Hey there! As an LDO (Low Dropout) supplier, I often get asked about the PSRR of an LDO. So, let’s dive right into it and figure out what PSRR is all about. LDO
What’s PSRR?
PSRR stands for Power Supply Rejection Ratio. It’s a super important spec when it comes to LDOs. In simple terms, PSRR tells you how well an LDO can keep its output voltage stable when there are changes in the input voltage.
You know, in real – world applications, the power supply voltage is never completely steady. There are all sorts of ripples and noise in the input voltage. These can come from things like the switching power supplies that are used to generate the input voltage, or just general electrical interference in the environment.
The PSRR of an LDO is usually expressed in decibels (dB). A higher PSRR value means that the LDO is better at rejecting the input voltage variations. For example, if an LDO has a PSRR of 60 dB at a certain frequency, it means that the output voltage will be 1000 times less affected by the input voltage variations at that frequency compared to a situation where there was no rejection at all.
Why is PSRR important?
Let’s think about some of the applications where LDOs are used. Take audio equipment, for instance. In audio systems, even the slightest amount of noise in the power supply can be heard as a hiss or distortion in the audio output. So, an LDO with a high PSRR is crucial here. It can filter out the noise from the input power supply and provide a clean and stable voltage to the audio components.
Another example is in precision measurement devices. These devices need a very stable power supply to ensure accurate measurements. If the power supply has a lot of noise and the LDO can’t reject it, the measurement results will be inaccurate. So, again, a high PSRR is essential.
How is PSRR measured?
Measuring the PSRR of an LDO isn’t too complicated, but it does require some specialized equipment. The basic idea is to apply a small – amplitude AC signal on top of the DC input voltage of the LDO. Then, you measure the corresponding AC signal at the output of the LDO.
The PSRR is then calculated as the ratio of the input AC signal amplitude to the output AC signal amplitude, and this ratio is converted to decibels. Mathematically, PSRR (dB) = 20 log (Vin_ac / Vout_ac), where Vin_ac is the amplitude of the AC signal at the input and Vout_ac is the amplitude of the AC signal at the output.
Factors that affect PSRR
There are several factors that can affect the PSRR of an LDO. One of the main factors is the frequency of the input voltage variations. Generally, the PSRR of an LDO decreases as the frequency of the input variations increases. This is because the internal circuits of the LDO have a limited bandwidth, and they can’t respond as quickly to high – frequency variations.
The load current also plays a role. As the load current increases, the PSRR of the LDO may decrease. This is because the internal resistance of the LDO and the load impedance interact in a way that can reduce the ability of the LDO to reject input voltage variations.
The output capacitance of the LDO is another important factor. A larger output capacitance can help improve the PSRR, especially at low frequencies. The capacitor acts as a reservoir, storing energy and helping to smooth out the output voltage.
Our LDOs and PSRR
At our company, we’ve put a lot of effort into designing LDOs with excellent PSRR performance. We use advanced circuit design techniques to ensure that our LDOs can reject input voltage variations over a wide range of frequencies.
For example, we’ve optimized the internal feedback loop of our LDOs. This feedback loop continuously monitors the output voltage and adjusts the internal transistors to keep the output voltage stable. By carefully designing the feedback loop, we can improve the PSRR at both low and high frequencies.
We also pay close attention to the choice of components in our LDOs. High – quality resistors, capacitors, and transistors are used to minimize internal noise and improve the overall performance of the LDO.
Comparing our LDOs with others
When you compare our LDOs with those from other suppliers, you’ll notice a significant difference in PSRR performance. Our LDOs have a higher PSRR over a wider frequency range, which means they can provide a more stable output voltage in real – world applications.
Let’s say you’re working on a project that requires a very low – noise power supply. With our LDOs, you can be confident that the output voltage will be free from the noise and ripples of the input power supply. This can lead to better performance and reliability of your end – product.
Applications of our high – PSRR LDOs
Our high – PSRR LDOs are suitable for a wide range of applications. In the consumer electronics market, they can be used in smartphones, tablets, and wearable devices. These devices require a stable power supply to ensure proper operation of the internal components.
In the automotive industry, our LDOs can be used in infotainment systems, engine control units, and other electronic systems. The automotive environment is full of electrical noise, and our high – PSRR LDOs can help provide a clean and stable power supply to these systems.
Conclusion
So, in a nutshell, PSRR is a crucial parameter for LDOs. It determines how well an LDO can reject input voltage variations and provide a stable output voltage. At our company, we’re committed to providing LDOs with excellent PSRR performance.
Fast Recovery Diode If you’re in the market for high – quality LDOs with great PSRR, we’d love to talk to you. Whether you’re working on a small – scale project or a large – scale industrial application, our LDOs can meet your needs. Reach out to us to start a conversation about your requirements and how our LDOs can fit into your design.
References
- "Design of Analog CMOS Integrated Circuits" by Behzad Razavi
- "The Art of Electronics" by Paul Horowitz and Winfield Hill
Tongke Electronic Co., Ltd
Tongke Electronic Co., Ltd. is one of the most experienced ldo manufacturers and suppliers in China, featured by quality products and low price. Please rest assured to wholesale advanced ldo made in China here from our factory. Contact us for pricelist.
Address: No.3,Chayuan Rd, Street 3, AilingKan, Dalingshan, Dongguan, Guangdong, China.
E-mail: jack@ctk-elec.com
WebSite: https://www.ctkchip.com/
