150Vin buck converter idles at 9µA
- Autore:Ella Cai
- Rilasciare il:2018-07-25
Analog Devices has introduced a 150V buck converter that draws 9µA quiescent – that is only 1.35mW wasted at full input voltage.
Called LTC3894, its input range is 4.5 to 150V, and the the firm makes an interesting point: that this wide range can eliminate the need for external surge suppression devices on lower voltage rails.
The chip works with an external p-channel mosfet to produce its output, which can be anywhere between 800mV and 60V.
As it can operate at 100% duty-cycle, it can run continuously in drop-out to squeeze more from a battery, and there is an externally-adjustable ‘power good’ window detector and output signal to warn following circuitry that the battery is almost done in.
Output currents up to 3A are possible, and efficiency can be as high as 92%.
LTC3894-external-n-mosfetFor sustained high-voltage high-power (high gate capacitance) applications, where the internal regulator for the main switch gate driver will be dissipating a lot of heat, there is also an option to add an external n-channel mosfet to drop some of the voltage and share the dissipation (see diagram).
Fixed-frequency operation is selectable across 50kHz to 850kHz, or switching can be synchronised to an external clock from 75kHz to 800kHz.
Minimum on-time is 100ns, allowing high step-down ratios at high switching frequency.
Pulse-skipping and burst-mode operation is available for light loads.
Overall, this is a current-mode controller, with output current sensing either the output inductor or an external resistor.
Protection features include: current foldback (output over-current), adjustable input over-voltage lock-out, soft-start and output over-voltage.
Applications are foreseen in transportation, always-on power, industrial control, robotics and datacoms.
Versions are available to span –40°C to 125°C operation and it comes in a 16-pin thermally-enhanced TSSOP with high-voltage pin spacing.
Called LTC3894, its input range is 4.5 to 150V, and the the firm makes an interesting point: that this wide range can eliminate the need for external surge suppression devices on lower voltage rails.
The chip works with an external p-channel mosfet to produce its output, which can be anywhere between 800mV and 60V.
As it can operate at 100% duty-cycle, it can run continuously in drop-out to squeeze more from a battery, and there is an externally-adjustable ‘power good’ window detector and output signal to warn following circuitry that the battery is almost done in.
Output currents up to 3A are possible, and efficiency can be as high as 92%.
LTC3894-external-n-mosfetFor sustained high-voltage high-power (high gate capacitance) applications, where the internal regulator for the main switch gate driver will be dissipating a lot of heat, there is also an option to add an external n-channel mosfet to drop some of the voltage and share the dissipation (see diagram).
Fixed-frequency operation is selectable across 50kHz to 850kHz, or switching can be synchronised to an external clock from 75kHz to 800kHz.
Minimum on-time is 100ns, allowing high step-down ratios at high switching frequency.
Pulse-skipping and burst-mode operation is available for light loads.
Overall, this is a current-mode controller, with output current sensing either the output inductor or an external resistor.
Protection features include: current foldback (output over-current), adjustable input over-voltage lock-out, soft-start and output over-voltage.
Applications are foreseen in transportation, always-on power, industrial control, robotics and datacoms.
Versions are available to span –40°C to 125°C operation and it comes in a 16-pin thermally-enhanced TSSOP with high-voltage pin spacing.
