Lastest News on Semiconductors

Published:2011/4/26 2:20:00 Author:Phyllis From:SeekIC

A chip that can transforme DC-DC converters to accurate charger that suitable for any rechargeable batteries has been introduced by Linear Technology Corporation recently. Named as LTC4000, this chip has the function of handling input and output voltages from 3V to 60V and also making back-up mediation between the battery, input supply and load. It can drive topologies like boost, buck, buck-boost, flyback and SEPIC for most typical DC-DC converters. In addition, it can also supply the system load with power when the input is limited and control external NFETs to protect the device from current reversing. Even when it is connected to a dead or flat battery, the chip allows the load to be power supplied by external power that ranging from mW to kW.

The programmable float voltage is 0.2%, and it has a selectable timer, or C/X current termination. It can get charged by using a thermistor under certain circumstances. The chip also featured in automatic re-charging, C/10 trickle charge for deeply discharging cells, and bad battery detecting.

The interface of the LTC4000 and DC-DC converter is related to the converter’s compensation pin, so the DC-DC converter is required to have a control or external compensation pin, called VC or ITH, whose voltage level varies with its output in a positive monotonic way. The output variable can be either output current or output voltage. There’s an amplifier inside the chip that using a discrete resistor and capacitor to compensate the combined circuit as it is connected to the compensation pin.

On Semiconductor introduced a single channel LED driver, which was known as CAT3661, using a patented architecture and fault protection and fault diagnostics for tuning power applications like portable handheld medical equipment. This driver was able to drive a single LED backlight with a current of 5mA. Features of Soft-start current limiting and short-circuit protection made the new device ideal for use in equipment powered by coin cell batteries. Typical applications include LCDs and a wide range of portable handheld device including medical equipment. Being packaged in a 16-lead TQFN, the chip’s quad-mode charge pump supports input voltages ranging from 2.0V to 5.5V and also helps achieve peak efficiency levels of up to 92 percent. The related integrated circuit is MC100ELT22D.


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