Circuit Description - ViewSonic VLCDS25973-2W Service Manual

4. Circuit Description

Circuit Description
1. Power supply (DC/DC Converter)
The AP1501 is monolithic IC designed for M/B DC/DC converter, and owns the ability of driving a 3A load without
any additional transistor component.
The AP1501 operates at a switching frequency of 150KHz and thus allows smaller-sized filter components than what
would be needed with lower frequency switch regulator.
2. Flash Memory
The Pm39LV020R is a 2 Megabit, 3.3 Volt-only Flash Memory organized as 262,144 bytes of 8 bits each. This device
is designed to use a 3.0 Volt to 3.6 Volt power supply to perform in-system programming.
The 2 Megabit memory array is divided into uniform 4Kbyte sector or uniform 64Kbyte blocks for data and/or code
storage.
The block architecture allows users to flexibly make chip erase or block erase operation. The block erase feature allows
a particular block to be erased and reprogrammed without affecting the data in other blocks. After the device performs
chip erase or block erase operation, it can be reprogrammed on a byte-by-byte basis.
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