Microchip Technology

LPC47N237 is a 3.3V (5V Tolerant) PC99a/PC2001 compliant Docking I/O controller. The device implements the LPC interface, includes I/O functionality. LPC47N237’s LPC interface supports LPC I/O and DMA cycles. There is also an SMBus hosted GPIO Block. The legacy I/O included in the LPC47N237 are: a 16C550A compatible UART; one Multi-Mode parallel port including ChiProtectTM circuitry plus EPP and ECP. The parallel port is compatible with IBM PC/ATTM architecture, as well as IEEE 1284, EPP and ECP. LPC47N237 incorporates sophisticated power control circuitry (PCC) which includes support for PME. PCC supports multiple low power-down modes. The I/O Address, DMA Channel and hardware IRQ of each logical device in the LPC47N237 may be reprogrammed through the internal configuration registers. **Family parts**LPC47N237-MT

LR12 is a high voltage, low output current, adjustable linear regulator. It has a wide operating input voltage range of 13.2 - 100V. The output voltage can be adjusted from 1.20 - 88V, provided that the input voltage is at least 12V greater than the output voltage. The output voltage can be adjusted by means of two external resistors R1 and R2 as shown in the typical application circuits. The LR12 regulates the voltage difference between VOUT and ADJ pins to a nominal value of 1.20V. The 1.20V is amplified by the external resistor ratio R1 and R2. An internal constant bias current of typically 10µA is connected to the ADJ pin. This increases VOUT by a constant voltage of 10µA times R2. The LR12 has current limiting and temperature limiting. The output current limit is 100mA maximum and the minimum temperature limit is 125°C. An output short circuit current will therefore be limited to 100mA maximum. When the junction temperature reaches its temperature limit, the output current and/or output voltage will decrease to keep the junction temperature from exceeding its temperature limit. For SMPS start-up circuit applications, the LR12 turns off when an external voltage greater than the output voltage of the LR12 is applied to VOUT of the LR12. To maintain stability, a bypass capacitor of 100nF or larger and a minimum DC output current of 500µA are required.

LR645 is a high input voltage, low output current linear regulator. It has a 3-terminal fixed output voltage version available in TO-92, TO-220 and SOT-89 packages, as well as an adjustable voltage version available in an 8-lead SOIC package. The 3-terminal version functions like any other low voltage 3-terminal regulator except it allows the use of much higher input voltages. When used in a SMPS start-up circuit, it eliminates the need for large power resistors. In this application, current is drawn from the high voltage line only during start-up. Only leakage current flows after start-up, thereby reducing the continuous power dissipation to a few milliwatts. The adjustable voltage version allows trimming of the output voltage from 8.0 to 12V. This version can also be connected to an external depletion mode MOSFET for increased output current. When used in conjunction with depletion mode MOSFET DN2540N5, an output current of up to 150mA is achieved.