“Linear has launched a high-efficiency, 2.25MHz, synchronous step-down voltage regulator ltc3543, which can provide continuous output current up to 600mA and is packaged in 2mmx3mmdfn. The ltc3543 can operate at a constant frequency of 2.25MHz, spread spectrum or synchronous phase locked loop (PLL) mode, providing a variety of options for very low noise operation. Its current mode architecture allows operation with an input voltage of 2.5V to 5.5V, so the device is very suitable for single lithium-ion battery or multiple alkaline / NiCd / NiMH battery applications. Ltc3543 can generate output voltage as low as 0.6V and can supply power to the latest generation of low-voltage DSP and microcontroller. Its 2.25MHz switching frequency allows the use of slim, low-cost ceramic capacitors and inductors with a height of less than 1mm, which can form a very compact solution for handheld applications.

Ltc3543 adopts internal switches with RDS (on) of only 0.35 Ω (n-channel) and 0.45 Ω (p-channel), with an efficiency of up to 95%. It also operates with a low dropout duty cycle of 100%, allowing the output voltage to be equal to VIN, which further extends the battery operating time. In order to achieve maximum efficiency under light load, the ltc3543 can operate in automatic low ripple (20mvpk-pk) burst mode with no-load quiescent current of only 45ua. If the application is noise sensitive, burst mode operation can also be replaced by pulse hopping, spread spectrum or PLL (synchronized with an external clock of 1MHz to 3MHz) mode with lower noise. In all modes, the device keeps the shutdown current below 1uA, thus maximizing the battery working time. Other features of the ltc3543 include ± 2% output voltage accuracy, internal soft start and overheating protection.

Functional characteristics and application range of Synchronous Buck DC / DC converter ltc3543

Performance summary: ltc3543

600mA output current

Input voltage range from 2.5V to 5.5V

2.25MHz constant frequency, spread spectrum or synchronous PLL (1MHz to 3MHz) operation

High efficiency: up to 95%

Very low quiescent current with low ripple (20mvpk-pk) when operating in burst mode: IQ = 45ua

Low differential pressure operation: 100% duty cycle

Overheat protection

It can be stabilized with ceramic capacitors

The shutdown mode consumes only 1uA of supply current

± 2% output voltage accuracy

Current mode operation enables excellent voltage and load transient response

Flat (0.75mm) 2mmx3mm 6 lead DFN package

Z responsible editor: GT

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