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Switching a low voltage to a load

Poor voltage drop. ...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142     Skype: skypeanalog  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.
Reply to
Jim Thompson
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All you need for a -ve rail is a small cap + diode connected to any node that switches. However this generally does mean the -ve rail doesn't go -ve until after Vcc is applied.

NT

Reply to
tabbypurr

That's a mistake. Any substantial load should always be switched in/out at one of your power supply rails, because those allow easy biasing decisions: a 3.3V high-side switch is easy. A 0.0V low-side switch is easy. A 1.2V switch requires the ground current to get the same 0.25A modulation as a ground-side switch, but it's harder to bias a MOSFET to do it.

Reply to
whit3rd

Should be less than 100mV, using jellybean (~BC807). Thats equivalent to a 400mR fet, without looking.

RL

Reply to
legg

The OP, IIRC, said 0.5 AMP. ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142     Skype: skypeanalog  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.
Reply to
Jim Thompson

See above - 0.25A

RL

Reply to
legg

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