Service Forum

darest2 · Nou Venit Joined: 23 Aug 2009 Posts: 5

well need:

C2 - 0.1Uf 50V
D1, D2 y D3 - Zener 4.7V (or 3.2 v a 5.1 v well these are normal voltage. )
D4 - LED
D6- Diode 1N4148
R1 y R2 - Resistances of 10K ohm (1/2 watt)
R3 - Resistance of 4K7 ohm (1/2 watt)
Another: Base of IC 8-pin DIP, conector DB9, etc.

Diagram:

victor · S.F. Boss Joined: 07 Mar 2004 Posts: 2581 Location: Staff

This interface is derived from SIPROG but is dangerous for eeprom and inadequate. A forced design.

1. If you choose to supply the eeprom from the serial port, then you should use a 7805/7803 regulator, because the serial port may reach up to +10 V sometimes and the zenner D1 is just forcing thourgh the R3 resistor. Or, at least, use the zenner diode to drive a power transistor and regulate the line. BTW, R3= 4.7K - no way to supply something serious through it, the current is low Smile

2. Another fault is to use only one COM terminal to supply the eeprom, which is not enough. And not pin#3 which is a Data pin.

3. The zenners are always 5V1 for 5V TTL, or 3.3V for 3V TTL.

Anyway, I don't say it wont work if you change the power system( is SIPROG after all), but is so forced.
_________________
Victor Voinea
ALLservice HQ, Romania.

darest2 · Nou Venit Joined: 23 Aug 2009 Posts: 5

ok bt is most economic use zener, 78033 sometimes is dificult to find yes is a good rectifier and regulator, ar the option 7805 is easy to find, victor do u have another diagram better? , tnx

bob · Posted: Fri Aug 28, 2009 10:55 pm Post subject:

Wow, that is SIPROG all day long, but to supply the eeprom through a 4.7K resistor?..., not a good idea. When the I2C lines are low, this will cut the voltage on Vcc pin as the eeprom gates impedance are lower than that. You have to supply the eeprom with real voltage.

R1 and R2 are also too big. Use 2K2-3K3-4K7. 2k2 are better for in-system trials

Here is the schematic for SIPROG http://www.allservice.ro/forum/dl/simple-i2cprog.pdf

Standalone eeproms can be powered with 2xAA for 2.7V-3.3V ICs, 3xAA for 5V TTL ones. Or USB 5V.

Or this interface for in-system programming
http://www.allservice.ro/forum/dl/driven-i2cprog.pdf

mitratech · Nou Venit Joined: 17 Apr 2009 Posts: 9

Hi Guys,

I wonder if any one can explain to me what is for the functionality the diagram ? Laughing

thanks for the advice