Hello,
The customer uses SN74LS123 as below circuit. Volume resister is used for Rext.
The customer has two questions. Could you support them?
1) From the datasheet, Rext min value is 5kohm. Customer uses volume resister for Rext, it might be below 5kohm.
What issue occurs if Rext is below 5kohm?
2) The customer wants to know the VR1 value when SN74LS123 output pulse is desired width.
Customer measured VR1 resistance by multi-meter. Power supply was off. VR1 position is 10kohm.
When customer measured VR1 resistance in above condition, the resistance was around 5kohm.
Does this mean SN74LS123 internal circuit affects the measurement. I mean internal resistance was connected in parallel at VR1?
Best regards,
Toshihiro Watanabe