'328 + RTC + Dual Voltage LDO with Iq=1uA

Forum 2005-2010 (read only) Hardware Development
1

I just built up the prototype PCBs of the PICO1TRCL which featurea a
dual output voltage regulator (2.2V/3.3V), RTC + battery backup and
a prototype area. The boards can be build with an SMD regulator
(Iout=150mA) which has an Iq=1uA or a TH regulator (Iout=200mA) with
an Iq=15uA.

I hope to have the documentation and sleep mode example sketch
done by 28-Aug-2010 (in time for Maker Faire RI).

Pictures of the board and the feature list are at
http://wiblocks.luciani.org/PICO/PICO1TRCL-index.html

(* jcl *)

www: http://www.wiblocks.com
twitter: http://twitter.com/wiblocks
blog: http://luciani.org

2

@jcl,
Great looking board!

If you don't mind my asking, what is the SMD LDO regulator you're using with 900nA idle current? Any information on what it does over the 0.0 ~ 3.x+ voltage range?

I currently have Microchip's MCP1700T (3.3V) regulator spec'd for my 'Draculino' energyharvesting board. It's comparable in Iq (1.3uA) above 3.3V, but gets a little wonky if the input voltage drops below the regulator's nominal output voltage. (Yeah yeah, it's never supposed to be below that, but...) Characterizing over the 0 ~ 6V input range reveals:

Forward Iq*:
V, uA

0, 0
1.8, 10.4
2.1, 14.8
3.2, 28
3.3, 15
3.35, 1.2
4, 1.3
5, 1.3
6, 1.3

Not unacceptable, but if another part may perform better I'm for trying it out!

  • don't ask what it does in reverse bias! The pile of reversed FETs all over the power supply are there for a reason :wink:
3

@Drmn4ea Thanks!

The SMD LDO is a TPS780330220DDC.

(* jcl *)

www: http://www.wiblocks.com
twitter: http://twitter.com/wiblocks
blog: http://luciani.org

4

Thanks!

5

I just got in a TPS780330220 sample, and performed the same test. Even better! The results are as follows. Conditions: EN=Vin (enabled), FB=GND (3.3V output mode), 1uF input and output bypass caps, no load.

Forward Iq

V, uA

0, 0
0.3, 0.1
0.6, 0.1
1.1, 0.3
1.4, 0.9
1.6, 3.4
1.8, 4.5
2.3, 6.7
2.7, 6.8
3.0, 6.6
3.3, 6.3
3.4, 0.6
4.0, 0.6
5.0, 0.6
6.0, 0.6

I think we have a winner :slight_smile: