The MAX1809 is a reversible energy flow, constant-off-time, pulse-width modulated (PWM), step-down DC-DC converter. It is ideal for use in notebook and subnotebook computers that require 1.1V to 5V active
termination power supplies. This device features an internal PMOS power switch and internal synchronous rectifier for high efficiency and reduced component count. The internal 90mΩ PMOS power switch and 70mΩ NMOS synchronous-rectifier switch easily deliver continuous load currents up to 3A. The MAX1809 accurately tracks an external reference voltage, produces an adjustable output from 1.1V to VIN, and achieves efficiencies as high as 93%.
The MAX1809 uses a unique current-mode, constant-off-time, PWM control scheme that allows the output to source or sink current. This feature allows energy to return to the input power supply that otherwise would be wasted. The programmable constant-off-time architecture sets switching frequencies up to 1MHz, allowing the user to optimize performance trade-offs between efficiency, output switching noise, component size, and cost. The MAX1809 features an adjustable soft-start to limit surge currents during startup, a 100% duty-cycle mode for low-dropout operation, and a low-power shutdown mode that disables the power switches and reduces supply current below 1µA. The MAX1809 is available in a 28-pin QFN with an exposed backside pad, a 28-pin thin QFN, or a 16-pin QSOP.
Key Features
Applications/Uses
Source/Sink 3A
±1% Output Accuracy
Up to 1MHz Switching Frequency
93% Efficiency
Internal PMOS/NMOS Switches
90mΩ/70mΩOn-Resistance at VIN = 4.5V
110mΩ/80mΩ On-Resistance at VIN = 3V
1.1V to VIN Adjustable Output Voltage
3V to 5.5V Input Voltage Range
<1µA Shutdown Supply Current
Programmable Constant-Off-Time Operation
Thermal Shutdown
Adjustable Soft-Start Inrush Current Limiting
Output Short-Circuit Protection
Active Termination Buses (MAX1993)
DDR Memory Termination (MAX1993)
Key Specifications:
Switch-Mode DC-DC Power Supplies
Notes: **This pricing is BUDGETARY, for comparing similar parts. Prices are in
U.S. dollars and subject to change. Quantity pricing may vary
substantially and international prices may differ due to local
duties, taxes, fees, and exchange rates. For volume-specific prices
and delivery, please see the price and availability page
or contact an authorized distributor.
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