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PI6C9910
Zero-Delay Clock Buffer
Features
Zero input to output delay
Eight clock copies from one clock input
15 - 80 MHz output operation
Fifty percent duty cycle
Low skew (< 250ps typ.)
V
CC
= 5.0V +/- 10%, T
A
= 0擄 to 70擄
Low jitter (< 250 ps cycle to cycle), < 60ps RMS
Low noise unbalanced drive outputs (PI6C9910-5)
Low noise balanced drive outputs (PI6C9910A)
Packages available:
聳 24-pin 300 mil wide SOIC (S)
聳 24-pin 209 mil wide SSOP (H)
聲 Compatible with Cypress CY7B9910-5
聲
聲
聲
聲
聲
聲
聲
聲
聲
聲
Description
The PI6C9910 is a low-skew clock driver designed to simplify
clock distribution in systems requiring near synchronous clocks. A
typical application is in SDRAM modules. Each of the eight
outputs (Q0-Q7) can drive individual 50鈩?transmission lines with
minimal distortion or skew, and full 5V swing.
An on-chip phase-locked loop (PLL) synchronizes the feedback
(FB) to the reference (REF) input, achieving 聯(lián)zero-delay聰 buffered
outputs.
Inserting an external counter between any of the Qx outputs and the
FB pin allows for generation of eight synchronous clock copies
whose frequency is a multiple of a lower frequency REF input.
The voltage-controlled oscillator (VCO) frequency is determined
by the filtered ouput coming from the Phase/Frequency Detector.
The frequency select (FS) input sets the VCO operating range.
PI6C9910-5 has unbalanced output drivers (TTL), and is fully
compatible with the Cypress CY7B9910-5. The PI6C9910A features
balanced-drive outputs (CMOS) for improved rise/fall time
symmetry.
The FS and TEST inputs have internal pull-up resistors.
Test Mode
In normal operation the TEST pin is tied to ground. For testing
purposes it can have a removable jumper to ground or a 100鈩?/div>
pull-down resistor. When the TEST pin is driven HIGH, the VCO
output is disconnected, and all eight outputs (Q0-Q7) are directly
driven from the REF input.
Block Diagram
TEST
Pinout
FB
REF
Phase
Freq.
Det
Filter
Voltage
Controlled
Oscillator
FS
Q0
Q1
Q2
Q3
Q4
Q5
Q6
Q7
REF
V
CCQ
FS
NC
V
CCQ
V
CCN
Q
0
Q1
GND
Q2
Q3
V
CCN
1
2
3
4
5
6
7
8
9
10
11
12
24-Pin
S, H
24
23
22
21
20
19
18
17
16
15
14
13
GND
TEST
NC
GND
V
CCN
Q7
Q6
GND
Q5
Q4
V
CCN
FB
108
PS8341B
03/05/99
1
2
3
4
5
6
