MC100H644 查看數據表（PDF） - Motorola => Freescale

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MC100H644

68030/040 PECL to TTL Clock Driver

Motorola => Freescale 

MOTOROLA

SEMICONDUCTOR TECHNICAL DATA

68030/040

PECL-TTL Clock Driver

MC10H644

MC100H644

The MC10H/100H644 generates the necessary clocks for the 68030,

68040 and similar microprocessors. The device is functionally equivalent

to the H640, but with fewer outputs in a smaller outline 20–lead PLCC

package. It is guaranteed to meet the clock specifications required by the

68030 and 68040 in terms of part–to–part skew, within–part skew and

also duty cycle skew.

68030/040

PECL–TTL CLOCK

DRIVER

• Generates Clocks for 68030/040

• Meets 68030/040 Skew Requirements

• TTL or PECL Input Clock

• Extra TTL and ECL Power/Ground Pins

• Within Device Skew on Similar Paths is 0.5 ns

• Asynchronous Reset

• Single +5.0V Supply

The user has a choice of using either TTL or PECL (ECL referenced to

+5.0V) for the input clock. TTL clocks are typically used in present MPU

systems. However, as clock speeds increase to 50MHz and beyond, the

inherent superiority of ECL (particularly differential ECL) as a means of

clock signal distribution becomes increasingly evident. The H644 also

uses differential ECL internally to achieve its superior skew characteristic.

FN SUFFIX

PLASTIC PACKAGE

CASE 775–02

The H644 includes divide–by–two and divide–by–four stages, both to

achieve the necessary duty cycle and skew to generate MPU clocks as required. A typical 50MHz processor application would

use an input clock running at 100MHz, thus obtaining output clocks at 50MHz and 25MHz (see Logic Symbol).

The 10H version is compatible with MECL 10H™ ECL logic levels, while the 100H version is compatible with 100K levels

(referenced to +5.0V).

Function

Reset (R): LOW on RESET forces all Q outputs LOW and all Q outputs HIGH.

Synchronized Outputs: The device is designed to have the POS edges of the ÷2 and ÷4 outputs synchronized.

Select (SEL): LOW selects the ECL input source (DE/DE). HIGH selects the TTL input source (DT).

The H644 also contains circuitry to force a stable state of the ECL input differential pair, should both sides be left open. In this

case, the DE side of the input is pulled LOW, and DE goes HIGH.

MECL 10H is a trademark of Motorola, Inc.

Pinout: 20–Lead PLCC (Top View)

Q4 VT Q5 GT R

18 17 16 15 14

GT 19

13 VE

Q3 20

12 DE

GT 1

11 VBB

Q2 2

10 DE

GT 3

9 GE

4 5 6 78

Q1 VT Q0 SEL DT

11/93

© Motorola, Inc. 1995

2–1

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