Switch 3A with a small reed switch

Hi there,
I'm wanting to switch around 3A using a reed switch (eg
http://www.dse.co.nz/cgi-bin/dse.storefront/en/product/P7856) with the
aim of driving a SSC P7 LED.
Source voltage will be be around 3.7v (Li-ion) and the max current
through the LED will be 2.8A.

Could I use this MOSFET (BUZ-71 Sipmos Power FET) to achieve this? My
understanding of electronics is basic, so if you could provide a
circuit/guidance it would be much appreciated.

Thanks in advance

 

[Jasen Betts]

On 2008-08-06, jmunrohill@gmail.com <jmunrohill@gmail.com> wrote:

Hi there,
I'm wanting to switch around 3A using a reed switch (eg
http://www.dse.co.nz/cgi-bin/dse.storefront/en/product/P7856) with the
aim of driving a SSC P7 LED.
Source voltage will be be around 3.7v (Li-ion) and the max current
through the LED will be 2.8A.

Could I use this MOSFET (BUZ-71 Sipmos Power FET) to achieve this? My
understanding of electronics is basic, so if you could provide a
circuit/guidance it would be much appreciated.

most mosfets like to have atleast 10V worth of gate drive.
The BUZ-71 may not even begin turning on until it sees 4V
(datasheeet says 3 to 4v) and suggests that 10V is needed to be fully
on.

If you've only got about 4v you may have to use a bipolar transistor
instead. eg: TIP41, (use a 100 ohm resistor on the base). but if you
can get another 6V below the Li-ion's negative terminal the BUZ71
could be made to work (9.7V will be close enough).

Bye.
Jasen