**1. Open Collector (OC) Output:**
The structure of an open collector output is shown in Figure 1. As the name suggests, the collector of the transistor on the right side is not connected to any voltage source, hence it is referred to as "open collector." The left transistor acts as an inverter: when the input is "0," the output is also "0."
In Figure 1, when the input at the left end is "0," the front transistor turns off, meaning the collector and emitter are disconnected. This allows 5V from the power supply to flow through a 1kΩ resistor to the right transistor, turning it on (acting like a closed switch). However, when the input is "1," the front transistor turns on, cutting off the current to the right transistor, which then turns off (like an open switch).
To simplify, Figure 2 shows a software-controlled switch: "1" means the switch is open, and "0" means it's closed. When the switch is closed, the output is grounded, resulting in a low level. When it's open, the output is in a high-impedance state, meaning the voltage level is undefined. If a resistive load (even a small one) is connected to ground, it can pull the output low, so this configuration cannot produce a stable high level on its own.
Looking at Figure 3, the 1kΩ resistor is a pull-up resistor. When the switch is closed, current flows through both the resistor and the switch, but since the switch has very low resistance, the voltage across it is nearly zero, resulting in a low output. When the switch is open, no current flows, so the resistor doesn't drop any voltage, allowing the output to rise to 5V—producing a high level.
However, the internal resistance of the output is relatively high (1kΩ), and if a load with resistance R is connected, the output voltage will be 5R/(R + 1000) volts. To maintain a sufficient high level, R must not be too small. If the load is too light, the output voltage may drop below the required threshold. In such cases, reducing the pull-up resistor value can increase drive capability. But the resistor can't be too small, as it could cause excessive current when the switch is closed, potentially damaging the circuit or exceeding the switch’s current rating. Therefore, selecting the right pull-up resistor involves balancing current requirements and voltage levels.
**2. Open Drain Output**
An open drain output is similar to an open collector, but instead of a bipolar junction transistor (BJT), it uses a field-effect transistor (FET) or metal-oxide-semiconductor (MOSFET). The gate of the FET is connected to the output, the source is connected to ground, and the drain is left floating, hence the term "open drain." To make it function properly, an external pull-up resistor must be connected between the drain and the power supply. This resistor is essential for pulling the output high when the FET is off.
As shown in Figure 4, open drain outputs require an external pull-up resistor to ensure proper operation. Many ICs use open drain outputs, and without the correct pull-up resistor, the circuit may not work as intended.
The principle behind open drain is similar to that of open collector, except the transistor is replaced by an FET. Instead of a collector, we now have a drain, and the term "open collector" becomes "open drain." The functionality remains largely the same: the output can only sink current, not source it. A pull-up resistor is necessary to provide a high logic level when the FET is in the off state.
In summary, both open collector and open drain outputs are designed to allow multiple devices to share a common signal line, often used in bus systems where only one device should drive the line at a time. They rely on external components like pull-up resistors to complete the circuit and ensure reliable signal transmission.
Tier 1 Solar Panel
Chinese Tier 1 brand Solar Panel (Longi, Jinko, Trina, Canadian, Ja etc.)
This type of product is mainly Tier 1 solar module product in China, include Longi solar panel. Jinko solar panel, Canadian Solar panel, ja solar panel etc.all of which are among the top 10 world-renowned brands. The original A grade product is mainly mono crystalline and half cut cell solar modules, with a power range of 400watts to a maximum of 700watts.quality warranty is 25 years.
A grade, this type of film is characterized by a neat and uniform appearance, printed electrode grid lines, no broken grid, no surface stains, no leakage, no aluminum package, no hidden cracks, no scratches, no black core, no reverse current, stable electrical performance, and high conversion efficiency
Using solar cell testing equipment to measure and screen, the conversion efficiency, filling factor, and appearance that meet certain standards are first level. Generally, the conversion efficiency, filling factor, and appearance of first level are better than those of level B
The level of solar panels can be divided into first level, second level, third level, and fourth level, and the first level components can be divided into first level+and first level - two levels. The second level is also the same, and the cost difference between different levels of solar panels is also very large.
Chinese tier 1 brand solar panel
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TIER 1 brand include
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Longi, Jinko, Trina, JA, Canadian, znshine, etc.
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quality warranty
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25 years
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grade
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original A grade (each solar panel can be checked on official website with barcode)
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power range
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400watt to max 700watt
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Tier 1 Solar Panel,Mono Solar Panel N Type,Solar Panels Bifacial 555 Watt,Solar Panel Mono Topcon Cell
PLIER(Suzhou) Photovoltaic Technology Co., Ltd. , https://www.pliersolar.com