General Description
EM78P157N is an 8-bit microprocessor designed and developed with low-power, high-speed CMOS technology. It is equipped with 1K*13-bits Electrical One Time Programmable Read Only Memory (OTP-ROM). It provides three PROTECTION bits to prevent user’s code in the OTP memory from being intruded. Eight OPTION bits are also provided to meet user’s additional requirements.

Features
● Operating voltage range: 2.5V~5.5V
● Operating temperature range: -40°C~85°C
● Operating frequency range (base on 2 clocks ):
      • Crystal mode: DC~20MHz at 5V, DC~8MHz at 3V, DC~4MHz at 2.5V.
      • ERC mode: DC~4MHz at 5V, DC~4MHz at 3V, DC~4MHz at 2.5V.
● Low power consumption:
      • Less then 2 mA at 5V/4MHz
      • Typically 20 µA at 3V/32KHz
      • Typically 1 µA during sleep mode
● 1K × 13 bits on chip ROM
● One security register to prevent intrusion of OTP memory codes
● One configuration register to accommodate user’s requirements
● 48× 8 bits on chip registers (SRAM, general purpose register)
● 2 bi-directional I/O ports
● 5 level stacks for subroutine nesting
● 8-bit real time clock/counter (TCC) with selective signal sources, trigger edges, and overflow interrupt
● Two clocks per instruction cycle
● Power down (SLEEP) mode
● Three available interruptions
      • TCC overflow interrupt
      • Input-port status changed interrupt (wake up from sleep mode)
      • External interrupt
● Programmable free running watchdog timer
● 8 programmable pull-high pins
● 7 programmable pull-down pins
● 8 programmable open-drain pins
● 2 programmable R-option pins
● Package types:
      • 14 pin DIP 300mil : EM78P157NBP
      • 14 pin SOP 150mil : EM78P157NBM
      • 18 pin DIP 300mil : EM78P157NAP
      • 18 pin SOP 300mil : EM78P157NAM
      • 20 pin SSOP 209mil : EM78P157NAAS
      • 20 pin SSOP 209mil : EM78P157NAKM
● 99.9% single instruction cycle commands
● The transient point of system frequency between HXT and LXT is around 400KHz