Multiple Voltage Regulator with Switch and Ignition Buffer

The TDA3681A is a multiple output voltage regulator with a power switch and an ignition buffer. It is intended for use in car radios with or without a microcontroller. The TDA3681A contains the following:

• Four fixed voltage regulators with a foldback current protection (regulators 1, 2, 3 and 4). Regulator 2, which is intended to supply a microcontroller, also operates during load dump and thermal shutdown
• Regulators 3 and 4 have a second supply pin that can be connected to a lower supply voltage (> 6.5 V) to reduce the power dissipation
• A power switch with protection, operated by a control input
• Reset and hold outputs that can be used to interface with the microcontroller; the reset signal can be used to call up the microcontroller
• Both supply pins can withstand load dump pulses and negative supply voltages
• Regulator 2, which is in regulation at a backup voltage above 6.5 V
• A provision for the use of a reserve supply capacitor that will hold enough energy for regulator 2 (5 V continuous) to allow a microcontroller to prepare for loss of voltage
• An ignition input Schmitt trigger with push-pull output stage.