When designing a PCB, selecting between DC/DC converters or LDOs for power supply chip design is essential.
A. Simply put, in boost scenarios, only DC/DC can be utilized, as LDOs are linear regulators that can’t increase voltage.
When the designed circuit has the following requirements for the shunt power supply:
1. Excellent noise and ripple suppression;
2. Minimal PCB area, such as in mobile phones and other portable electronic devices;
3. Inductors are not permitted for circuit power supply, as in the case of mobile phones;
4. The power supply must feature instantaneous calibration and self-checking of the output state.
5. The voltage regulator should have a low voltage drop and low power consumption.
6. A low-cost design with a straightforward scheme is essential.
In this context, LDO emerges as the ideal choice while simultaneously meeting various product design requirements.
Secondly, let’s explore the main characteristics of each:
DC/DC: high efficiency, high noise; it excels in conversion efficiency and can handle large currents, but generates significant output interference and is bulkier in size.
LDO: low noise, low static current; it is compact with minimal interference, though it exhibits low conversion efficiency when there’s a substantial input-output voltage difference.
Thus, for applications with a relatively large voltage drop, DC/DC is preferable due to its high efficiency, while LDO suffers from efficiency losses under significant voltage drops.
Conversely, when the voltage drop is minor, LDO is favored for its low noise, clean power supply, simple peripheral circuitry, and cost-effectiveness.
LDO, or Low Dropout regulator, signifies a low-voltage differential linear regulator, distinguishing it from traditional linear regulators. Traditional linear voltage regulators, like the 78XX series, require an input voltage that exceeds the output voltage by 2V to 3V to function properly. However, in scenarios like converting 5V to 3.3V, where the voltage differential is only 1.7V, this condition is too stringent. Hence, LDO power conversion chips are utilized.
The principle of LDO linear step-down chips is akin to resistor voltage division to achieve voltage reduction, resulting in significant energy loss as the reduced voltage dissipates as heat. The larger the voltage drop and load current, the more pronounced the heating effect. Consequently, these chips tend to have larger packages, which facilitates heat dissipation.
Examples of LDO linear buck chips include: 2596 and L78 series.
In contrast, DC/DC buck chips experience minimal energy loss during the bucking process, resulting in less noticeable heating. They typically have smaller packages and can implement PWM digital control.
Examples of DC/DC step-down chips are TPS5430/31, TPS75003, MAX1599/61, and TPS61040/41.
In general, when designing PCBs, a DC/DC converter should be selected for voltage boosting, while either DC/DC or LDO can be chosen for bucking voltage. It’s crucial to compare cost, efficiency, noise, and performance, focusing on application-specific analysis.
A. Simply put, in boost scenarios, only DC/DC can be utilized, as LDOs are linear regulators that can’t increase voltage.
When the designed circuit has the following requirements for the shunt power supply:
1. Excellent noise and ripple suppression;
2. Minimal PCB area, such as in mobile phones and other portable electronic devices;
3. Inductors are not permitted for circuit power supply, as in the case of mobile phones;
4. The power supply must feature instantaneous calibration and self-checking of the output state.
5. The voltage regulator should have a low voltage drop and low power consumption.
6. A low-cost design with a straightforward scheme is essential.
In this context, LDO emerges as the ideal choice while simultaneously meeting various product design requirements.
Secondly, let’s explore the main characteristics of each:
DC/DC: high efficiency, high noise; it excels in conversion efficiency and can handle large currents, but generates significant output interference and is bulkier in size.
LDO: low noise, low static current; it is compact with minimal interference, though it exhibits low conversion efficiency when there’s a substantial input-output voltage difference.
Thus, for applications with a relatively large voltage drop, DC/DC is preferable due to its high efficiency, while LDO suffers from efficiency losses under significant voltage drops.
Conversely, when the voltage drop is minor, LDO is favored for its low noise, clean power supply, simple peripheral circuitry, and cost-effectiveness.
LDO, or Low Dropout regulator, signifies a low-voltage differential linear regulator, distinguishing it from traditional linear regulators. Traditional linear voltage regulators, like the 78XX series, require an input voltage that exceeds the output voltage by 2V to 3V to function properly. However, in scenarios like converting 5V to 3.3V, where the voltage differential is only 1.7V, this condition is too stringent. Hence, LDO power conversion chips are utilized.
The principle of LDO linear step-down chips is akin to resistor voltage division to achieve voltage reduction, resulting in significant energy loss as the reduced voltage dissipates as heat. The larger the voltage drop and load current, the more pronounced the heating effect. Consequently, these chips tend to have larger packages, which facilitates heat dissipation.
Examples of LDO linear buck chips include: 2596 and L78 series.
In contrast, DC/DC buck chips experience minimal energy loss during the bucking process, resulting in less noticeable heating. They typically have smaller packages and can implement PWM digital control.
Examples of DC/DC step-down chips are TPS5430/31, TPS75003, MAX1599/61, and TPS61040/41.
In general, when designing PCBs, a DC/DC converter should be selected for voltage boosting, while either DC/DC or LDO can be chosen for bucking voltage. It’s crucial to compare cost, efficiency, noise, and performance, focusing on application-specific analysis.
