是个中年

写真付きで日記但是不管是在や趣味を書くならgooブログ

Emitter follower Q3 drives the bases of Q1 and Q2

2017-06-30 12:01:42 | 日記
Emitter follower Q3 drives the bases of Q1 and Q2, which mirror the 17 mA of D1.

This article is come from:http://www. In normal dc/dc-converter applications, the control circuitry uses a power stage comprising an inductor and a capacitor, along with feedback through a resistor-divider network, to generate a regulated constant voltage and thus a constant current through the resistor divider.8V across R1. The VBE drops of emitter followers Q1 and Q2 are similar to and compensate for the VBE drop of Q3, so the voltage across R5 and R6 is also a constant 0. R4 should be set so that the voltage across C3 can support the highest LED voltage plus approximately 255 mV to keep Q1 and Q2 from saturating.8V reference voltage divided by R1. The voltage across C3 will be edison lamp regulated to whatever voltage is required to support the voltage across D1 and R4, as well as the 0. The first LED channel for D1 is driven by a regulated current of 17 mA, which is equal to the IC’s 0.mosopower.net is provided with independent import and export entitlements, and is provided with professional, concentrative and dedicated pioneering spirits, devotes to the development, design, production and sale of various switching power supplies, adapters, chargers, high / low frequency transformers, etc.

Tips for Converting

You can use an LED in place of the upper resistor of the feedback-divider network to allow the constant current driver to be driven with a constant regulated current.8V, and D2 and D3 are driven with a constant 17 mA.R4 is set so that the voltage across C3 is high enough such Air Compressor for the Car that Q1 and Q2 do not saturate. As a result, only one LED channel would be lighted.storage-battery. Although this method works well with one LED channel, it cannot be used to drive multiple parallel LED channels, because the mismatch in LED voltage drops would cause one LED channel to consume most of the current.

www. The IC used in the figure is the TN1000, a 100-mA current-mode step-down dc/dc converter from Technor Semiconductor.
About LED Driver

With only a few additional components, you can use a highly efficient step-down dc/dc converter to create a constant-current, multiple-channel led current driver. The current flowing through the LED will be equal to the reference voltage of the dc/dc converter divided by the resistance of the grounded bottom resistor.htm


.com/index. It is relatively easy to drive a single-channel LED; however, it becomes more complicated when driving multiple-channel paralleled LEDs.php/3-channel-white-led-driver-uses-step-down-dc-to-dc-converter.

Steps for Converting

His voltage step-down stage consists of a 12-H inductor and a 22-F capacitor. You can use the circuit in Figure 1 to drive multiple paralleled LED channels with only one dc/dc converter by adding a simple current-mirror scheme to generate the constant current required for each LED channel.
ジャンル:
ウェブログ
コメント   この記事についてブログを書く
この記事をはてなブックマークに追加
« Such websites comprise of c... | トップ | So, you do not need to repl... »

コメントを投稿


コメント利用規約に同意の上コメント投稿を行ってください。

数字4桁を入力し、投稿ボタンを押してください。

あわせて読む

トラックバック

この記事のトラックバック  Ping-URL
  • 30日以上前の記事に対するトラックバックは受け取らないよう設定されております。
  • 送信元の記事内容が半角英数のみのトラックバックは受け取らないよう設定されております。
  • このブログへのリンクがない記事からのトラックバックは受け取らないよう設定されております。
  • ※ブログ管理者のみ、編集画面で設定の変更が可能です。