EDGE710 データシートの表示（PDF） - Semtech Corporation

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EDGE710

500 MHz Pin Electronics Driver,Window Comparator, and Load

Semtech Corporation 

Edge710

EDGE HIGH-PERFORMANCE PRODUCTS

Circuit Description (continued)

Window Comparator

Two comparators are connected on-chip to form a window

comparator to determine whether the DUT is high, low, or

in an indeterminant state. VINP is tied to the positive

inputs of both comparators.

The power supply driving the PECL pin must be capable of

sourcing all the current flowing out of the QA/QA* and QB/

QB* open emitter outputs.

The selection of either comparator A or B for the DUT high

versus the DUT low is arbitrary. However, because the

positive input is used on both comparators, the comparator

used to detect DUT low will have an inversion at it digital

outputs.

Comparator Input Protection

VINP connect to over-voltage diodes connected to the

positive and negative power supplies. These diodes are

sized to handle up to 100 mA current.

The figure below shows the correct polarity for the

comparator connections.

QA*

QA

IPD_C

PECL

CVA

VINP

Thermal Monitor

An on-chip thermal diode string of five diodes in series

exists (see figure below). This string allows accurate die

temperature measurements.

ANODE

Bias Current

QB

QB*

CVB

Thresholds

Temperature Coefficient = –9 mV / ˚C

CVA and CVB are the two comparator threshold levels.

These inputs are high impedance voltage controlled inputs

that determine at which VINP voltage the comparators

will change output states.

PECL Level Capability

PECL is the power supply level for the output stage of the

comparators. When connected to ground, the comparator

outputs will be standard ECL outputs. However, by making

PECL more positive, QA / QA* and QB / QB* will track

PECL and also become more positive.

CATHODE

An external bias current of 100 µA is injected through the

string, and the measured voltage corresponds to a specific

junction temperature with the following equation:

Tj[°C] = {(ANODE - CATHODE)/5 – .7752} / (–.0018).

By raising these voltage levels, the comparators may

connect directly with CMOS ICs.

 2000 Semtech Corp.

7

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