise noted)

Symbol

Parameter

Test Conditions

Min

Typ

Max

Units

Quiescent Power Supply
Current

= Max, V

= 3.4 V

0.8

1.2

Input High Voltage

2.0

Input Low Voltage

0.8

Input High Current (I/O Pins)

= V

Input Low Current (I/O Pins)

= GND

Output Leakage Current

(1)

Output High Voltage
F Grade only

= 4.75 V

= -10 mA

2.7

(2)

Output High Voltage
G Grade only

= 4.75 V

= -12 mA

2.7

Output Low Voltage (F Grade)

= 10 mA

0.55

Output Low Voltage (G Grade)

= 12 mA

0.55

Note:

1. F grade: At V

CC (max)

, the value of V

OH(max)

= 3.75 V and at V

CC(min)

, V

OH(max)

= 3.25 V

2. G grade: At V

CC (max)

, the value of V

OH(max)

= 3.75 V and at V

CC(min)

, V

OH(max)

= 3.35 V

5.0 Volt DC Characteristics

5-22

AT16646

Applicable over recommended operating range from T

= 0°C to +70°C, V

= 5.0V +/- 5% (unless otherwise noted)

Symbol

Parameter

Test Conditions

(1)

Min

Typ

Max

Units

PHL

PLH

Propagation Delay

CL = 50 pF

2.5

PZH

PZL

Output Enable Time

CL = 50 pF

7.4

PHZ

tPLZ

Output Disable Time

CL = 50 pF

6.4

(1)

Output Skew

CL = 50 pF

0.5

PHL

(1)

PLH

Propagation Delay vs Output Loading

1.3

1.5

ns/100 pF

Set-up Time Bus to Clock

CL = 50 pF

2.0

Hold Time Bus to Clock

CL = 50 pF

2.0

Note:

1. This parameter is guaranteed but not 100% tested.

AC Characteristics
AT16646F

Applicable over recommended operating range from T

= 0°C to +70°C, V

= 5.0V +/- 5% (unless otherwise noted)

Symbol

Parameter

Test Conditions

(1)

Min

Typ

Max

Units

PHL

PLH

Propagation Delay

CL = 50 pF

2.0

PZH

PZL

Output Enable Time

CL = 50 pF

7.4

PHZ

tPLZ

Output Disable Time

CL = 50 pF

5.8

(1)

Output Skew

CL = 50 pF

0.5

PHL

(1)

PLH

Propagation Delay vs Output Loading

0.9

1.1

ns/100 pF

Set-up Time Bus to Clock

CL = 50 pF

2.0

Hold Time Bus to Clock

CL = 50 pF

2.0

Note:

1. This parameter is guaranteed but not 100% tested.

AT16646G

Pulse

Generator

OUT

D.U.T.

50 pF

500

7.0V

500

Note:

1. Pulse Generator: Rate

1.0 MHz, t

2.5 ns,

2.5 ns.

2. AC tests are done with a single bit switching, and

timings need to be derated when multiple outputs are
switching in the same direction simultaneously. This
derating should not exceed 0.5 ns for 16 inputs switching
simultaneously.

Test Circuits

(1,2)

Test

Switch

Open Drain

Disable Low

Enable Low

Closed

All Other Tests

Open

Definitions:
C

= Load capacitance; Includes jig and probe capacitance.

= Termination resistance; Should be equal to Z

OUT

of the

Pulse Generator.

Switch Position

AT16646

5-23

-40

120

160

Time

-1.0

-0.5

0.0

0.5

1.0

1.5

2.0

Outp

ut, V

2.5

3.0

3.5

4.0

Output, V

IOL Pull Down Current

3.5

Time

VOLV

VOLP

-0.5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

olts

gnd - measured on
output with input
held constant

output

Ground Bounce for
High to Low Transitions

(1)

VOHP

VOHV

0.5

1.5

2.5

3.5

4.5

Time

l
t
s

vcc -
measured on
output with
input held
constant

output

Supply Bounce for
Low to High Transitions

(2)

Parameter

Value

Units

OLP

0.4

OLV

-0.26

OHV

- 0.13

OHP

+ 0.6

Note:

1. When multiple outputs are switched at the same time, rapidly changing current on the ground and V

path causes a

voltage to develop across the parasitic inductance of the wire bond and package pins. This occurrence is called
simultaneous switching noise. Atmel's AT16646 products have minimized this phenomenon as shown on the graph.
Output data is for 15 outputs switching simultaneously at a frequency of 1 MHz. The ground data is measured on the
one remaining output, which is set to logic low and will reflect any device ground movement.

2. As on the graph for Ground Bounce, a similar condition occurs for low to high transitions. Output data is for 15

outputs switching simultaneously at a frequency of 1 MHz. V

droop is measured on the one remaining output

pin, which is set to a logic high. This output will reflect any movement on the device V

Typical Values

5-24

AT16646

Part Number AT16646