Datasheet 搜索 > National Semiconductor（美国国家半导体） > LM6172IN 数据手册 > LM6172IN 数据手册 14/19 页
￥ 15.617
LM6172IN 数据手册 - National Semiconductor（美国国家半导体）
制造商:
National Semiconductor（美国国家半导体）
封装:
DIP
描述:
双高速，低功耗，低失真，电压反馈型放大器 Dual High Speed, Low Power, Low Distortion, Voltage Feedback Amplifiers
Pictures:
3D模型
符号图
焊盘图
引脚图
产品图
页面导航:
典型应用电路图在P17
原理图在P14
封装尺寸在P18P19
型号编码规则在P2
封装信息在P2
焊接温度在P3
功能描述在P1
技术参数、封装参数在P3P6
应用领域在P1
电气规格在P3P4P5P6P7P8P9P10P11P12P13
导航目录
LM6172IN数据手册
Page:
of 19 Go
若手册格式错乱，请下载阅览PDF原文件
LM6172 Simplified Schematic (Each Amplifier)
01258155
Application Notes
LM6172 PERFORMANCE DISCUSSION
The LM6172 is a dual high-speed, low power, voltage feed-
back amplifier. It is unity-gain stable and offers outstanding
performance with only 2.3mA of supply current per channel.
The combination of 100MHz unity-gain bandwidth, 3000V/µs
slew rate, 50mA per channel output current and other attrac-
tive features makes it easy to implement the LM6172 in
various applications. Quiescent power of the LM6172 is
138mW operating at
±
15V supply and 46mW at
±
5V supply.
LM6172 CIRCUIT OPERATION
The class AB input stage in LM6172 is fully symmetrical and
has a similar slewing characteristic to the current feedback
amplifiers. In the LM6172 Simplified Schematic, Q1 through
Q4 form the equivalent of the current feedback input buffer,
R
E
the equivalent of the feedback resistor, and stage A
buffers the inverting input. The triple-buffered output stage
isolates the gain stage from the load to provide low output
impedance.
LM6172 SLEW RATE CHARACTERISTIC
The slew rate of LM6172 is determined by the current avail-
able to charge and discharge an internal high impedance
node capacitor. This current is the differential input voltage
divided by the total degeneration resistor R
E
. Therefore, the
slew rate is proportional to the input voltage level, and the
higher slew rates are achievable in the lower gain configu-
rations.
When a very fast large signal pulse is applied to the input of
an amplifier, some overshoot or undershoot occurs. By plac-
ing an external series resistor such as 1kΩ to the input of
LM6172, the slew rate is reduced to help lower the over-
shoot, which reduces settling time.
REDUCING SETTLING TIME
The LM6172 has a very fast slew rate that causes overshoot
and undershoot. To reduce settling time on LM6172, a 1kΩ
resistor can be placed in series with the input signal to
decrease slew rate. A feedback capacitor can also be used
to reduce overshoot and undershoot. This feedback capaci-
tor serves as a zero to increase the stability of the amplifier
circuit. A 2pF feedback capacitor is recommended for initial
evaluation. When the LM6172 is configured as a buffer, a
feedback resistor of 1kΩ must be added in parallel to the
feedback capacitor.
Another possible source of overshoot and undershoot
comes from capacitive load at the output. Please see the
section “Driving Capacitive Loads” for more detail.
DRIVING CAPACITIVE LOADS
Amplifiers driving capacitive loads can oscillate or have ring-
ing at the output. To eliminate oscillation or reduce ringing,
an isolation resistor can be placed as shown in Figure 1. The
combination of the isolation resistor and the load capacitor
forms a pole to increase stability by adding more phase
margin to the overall system. The desired performance de-
pends on the value of the isolation resistor; the bigger the
isolation resistor, the more damped (slow) the pulse re-
sponse becomes. For LM6172, a 50Ω isolation resistor is
recommended for initial evaluation.
01258145
FIGURE 1. Isolation Resistor Used
to Drive Capacitive Load
LM6172
www.national.com 14
Downloaded from Elcodis.com electronic components distributor
器件 Datasheet 文档搜索
AiEMA 数据库涵盖高达 72,405,303 个元件的数据手册，每天更新 5,000 多个 PDF 文件
