Questions about Dejan's flasher interface
 

Hi, All !
I don't understand how work Dejan's flasher interface.
On Nokia 5110 logic level "1" = 2.7V (near) and logic level "0" = 0V (near).
On Vcc=5V-0.6V=4.4V chip SN74HC14 has logic levels (from datasheet):
Vih (High-level input voltage) = 3.15V min;
Vil (Low-level input voltage) = 1.35V max;
Voh (High-level output voltage) = 3.98V min;
Vol (Low-level output voltage) = 0.26V max.
And so:
1. What level was on output of 74HC14 when in input was 2.7V ("1" for Nokia) ???
2. What you say about damaging Nokia's input by logic level of 74HC14 (3.98V min) ???
Please help me understand this.
Sasha.

In input is 2.7 output is logix 0 is input is output same as Your vpp of ic at this case +-4,4V. Most logical IC's won't damage so fast. Between the min and max is a "Forbidden" area. The You don't know sure if the output it is logic "1" or Logic "0".

the 74HC(t)14 is just an inverter

Inp outp
1 0
0 1


[This message has been edited by Blu3fish (edited 12 January 2001).]

Hi Blu3fish!
You say first that "In input is 2.7v output is logix 0" and second say that 2.7v in forbidden zone ???
I don't understand. Sasha.

Hi,To All.

74LS00 :
Operating Voltage=4.75 to 5.25 V
Minimum Logic 1 input = 2 V
Maximum Logic 0 input = 0.8 V
Minimum Logic 1 output = 2.7 V
Maximum Logic 0 output = 0.5 V
Propogation Delay = 9.5 nS
Power Per gate = 2 mW

74C00 :
Operating Voltage= 3 to 15 V
Minimum Logic 1 input = 3.5 V
Maximum Logic 0 input = 1.5 V
Minimum Logic 1 output = 4.5 V
Maximum Logic 0 output = 0.5 V
Propogation Delay = 90 nS
Power Per gate = 2,5 nW

74HC00 :
Operating Voltage= 2 to 6 V
Minimum Logic 1 input = 3.15 V
Maximum Logic 0 input = 0.9 V
Minimum Logic 1 output = 4.4 V
Maximum Logic 0 output = 0.1 V
Propogation Delay = 23 nS
Power Per gate = 0.5 mW at 1 MHz

74HCT00 :
Operating Voltage= 4.5 to 5.5 V
Minimum Logic 1 input = 2 V
Maximum Logic 0 input = 0.8 V
Minimum Logic 1 output = 4 V
Maximum Logic 0 output = 0.33 V
Propogation Delay = 20 nS
Power Per gate = ----

I think this may help you.I didn't run flasher in my old Pentium-75 yet.

Best Regards...

Sorry,

I mean Vin 4,4V not 2,7V
4,4>2,7 so the nokia phone will accept it as a "1"
Also Check post on other subject.
PLZ Next time post it only in one subject.

[This message has been edited by Blu3fish (edited 13 January 2001).]

Yes, Nokia will accept 4.4V as log."1".
But log."1" on Nokia's Tx output 2,7V and I don't know how will accept it 74HC14 chip.



[This message has been edited by SashaM (edited 13 January 2001).]

so, nightxyz, which one of these IC's is the best for the flasher?

thanx

Hi,

I think 74HCT14 is better if you will use external power supply which has 7805 Voltage Regulator.

Best Regards...

Hi!I use 74HCT14 with external power and the flasher works wery fine(tested 6110-6150).
Best regards!

NOTE:

Hello Boys,

i have none externall power, i have power only on LPT port and work only with flas's INTEL, ATMEL, and ST.

I have 4 gates to ground connected on IC 74HC14 and other use's.

And my problem is with reading AMD flash's ID 000122DA !!!