I am usiing LMR64010 to convert 5V to 12V. Load current is approx 150ma. Th e schematic is as per the application circuit in the datasheet. If I pull t he shutdown pin to ground the o/p is approx 4.6V. Looking at the circuit th ere is an i/p to o/p path through the inductor and diode giving me 5V minus diode drop during shut down.
Is it normal for boost converters? is there a simple way to make the o/p to 0V if the regulator is in shutdown mode?
-bhavj
On a sunny day (Wed, 6 Nov 2013 03:59:18 -0800 (PST)) it happened snipped-for-privacy@gmail.com wrote in :
Yes.
Power MOSFET in series with input or output?
Use SEPIC instead.
Tim
-- Seven Transistor Labs Electrical Engineering Consultation Website:
Is it normal for boost converters? is there a simple way to make the o/p to 0V if the regulator is in shutdown mode?
-bhavj
Here's a boost-doubler circuit. It adds C6 and D1 to the usual boost converter. I wanted to pre-charge the output cap, so I have R14; you'd probably want to delete that.
This is in production, boosting 9 volts to 48 in a tiny laser driver. Works fine.
-- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
I have done that, it works well in practice. You lose a bit of efficiency, but it's a worthwhile price to pay if you want "off" to really be "off".
-- Tim Wescott Wescott Design Services http://www.wescottdesign.com
This is a cheap fix: Please view in a fixed-width font such as Courier.
. . . . .------------------------------------------. . | | . | G . | SD . 5V---+----+-------LLLLL-------+--|>|---+-------+---S D--> . | | | | | . | | ------------ | | | Si2347DS . | | | | | | | P-CH MOSFET . +| +---|Vin SW|--' | +| . === | | | | === . | [51K] | LMR64010 | | | . | | | | ------- | . | | |____ | | FDBK | | . >--------+---|SHDN FB|-------| | | . | | | | DVDR | | . | | GND | ------- | . | ------------ | | . | | | | . ----+---------------+-----------------+-------+---------- . | . --- . /// . . . . - OR - . . 1n . .-------------------------------+--||-. . | | | . | G --- . | SD /// . 5V---+----+-------LLLLL-------+--|>|----S D----+-------+-> . | | | | | . | | ------------ | Si2347DS | | . | | | | | P-CH MOSFET | | . +| +---|Vin SW|--' | +| . === | | | | === . | [51K] | LMR64010 | | | . | | | | ------- | . | | |____ | | FDBK | | . >--------+---|SHDN FB|-----------------| | | . | | | | DVDR | | . | | GND | ------- | . | ------------ | | . | | | | . ----+---------------+---------------------------+-------+- . | . --- . /// . .
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