Datasheet 搜索 > 温度传感器 > Maxim Integrated（美信） > MAX6670AUB70+ 数据手册 > MAX6670AUB70+ 开发手册 1/3 页
器件3D模型￥ 11.319
MAX6670AUB70+ 开发手册 - Maxim Integrated（美信）
制造商:
Maxim Integrated（美信）
分类:
温度传感器
封装:
uMAX-10
Pictures:
3D模型
符号图
焊盘图
引脚图
产品图
MAX6670AUB70+数据手册
Page:
of 3 Go
若手册格式错乱，请下载阅览PDF原文件
Maxim > Design Support > Technical Documents > Application Notes > Automotive > APP 3149
Maxim > Design Support > Technical Documents > Application Notes > Temperature Sensors and Thermal Management > APP 3149
Keywords: PWM, buffer, convert, amplify, amplifier, fan, speed, controlller
APPLICATION NOTE 3149
Circuit Converts PWM to Amplified and Buffered
Linear Signal
Jun 16, 2004
Abstract: A simple circuit converts a low-voltage PWM signal to an amplified and buffered linear output.
Intended for fan speed control, it allows a 3.3V input to provide linear control of a 12V fan.
Maxim makes a variety of fan speed controllers with PWM outputs to control fan speed as a function of
temperature. These work by cycling the power to the fan off and on. The fan's speed with the duty cycle
setting the fan's speed. In many situations the typical application circuit for these is adequate. However, some
situation require a constant power supply to the fan due to audible noise from the fan modulation.
If the noise from cycling the fan's power is too much, consider the circuit of Figure 1. In this case,
complementary pair of BJTs (Q1) and a PMOS FET (Q2) create a linear amplifier.
Figure 1. A simple circuit converts a low-voltage PWM signal to an amplified and buffered linear output.
The circuit works in the following manner. The base of the PNP in Q1 is the non-inverting input to the
amplifier, and the emitter of the NPN is the inverting input. The PNP is biased as an emitter follower, and the
NPN is used both as an emitter follower and as the initial gain element. As the PNP and the NPN operate at
roughly the same current density and temperature, the two input voltages approximately track each other. Any
current which flows out of the inverting input is mirrored to the NPN collector, causing a drop across resistor
R2. The drop across R2 drives the V
GS
of Q2, which is amplified at Q2's drain, the amplifier output. The
Page 1 of 3
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
