I recently purchased an LCD display from All Electronics. The exact part I purchased is available at this link for your reference. The documentation which is on that same page is a very hard to read PDF. After looking it over many times and reading the documentation for other similar devices on DigiKey I have determined that I need to supply this thing with three different level's of voltage. +5V for the Logic, -22 for V_EE and -17 for V_LCD. It also says that typical I_EE is 13mA (max of 20 mA). The current for the +5V logic line is 10mA typical (20mA max).
Anyways, I've been doing a lot of searching trying to figure out how to get +5V to these vales of -22V and -17V. Or even something close. I'm thinking maybe -20V for V_EE and -15V for V_LCD.
I've looked at DC to DC voltage regulators, linear regulators, and lots of other stuff on DigiKey. I'm guessing this isn't an uncommon problem and so hopefully someone can provide some good advice for me.
For example I am looking at the LM337 and the PDF documentation makes it seem like it could be as simple as picking the right resistor's to get the right output, but I'm not sure.
Also on DigiKey I looked at the TC7660. It seems like you can cascade these to get a multiplication effect, but it says in the absolute maximum ratings section that the maximum supply voltage is +13V. Does this mean that if I start with +5V and cascade 4 of them to get -20V I will be okay, or will the -15V going into the 4th chip in the cascade be above the rating of +13V? (yes I know that -15 is less than +13, but maybe that maximum rating is an absolute value). I better stop and let you guy have at it.
Anyways, I've been doing a lot of searching trying to figure out how to get +5V to these vales of -22V and -17V. Or even something close. I'm thinking maybe -20V for V_EE and -15V for V_LCD.
I've looked at DC to DC voltage regulators, linear regulators, and lots of other stuff on DigiKey. I'm guessing this isn't an uncommon problem and so hopefully someone can provide some good advice for me.
For example I am looking at the LM337 and the PDF documentation makes it seem like it could be as simple as picking the right resistor's to get the right output, but I'm not sure.
Also on DigiKey I looked at the TC7660. It seems like you can cascade these to get a multiplication effect, but it says in the absolute maximum ratings section that the maximum supply voltage is +13V. Does this mean that if I start with +5V and cascade 4 of them to get -20V I will be okay, or will the -15V going into the 4th chip in the cascade be above the rating of +13V? (yes I know that -15 is less than +13, but maybe that maximum rating is an absolute value). I better stop and let you guy have at it.
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