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Topic: '328 + RTC + Dual Voltage LDO with Iq=1uA (Read 2114 times) previous topic - next topic


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

(* jcl *)

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


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  ;)


@Drmn4ea Thanks!

The SMD LDO is a TPS780330220DDC.

(* jcl *)

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


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 :-)

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