1  General Description 
EM78F668N are 8-bit microprocessor designed and developed with low-power, high-speed CMOS 
technology. They are equipped with 8K×15 bits Electrical Flash Memory, 256×8 bits in-system programmable EEPROM 
(for EM78F668N only), two comparators, three 8-bit timers, one 16-bit timer, two 10-bit PWM, 8 channels AD with 12-bit resolution, SPI, UART and I2C. With enhanced Flash-ROM features, the EM78F568N/EM78F668N series provide a convenient way of developing and 
verifying user’s programs.  Moreover, this Flash-ROM device offers the advantages of easy and effective program updates, using development and programming tools.  Users can avail of the ELAN Writer to easily program their development code. 
 
2  Features 
„  CPU configuration 
•  Supports 8K×15  bits program ROM 
•  304×8  bits on chip registers (SRAM) 
•  256  bytes in-system programmable EEPROM  
(for EM78F668N only) 
*Endurance: 1000,000 write/erase cycles 
•  More than 10 years data retention 
•  8-level stacks for subroutine nesting 
•  Less than 2 mA at 5V/4MHz 
•  Typically 20 μA, at 3V/32kHz 
•  Typically 2 μA, during sleep mode 
•  Four operation mode 
Mode  CPU 
Main 
Clock 
WDT 
Clock 
Sleep mode  Turn off  Turn off  Turn off
Idle Mode  Turn off  Turn off  Turn on
Green mode  Turn on  Turn off  Turn on
Normal mode  Turn on  Turn on  Turn on
„  I/O port configuration 
•  5 bidirectional I/O ports: P5, P6, P7, P8, P9 
•  Pin change wake-up port : P6 
•  40  Programmable pull-down I/O pins 
•  40  programmable pull-high I/O pins 
•  40  programmable open-drain I/O pins 
•  40  programmable high-sink/drive I/O pins 
•  External interrupt : P60 
„  Operating voltage range: 
•  2.4V~ 5.5V at 0°C ~ 70°C (Commercial) 
•  2.6V~ 5.5V at -40°C ~ 85°C (Industrial) 
„  Operating frequency range (base on two clocks): 
•  Crystal mode: DC ~ 20 MHz @ 5V ;  
DC ~ 8 MHz @ 3V ; DC ~ 4 MHz @ 2.4V 
•  ERC mode: DC ~ 20 MHz @ 5V ;  
DC ~ 8 MHz @ 3V ; DC ~ 4 MHz @ 2.4V 
•  IRC mode: DC ~ 16 MHz @ 4.5V~5.5V ; 
DC ~ 8 MHz @ 3V ;DC ~ 4 MHz @ 2.4V~5.5V 
•  Internal RC Drift Rate (Ta=25°C, VDD = 5V± 5%, 
VSS=0V) 
Drift Rate 
Internal RC 
Frequency  Temperature 
(-40°C~85°C)
Voltage 
(2.4V~5.5V) 
Process Total
455kHz  ± 5%  ± 5%  ± 4% ± 14%
4 MHz  ± 5%  ± 5%  ± 4% ± 14%
8 MHz  ± 5%  ± 5%  ± 4% ± 14%
16 MHz  ± 5%  ± 5%  ± 4% ± 14%
„  Peripheral configuration 
•  8-bit real time clock/counter (TCC) with selective 
signal sources, trigger edges, and overflow interrupt 
•  Two Pulse Width Modulation (PWMA, PWMB) with 
10-bit resolution shared with Timers A and B 
•  Two 8-bit Timer/Counter 
TC1 : Timer/Counter/Capture mode selection 
TC3: Timer/Counter/PWM/PDO 
•  One 16-bit Timer/Counter 
TC2 : Timer/Counter/Window mode selection 
•  4 programmable Level Voltage Detector (LVD) 
*Vdd power monitors and supports low voltage 
 detector interrupt flag 
•  8 channels Analog-to-Digital Converter with 12-bit 
resolution in Vref mode 
•  Two comparators 
•  Serial transmitter/receiver interface (SPI): 3-wire 
synchronous communication 
•  UART interface: 2-wire asynchronous communication 
•  Power down (Sleep) mode 
•  High EFT immunity (4 MHz, 4 clocks) 
•  I2C function with 7/10 bits address and 8 bits data 
transmit/receive mode 
„  19 available interrupts: (4 external, 15 internal) 
•  External interrupt: P60 
•  TCC overflow interrupt 
•  TC1, TC2, TC3 overflow interrupt 
•  Input-port status changed interrupt (wake up from 
sleep mode) 
•  ADC completion interrupt 
•  PWMA, PWMB period match completion 
•  Comparator high/low interrupt 
•  I2C transfer/receive/stop interrupt 
•  UART TX, RX , RX error interrupt 
•  SPI interrupt 
•  LVD interrupt 
„  Single instruction cycle commands 
„  Four kinds of oscillation range in Crystal Mode 
Crystal Range  Oscillator Mode 
20 MHz ~ 6 MHz  HXT 
6 MHz ~ 1 MHz  XT 
1 MHz ~ 100kHz  LXT1 
32.768kHz  LXT2 
„  Programmable free running watchdog timer 
•  Watchdog Timer: 16.5ms ± 5% with Vdd =5V at 25°C, 
Temperature range ± 5% (-40°C ~+85°C) 
•  Watchdog Timer: 18ms ± 5% with Vdd = 3V at 25°C 
•  Temperature range ± 5% (-40°C~+85°C) 
•  Two clocks per instruction cycle 
„  Package Type:  
•  44-pin QFP  :  EM78Fx68NQ44J/S 
•  40-pin DIP  :  EM78Fx68ND40J/S 
•  32-pin QFN  :  EM78Fx68NQN32J/S 
•  28-pin SKDIP  :  EM78Fx68NK28J/S 
•  28-pin SOP  :  EM78F6x68NSO28J/S 
Note: These are all Green products which do not contain  
hazardous substances.