- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄358881 > LMH6704MAX (NATIONAL SEMICONDUCTOR CORP) 650 MHz Progammable Gain Buffer with Disable PDF資料下載
參數(shù)資料
| 型號： | LMH6704MAX |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 音頻／視頻放大 |
| 英文描述： | 650 MHz Progammable Gain Buffer with Disable |
| 中文描述： | 1 CHANNEL, VIDEO AMPLIFIER, PDSO8 |
| 封裝： | SOIC-8 |
| 文件頁數(shù)： | 8/12頁 |
| 文件大小： | 774K |
| 代理商： | LMH6704MAX |
Application Section
(Continued)
UNITY GAIN COMPENSATION
With a current feedback PGB like the LMH6704, the feed-
back resistor is a compromise between the value needed for
stability at unity gain and the optimized value needed at a
gain of two. In standard open-loop current feedback opera-
tional amplifiers the feedback resistor, R
, is external and its
value can be adjusted to match the required gain. Since the
feedback resistor is integrated in the LMH6704, it is not
possible to adjust it’s value. However, we can employ the
circuit shown in
Figure 4
. This circuit modifies the noise gain
of the amplifier to eliminate the peaking associated with
using the circuit shown in
Figure 2
. The frequency response
is shown in
Figure 5
. The decreased peaking does come at
a price as the output referred voltage noise density in-
creases by a factor of 1.1.
OUTPUT VOLTAGE NOISE
Open-loop operational amplifiers specify three input referred
noise parameters: input voltage noise, non-inverting input
current noise, and inverting input current noise. These speci-
fications are used to calculate the total voltage noise pro-
duced at the output of the amplifier. The LMH6704 is a
closed loop amplifier with internal resistors, thus only the
non-inverting input current noise flows through external com-
ponents. All other noise sources are internal to the part.
There are four possible values for the noise at the output
depending on the gain configuration as shown in
Table 1
. For
more information on calculating noise in current feedback
amplifiers seeApplication Notes OA-12 andAN104 available
at www.national.com.
The total noise voltage at the output can be calculated using
the following formula:
For example, if an A
= +2 configuration is used with a
source impedance of 37.5
(parallel combination of 75
source and 75
termination impedances), where “I
” is
18.5pA/
and the output referred voltage noise (exclud-
ing non-inverting input noise current) can be found in
Table 1
below. The total noise (E
O
) at the output can be calculated
as:
TABLE 1. Measured Output Noise
Voltage
Gain (A
V
)
Output Referred Voltage Noise
(nV/
), excluding non-inverting
noise current
10.5
9.3
10.5
+2
+1
+1, alternate
method shown in
Figure 4
-1
Note: f
≥
100 kHz
10.5
ENABLE/DISABLE
The LMH6704 has a TTL logic compatible disable function.
Apply a logic low (
<
.8V) to the DS pin and the LMH6704 is
disabled. Apply a logic high (
>
2.0V), or let the pin float and
the LMH6704 is enabled. Voltage, not current, at the Disable
pin (DS) determines the enable/disable state. Care must be
exercised to prevent the disable pin voltage from going more
than .8V below the midpoint of the supply voltages (0V with
split supplies, V
+
/2 with single supply biasing). Doing so
could cause transistor Q1 to Zener resulting in damage to
the disable circuit (See
Figure 6
or the simplified internal
schematic diagram). The core amplifier is unaffected by this,
but the disable operation could become permanently slower
as a result.
20103632
FIGURE 5. Unity Gain Frequency Response
20103612
FIGURE 6. DIS Pin Simplified Schematic
L
www.national.com
8
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LMH6704MF | 650 MHz Progammable Gain Buffer with Disable |
| LMH6704MFX | 650 MHz Progammable Gain Buffer with Disable |
| LMH6704 | 650 MHz Progammable Gain Buffer with Disable |
| LMH6718MA | 5V High-Speed RS-232 Transceivers with 0.1uF Capacitors |
| LMH6718IMAX | Dual, High Output, Programmable Gain Buffer |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LMH6704MAX/NOPB | 功能描述:特殊用途放大器 RoHS:否 制造商:Texas Instruments 通道數(shù)量:Single 共模抑制比（最小值）: 輸入補償電壓: 工作電源電壓:3 V to 5.5 V 電源電流:5 mA 最大功率耗散: 最大工作溫度:+ 70 C 最小工作溫度:- 40 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-20 封裝:Reel |
| LMH6704MF | 功能描述:特殊用途放大器 RoHS:否 制造商:Texas Instruments 通道數(shù)量:Single 共模抑制比（最小值）: 輸入補償電壓: 工作電源電壓:3 V to 5.5 V 電源電流:5 mA 最大功率耗散: 最大工作溫度:+ 70 C 最小工作溫度:- 40 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-20 封裝:Reel |
| LMH6704MF/NOPB | 功能描述:特殊用途放大器 650MHz Selectable Gain Buffer RoHS:否 制造商:Texas Instruments 通道數(shù)量:Single 共模抑制比（最小值）: 輸入補償電壓: 工作電源電壓:3 V to 5.5 V 電源電流:5 mA 最大功率耗散: 最大工作溫度:+ 70 C 最小工作溫度:- 40 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-20 封裝:Reel |
| LMH6704MFX | 功能描述:特殊用途放大器 RoHS:否 制造商:Texas Instruments 通道數(shù)量:Single 共模抑制比（最小值）: 輸入補償電壓: 工作電源電壓:3 V to 5.5 V 電源電流:5 mA 最大功率耗散: 最大工作溫度:+ 70 C 最小工作溫度:- 40 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-20 封裝:Reel |
| LMH6704MFX/NOPB | 功能描述:特殊用途放大器 RoHS:否 制造商:Texas Instruments 通道數(shù)量:Single 共模抑制比（最小值）: 輸入補償電壓: 工作電源電壓:3 V to 5.5 V 電源電流:5 mA 最大功率耗散: 最大工作溫度:+ 70 C 最小工作溫度:- 40 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-20 封裝:Reel |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。