Low dropout voltage regulators (LDOs) are common in many applications. State of the art Power-Management Integrated Circuits (PMICs) for smartphones and other portable devices include over a dozen LDOs. LDOs are also found integrated onto Microprocessors, Graphics Processing Units (GPUs), and in many other Systems on a Chip (SOCs).
LDOs come in many different shapes and sizes and there is no standard one-size-fits-all option. To know which LDO you need, you must first define the application of your LDO and then determine several required specifications. To help you get started, we’ve compiled a list of 5 basic questions you should know the answer to when you begin your search for the right LDO.
1. What is your required input voltage range?
The input voltage range determines the maximum and minimum allowable input supply for the LDO. Your IP provider needs to know the full range of possible voltages that will be supplied at the input to the LDO IP block because input supplies that are higher than the maximum allowable input can damage the LDO. Based on your choice of process and available devices, input voltage range also plays a larger role in other critical specifications of the IP block such as area and current consumption.
2. What is your required output voltage?
The output voltage of an LDO may be fixed or programmable. Your IP provider will need to know the specific voltage and accuracy that is required from the LDO IP block (for example 1.2 V +/- 3%). If your application requires more than one output voltage that is selectable or programmable, your IP provider will need to know the range and output voltage step size required.
3. What is your required output current?
This parameter is the output current that the LDO can provide while meeting the other required parameters. Your IP provider may ask you to provide both the typical DC load current (for example 100 mA) as well as any peak DC current requirements. If possible at this stage, it would also be very helpful to know the transient load requirements (for example transients from 100 mA to 150 mA in 1 µs).
4. What Is Your Required Efficiency Parameter?
Power efficiency is defined as the percentage of the input power that is delivered to the output. In order to maximize the LDO efficiency we must minimize the output voltage to input voltage difference and the quiescent current of the LDO. Because efficiency is affected by these other important parameters, it’s critical to know early on what kind of efficiency you’re expecting to achieve. If you require extremely high efficiency, your IP provider may even suggest using a switching regulator instead of an LDO.
5. What are your overall priorities?
There are many other parameters and features that may be important to you, like low quiescent power consumption, low noise, over temperature protection, over voltage protection, power-on-reset, brownout detection and more. The earlier you can let your IP provider know that you require these, the easier it will be for them to point you to the right option for you or suggest a different combination of IP blocks that may better suit your needs. At Vidatronic, we have a full suite of LDOs, switching converters, and other IP blocks as part of our FlexGUARD™ Platform IP Portfolio.
To learn more about LDOs and the parameters and features available, check out our full white paper on how to choose the best LDO for your application: