AFL50XXS Series
Block Diagram
Figure I. AFL Single Output
Input
Filter
1
4
5
+ Input
Output
Filter
+Output
+Sense
7
Primary
Bias Supply
Enable 1
10
Current
Sense
Sync Output
Share
Amplifier
11 Share
Control
Error
Amp
& Ref
Sync Input
Case
6
3
Enable 2
FB
12
Sense
Amplifier
9
8
Return Sense
Output Return
Input Return
2
of application. When the remote sensing feature is not used,
the sense lead should be connected to their respective
output terminals at the converter. Figure III. illustrates a
typical remotely sensed application.
Circuit Operation and Application Information
The AFL series of converters employ a forward switched
mode converter topology. (refer to Figure I.) Operation of
the device is initiated when a DC voltage whose magnitude
is within the specified input limits is applied between pins 1
and 2. If pin 4 is enabled (at a logical 1 or open) the primary
bias supply will begin generating a regulated housekeeping
voltage bringing the circuitry on the primary side of the
converter to life. A power MOSFET is used to chop the DC
input voltage into a high frequency square wave, applying
this chopped voltage to the power transformer at the nominal
converter switching frequency. Maintaining a DC voltage
within the specified operating range at the input assures
continuous generation of the primary bias voltage.
Inhibiting Converter Output (Enable)
As an alternative to application and removal of the DC voltage
to the input, the user can control the converter output by
providing TTL compatible, positive logic signals to either of
two enable pins (pin 4 or 12). The distinction between these
two signal ports is that enable 1 (pin 4) is referenced to the
input return (pin 2) while enable 2 (pin 12) is referenced to
the output return (pin 8). Thus, the user has access to an
inhibit function on either side of the isolation barrier. Each
port is internally pulled “high” so that when not used, an
open connection on both enable pins permits normal
converter operation. When their use is desired, a logical
“low” on either port will shut the converter down.
The switched voltage impressed on the secondary output
transformer winding is rectified and filtered to generate the
converter DC output voltage. An error amplifier on the
secondary side compares the output voltage to a precision
reference and generates an error signal proportional to the
difference. This error signal is magnetically coupled through
the feedback transformer into the controller section of the
converter varying the pulse width of the square wave signal
driving the MOSFET, narrowing the width if the output voltage
is too high and widening it if it is too low, thereby regulating
the output voltage.
Figure II. Enable Input Equivalent Circuit
+5.6 V
100K
1N4148
Pin 4 or
Pin 12
290K
180K
Disable
Remote Sensing
2N3904
Connection of the + and - sense leads at a remotely located
load permits compensation for excessive resistance
between the converter output and the load when their
physical separation could cause undesirable voltage drop.
This connection allows regulation to the placard voltage at
Pin 2 or
Pin 8
www.irf.com
5
5秒后页面跳转
VIPER22A的资料手册解读、引脚参数说明、代换型号推荐
ADS1256的资料手册解读、采集电压范围、读数变化原因分析及实际测量遇到的问题
MAX6675资料手册参数详解、引脚配置说明
LM258引脚图及功能介绍、主要参数分析
微信公众号
抖音公众号
浙公网安备 33010502006866号 浙ICP备10014259号-119
营业执照ICP证
数据手册
如果您发现信息不准确，
