- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄26831 > ML65244CS (FAIRCHILD SEMICONDUCTOR CORP) DUAL 4-BIT DRIVER, TRUE OUTPUT, PDSO20 PDF資料下載
參數(shù)資料
| 型號： | ML65244CS |
| 廠商： | FAIRCHILD SEMICONDUCTOR CORP |
| 元件分類： | 總線收發(fā)器 |
| 英文描述： | DUAL 4-BIT DRIVER, TRUE OUTPUT, PDSO20 |
| 封裝： | SOIC-20 |
| 文件頁數(shù)： | 6/8頁 |
| 文件大小： | 97K |
| 代理商： | ML65244CS |
ML65244/ML65L244
6
REV. 1.0 10/25/2000
The basic architecture of the ML65244 is shown in Figure
5. It is implemented on a 1.5m BiCMOS process.
However, in this particular circuit, all of the active
devices are NPNs — the fastest devices available in the
process.
In this circuit, there are two paths to the output. One
path sources current to the load capacitance when the
signal is asserted, and the other path sinks current from
the output when the signal is negated.
The assertion path is the emitter follower path consisting
of the level shift transistor Q1, the output transistor Q2,
and the bias resistor R8. It sources current to the output
through the 75 resistor R7 which is bypassed by another
NPN (not shown) during fast input transients. The
negation path is a current differencing op amp connected
in a follower configuration. The active components in
this amplifier are transistors Q3–Q7. R3–R6 are bias
resistors, and R1 and R2 are the feedback resistors. The
key to understanding the operation of the current
differencing op amp is to know that the currents in
transistors Q3 and Q5 are the same at all times and that
the voltages at the bases of Q4 and Q6 are roughly the
same. If the output is higher than the input, then an error
current will flow through R2. This error current will flow
into the base of Q6 and be multiplied by
β squared to the
collector of Q7, closing the loop. The larger the
discrepancy between the output and input, the larger the
feedback current, and the harder Q7 sinks current from
the load capacitor.
A number of MOSFETs are not shown in Figure 5. These
MOSFETs are used to three-state dormant buffers. For
instance, the feedback resistors R1 and R2 were
implemented as resistive transmission gates to ensure
that disabled buffers do not load the lines they are
connected to. Similarly, there is a PMOS in series with
R8 that is normally on but shuts off for disable. Other
MOSFETs have been included to ensure that disabled
buffers consume no power.
TERMINATION
R7 in Figure 5 also acts as a termination resistor. This 75
resistor is in series with the output and therefore helps
suppress noise caused by transmission line effects such as
reflections from mismatched impedances. System
designers using CMOS transceivers commonly have to
use external resistors in series with each transceiver
output to suppress this noise. Systems using the ML65244
or ML65L244 may not have to use these external
resistors.
APPLICATIONS
There are a wide variety of needs for extremely fast
buffers in high speed processor system designs like
Pentium, PowerPC, Mips, Sparc, Alpha and other RISC
processors. These applications are either in the cache
memory area or the main memory (DRAM) area. In
addition, fast buffers find applications in high speed
graphics and multimedia applications. The high
capacitive loading due to multiplexed address lines on
the system bus demand external buffers to take up the
excess drive current. The needed current to skew the
transitions between rise and fall times must be done
without adding excessive propagation delay. The
ML65244 and ML65L244 are equipped with Schottky
diodes to clean up ringing from overshoot and
undershoot caused by reflections in unterminated board
traces.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| ML65245CK | TTL/H/L SERIES, 8-BIT TRANSCEIVER, TRUE OUTPUT, PDSO20 |
| ML65541CK | TTL/H/L SERIES, 8-BIT DRIVER, TRUE OUTPUT, PDSO20 |
| ML65L541CK | TTL/H/L SERIES, 8-BIT DRIVER, TRUE OUTPUT, PDSO20 |
| ML65F16444CT | BICMOS SERIES, 16-BIT DRIVER, TRUE OUTPUT, PDSO48 |
| ML65F16444CR | BICMOS SERIES, 16-BIT DRIVER, TRUE OUTPUT, PDSO48 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ML65244CSX | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
| ML65245 | 制造商:MICRO-LINEAR 制造商全稱:MICRO-LINEAR 功能描述:High Speed Octal Buffer Transceivers |
| ML65245CK | 制造商:MICRO-LINEAR 制造商全稱:MICRO-LINEAR 功能描述:High Speed Octal Buffer Transceivers |
| ML65245CS | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
| ML6553 | 制造商:FAIRCHILD 制造商全稱:Fairchild Semiconductor 功能描述:Bus Termination Regulator |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。