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PIC 16F628 and 16F627

The 16F628 a good replacement device for the 16F84 as it has a lot of usable built in peripherals:


  • 2 x Comparators
  • 1 x UART
  • 1 x CCP
  • 3 x Timers
  • Internal oscillator


  • 2k Program words
  • 224 Bytes SRAM

The 16F84 has 1 peripheral (Timer 0) whereas the 628 has three timers, a USART, a CCP (for Pulse Width Modulation, capture and compare), and two analogue comparator. One other useful feature is that you can switch it from internal 4MHz to slow speed internal37kHz on the fly so you can used it in power sensitive applications (but the 16F628A is a better choice if you need ultra low power operation).

Warning: The 16F628 internal oscillator is not accurate as it is based on an internal RC circuit (See the 16F628A for a precison 1% oscillator).
The two most important features are that there is 2k of program memory and 224 Bytes of RAM.  This last one is nearly four times as much as the 16F84 and for high level language use this makes it much easier to use as it is the resource the you run out of most quickly.

PIC 16F628 Pinout

16F628 pinout diagram

Jump to the 628 bubble diagram.

Difference between the 627 and 628

The only difference is the available program memory (Flash programming area).

Device (16F) Flash program words Ram EEPROM
627 1024x14 224x8 128x8
628 2048x14 224x8 128x8

Jump to bubble diagram device list.

For a summary of each peripheral block click here.

Note: To compare bubble diagrams open each device page in a separate window (a tabbed browser is useful for this) and hit the 'Jump to device' link above then alternately select each view to see the differences between the devices.

16F628, 16F627 Features

There is less memory for the 16F627 (se table above).


The 16F628 pic microcontroller is quite a capable little device having enough memory for useful applications and the only features it lacks are an ADC and I2C capability.  

Not available:

  • ADC
  • I2C

Note: You can get round the lack of I2C by bit-banging programming i.e. controlling a programmable pin without requiring an internal hardware module (see this project for source code) and you could use an external ADC.  A better choice may be the 16F88 that has a built in 10 bit ADC if you need an ADC.

Low Power Operation

The 16F628 has fairly good low power operation 1uA @3V but if you really want to have a battery operated system that lasts longer then the 16F628A has a standby current of 100nA @2V i.e. an order of magnitude better.

TIP: 16F628A has x10 lower current consumption then the 16F628.

Jump from 16f628 resources to
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