每个背板流行multisupply巴士（如VME ，VXI和PCI ）提供电源有限的输出3.3V，5V ， ±12V （ ±24V ） 。如果这些系统线卡增加3.3V或5V电源的要求，功率预算，从而可以支配的电路利用其从负载较轻的-12V源的功率。Maxim > App Notes > AUTOMOTIVE POWER-SUPPLY CIRCUITS
Keywords: 3.3V Supply Taps Power from the -12V PCI Bus Feb 07, 2000
APPLICATION NOTE 296
3.3V Supply Taps Power from the -12V PCI Bus
Additional Information:
q Quick View Data Sheet for the MAX668
q Samples and Literature Order Form
q Technical Support: Power
The backplanes of popular multisupply buses (such as VME, VXI, and PCI) each provide power-limited outputs of
3.3V, 5V, and ±12V (or ±24V). If adding line cards to these systems increases the requirements for 3.3V or 5V
power, the power budget thus can dictate that a circuit tap its power from the lightly loaded -12V source.
The figure below shows a circuit that derives 3.3V from -12V by boosting the -12V s……
