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For a battery powered circuit, I need a VERY low quiescent current voltage regulator. Input voltage is 20V lithium battery, output voltage is 5V (or 3.3V, precision not necessary) for a microcontroller circuit. The max current, when uC is working, should be at least 50 mA. The quiescent current of the regulator itself (when uC is in sleep mode) should be no more than 10uA. On the battery terminals, there are transients of 40V to be expected. Any ideas? No automotive application, but sort of power tool. The uC, when in "sleep mode", waits for "years" until it detects a "keypressed" by the user, before starting the engine. The whole appliance is very cost sensitive, so the regulator should be in a price range of 0.1..0.2 USD @ 10K pa. If anyone has a cheap 20uA solution: welcome.

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  • \$\begingroup\$ More details are required, is it an automotive application? Can you use DC2DC converter with bypass mode? Can you enable/disable the LDO? \$\endgroup\$ – Lior Bilia Nov 2 '14 at 13:28
  • \$\begingroup\$ wow, you should really use a DC-DC converter, and put a TVS diode to clamp the 40V transients too \$\endgroup\$ – KyranF Nov 2 '14 at 13:43
  • \$\begingroup\$ 20uA is easier, and would not much affect the self-discharge of 3600mAh battery. \$\endgroup\$ – Spehro Pefhany Nov 2 '14 at 13:44
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The TPS7A6601 has 12uA typical (20uA max) Iq, and can withstand 45V for 200ms. Pretty close.

Or make a high dropout/high voltage linear pre-regulator using a MOSFET voltage follower and one of the many low-Iq LDO CMOS regulators that can't handle high input voltage.

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    \$\begingroup\$ Preregulator is a good idea. Let's focus on circuit techniques, in order to keep this from becoming a shopping question. \$\endgroup\$ – Dave Tweed Nov 2 '14 at 14:48
  • \$\begingroup\$ Preregulator, You mean a 10V ZenerDiode with a series resistor ( 5 Meg ) and I feed this Voltage to a N-CH Gate . Then the (low iq) LDO is supplied from the N-CH source? \$\endgroup\$ – jgr Nov 2 '14 at 14:55
  • \$\begingroup\$ Yes, something along those lines ~3 green LEDs in series might make a better Zener than a Zener diode. \$\endgroup\$ – Spehro Pefhany Nov 2 '14 at 16:03

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