sd card voltage level converter

Markdem · Joined: 24 Jun 2005 Posts: 206

Hi All, really quick one, can I use a 4050 hex buffer for level conversion for a SD car interface? I have checked the timing values, and they look OK. I just want to make sure.

Thanks, Mark

mkent · Joined: 09 Sep 2003 Posts: 37 Location: TN, USA

Look at the min high input for a 5v VCC. It looks marginal to me. TI and others have announced some new chips designed for level conversions and they may be a safer choice. Also look at the 74CX125 and 74HC125 paying close attention to the switching voltage specs.

libor · Joined: 14 Dec 2004 Posts: 288 Location: Hungary

you can go safely down to 4.2 Vcc with a 'normal 5V' PIC according to the datasheets, this alone will give you some more safety margin in the level detection. use a simple diode drop for lowering the PIC's Vcc if you already have a 5V psu.