GENERAL DESCRIPTION
The HY29F400A is a 4 Megabit, 5 volt only CMOS Flash memory organized as 524,288 (512K) bytes or 262,144 (256K) words. The device is offered in industry-standard 44-pin PSOP and 48-pin TSOP packages.

KEY FEATURES
■ 5 Volt Read, Program, and Erase
    – Minimizes system-level power requirements
■ High Performance
    – Access times as fast as 50 ns
■ Low Power Consumption
    – 20 mA typical active read current in byte mode, 28 mA typical in word mode
    – 30 mA typical program/erase current
    – 5 µA maximum CMOS standby current
■ Compatible with JEDEC Standards
    – Package, pinout and command-set compatible with the single-supply Flash device standard
    – Provides superior inadvertent write protection
■ Sector Erase Architecture
    – Boot sector architecture with top and bottom boot block options available
    – One 16 Kbyte, two 8 Kbyte, one 32 Kbyte and seven 64 Kbyte sectors in byte mode
    – One 8 Kword, two 4 Kword, one 16 Kword and seven 32 Kword sectors in word mode
    – A command can erase any combination of sectors
    – Supports full chip erase
■ Erase Suspend/Resume
    – Temporarily suspends a sector erase operation to allow data to be read from, or programmed into, any sector not being erased
■ Sector Protection
    – Any combination of sectors may be locked to prevent program or erase operations within those sectors
■ Temporary Sector Unprotect
    – Allows changes in locked sectors (requires high voltage on RESET# pin)
■ Internal Erase Algorithm
    – Automatically erases a sector, any combination of sectors, or the entire chip
■ Internal Programming Algorithm
    – Automatically programs and verifies data at a specified address
■ Fast Program and Erase Times
    – Byte programming time: 7 µs typical
    – Sector erase time: 1.0 sec typical
    – Chip erase time: 11 sec typical
■ Data# Polling and Toggle Status Bits
    – Provide software confirmation of completion of program or erase operations
■ Ready/Busy# Output (RY/BY#)
    – Provides hardware confirmation of completion of program and erase operations
■ 100,000 Program/Erase Cycles Minimum
■ Space Efficient Packaging
    – Available in industry-standard 44-pin PSOP and 48-pin TSOP and reverse TSOP packages