CALIFORNIA MICRO DEVICES
PACDT
P/Active 1% Tolerance Dual Thévenin Termination Network
Features
• Minimal ground bounce, crosstalk
• Stable 1% absolute tolerance elements
• 16 terminating lines per QSOP package
• Saves board space and reduces assembly cost
Applications
• HSTL termination
• Thévenin termination
• ECL, TTL termination
Product Description
High speed logic devices like HSTL (High Speed
Transceiver Logic) demand unique, high speed bus
terminations. The dual Thévenin termination network
provides 16 terminating channels per package, and
optimizes signal integrity by reducing reflections and
ringing. The terminations are available in a range of
standard values and are ideal for use in HSTL busses.
As seen in the schematic, R1 is typically tied to V
CC
and
serves as a pull-up resistor, while R2 functions as a pull-
down resistor and is tied to ground (or the most negative
supply voltage). In addition, the equivalent Thévenin
resistance (R1 in parallel with R2) should match the
impedance of the trace. Ground-bounce and crosstalk
are virtually eliminated using a proprietary lead-frame
which includes four direct ground connections to the die
substrate, as well as four double-bonded connections to
V
CC
, for a total of 8 commons. In addition, the resistors
are trimmed to a tight absolute tolerance of 1% which
provides tight impedance-matching and results in greatly
reduced reflections. This unique proprietary design
provides optimal signal integrity.
STANDARD VALUES
Absolute Tolerance (R1 & R2)
TCR
Operating Temperature Range
Power Rating/Resistor
Crosstalk (see Test Circuit)
Package
±1%
±100ppm
0
˚
C to 70
˚
C
100mW
30mV TYP
24 Pin QSOP
BUS IMPEDANCE (Ω)
47
50
56
68
R1(Ω)
94
100
112
136
R2 (Ω) CODE
94
100
112
136
001
002
003
004
SCHEMATIC CONFIGURATION
24
V
CC
23
21
22 20
19
17
18 16
15
14
13
GND
1
2
3
4
5
6
7
8
9
10
11
12
STANDARD PART ORDERING INFORMATION
Package
R Code
001
002
003
004
Pin
24
24
24
24
Style
QSOP
QSOP
QSOP
QSOP
Ordering Part Number
Tubes
PAC001DTFQ/T
PAC002DTFQ/T
PAC003DTFQ/T
PAC004DTFQ/T
Tape & Reel
PAC001DTFQ/R
PAC002DTFQ/R
PAC003DTFQ/R
PAC004DTFQ/R
Part Marking
PAC001DTFQ
PAC002DTFQ
PAC003DTFQ
PAC004DTFQ
C1611100
© 2000 California Micro Devices Corp. All rights reserved.
215 Topaz Street, Milpitas, California 95035
11/19/2000
Tel: (408) 263-3214
Fax: (408) 263-7846
www.calmicro.com
1
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