Product category: Power Supply ICs and Controllers
News Release from: National Semiconductor | Subject: LM5642
Edited by the Electronicstalk Editorial Team on 17 June 2003
Wide input range for flexible switching
controller
The LM5642 is a high-voltage two-phase synchronous switching controller tailored for power supply designs for communications, industrial and automotive applications.
The LM5642 is a high-voltage, two-phase synchronous switching controller tailored for power supply designs for communications, industrial and automotive applications Its wide input voltage range (4.5 to 36V) makes the feature-rich device a low-cost, point-of-load (POL) regulator solution for distributed power architectures (DPAs)
This article was originally published on Electronicstalk on 5 Jan 2001 at 8.00am (UK)
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National Semiconductor's LM5642 is flexible, operating in two modes, providing two outputs, or in biphase mode for a single output with twice the load current.
The current-mode control loop can use either a discrete current sense resistor or top-side N-channel mosfet on-resistance sensing, over a broad conversion range, for example 36V in and 1.8V out.
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"The digital ASIC and DSP content of the systems powered by DPAs is increasing, so is the number of low voltages required at the point of load", said Werner Berns, Marketing Manager of National Semiconductor's power management group in Europe.
"A dual regulator is particularly useful in this environment.
Smart sequencing is also essential as the number of rails increases to prevent latch-up and misoperation of complex loads.
The LM5642 has the built-in flexibility to meet emerging requirements".
Enabling high conversion ratios with up to 95% efficiency, National's LM5642 controller is ideal for any of the new DPAs with bus voltages such as 5, 12, 24 and up to 36V.
It also can be combined with National's recently announced 100V push-pull controller (LM5030) to provide secondary post-regulation in multiple output isolated DC/DC power modules.
The LM5642 oscillator frequency can be synchronised up or down between 150 and 250kHz, allowing users to mitigate switching frequency interference.
It can run at 200kHz where two controllers operate 180 degrees out of phase, significantly reducing the input filter capacitance in high current applications where the device is used as a single-output regulator.
Each output of the LM5642 can be set from 1.3 to 13.5V.
Current-mode control with or without a current-sense resistor ensures superior line and load regulation over a wide input voltage range.
The combination of independent channel enable and soft-start pins makes power sequencing easy.
Wide loop bandwidth results in fast response to load transients and rejection of line transients.
These features, and more others, make the LM5642 perfectly suited for projects that need multiple, efficient supplies.
National Semiconductor's LM5642 dual synchronous switching controller in a TSSOP-28 package is available today.
It is priced at $1.85 each in 1000 units.
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