IC697CPX772工控模塊系統(tǒng)備件
該架構(gòu)使用相同
NFB引腳調(diào)節(jié)為–2.48V，而放大器輸出內(nèi)部驅(qū)動FB引腳至1.245V。該架構(gòu)使用相同的主誤差放大器，防止了功能重復(fù)，并保持了易用性。請咨詢LTC市場部，了解可調(diào)節(jié)至-1.25V的裝置。放大器輸出端產(chǎn)生的誤差信號從外部輸出。該引腳（VC）具有三種不同的功能。用于頻率補(bǔ)償、電流限制調(diào)整和軟啟動。在正常調(diào)節(jié)器操作期間，該引腳的電壓介于1V（低輸出電流）和1.9V（高輸出電流）。誤差放大器是電流輸出（gm）型，因此該電壓可以被外部箝位以降低電流限制。同樣，電容器耦合的外部箝位將提供軟啟動。如果VC引腳被拉到控制引腳閾值以下，則開關(guān)占空比變?yōu)榱?，從而將LT1370置于空閑模式。正輸出電壓設(shè)置LT1370從FB引腳到地形成1.245V參考電壓（VREF）。
電阻分壓器
通過將FB引腳連接到輸出電阻分壓器來設(shè)置輸出電壓（圖1）。FB引腳偏置電流代表一個小的誤差，對于R2值高達(dá)7k的情況，通常可以忽略不計(jì)。R2的建議值為6.19k。對于正輸出應(yīng)用，NFB引腳通常保持打開狀態(tài)。可提供正固定電壓版本（請咨詢LTC營銷部）。負(fù)輸出電壓設(shè)置LT1370從NFB引腳到地形成–2.48V參考電壓（VNFR）。通過將NFB引腳連接到輸出電阻分壓器來設(shè)置輸出電壓（圖2）。–30μA NFB引腳偏置電流（INFB）可能導(dǎo)致輸出電壓錯誤，不應(yīng)忽略。這在圖2中的公式中得到了解釋。R2的建議值為2.49k。
The schema uses the same
The NFB pin is adjusted to – 2.48V, while the amplifier output internally drives the FB pin to 1.245V. This architecture uses the same main error amplifier to prevent duplication of functions and maintain ease of use. Please consult the LTC Marketing Department for devices that can be adjusted to -1.25V. The error signal generated at the output end of the amplifier is output externally. This pin (VC) has three different functions. Used for frequency compensation, current limit adjustment and soft start. During normal regulator operation, the voltage of this pin is between 1V (low output current) and 1.9V (high output current). The error amplifier is current output (gm) type, so the voltage can be clamped externally to reduce the current limit. Similarly, external clamping of capacitor coupling will provide soft start. If the VC pin is pulled below the control pin threshold, the switch duty cycle becomes zero, thereby placing the LT1370 in idle mode. The positive output voltage setting LT1370 forms a 1.245V reference voltage (VREF) from the FB pin to the ground.
Resistance divider
Set the output voltage by connecting the FB pin to the output resistance voltage divider (Figure 1). The bias current of FB pin represents a small error, which can usually be ignored when R2 value is up to 7k. The recommended value of R2 is 6.19k. For positive output applications, the NFB pin usually remains open. Positive fixed voltage version is available (please consult LTC Marketing Department). The negative output voltage setting LT1370 forms – 2.48V reference voltage (VNFR) from NFB pin to ground. Set the output voltage by connecting the NFB pin to the output resistance divider (Figure 2). – 30 μ A NFB pin bias current (INFB) may cause output voltage errors and should not be ignored. This is explained in the formula in Figure 2. The recommended value of R2 is 2.49k.
