Valentina Ttl Model -
| Feature | Ideal Logic (e.g., and gate) | Valentina TTL Model |
|---------|--------------------------------|----------------------|
| Rise/Fall time | 0 or infinitesimal | Finite, load‑dependent |
| Input loading | None | Realistic current draw + C_in |
| Output impedance | 0 Ω | Nonlinear, ~100 Ω (high) / ~10 Ω (low) |
| Ground bounce | Not modeled | Observable (via parasitic inductances) |
| Fan-out effects | Ignored | Directly simulated |
When interfacing a slow 6502 CPU (1 MHz) with a fast VGA controller (25 MHz), signal reflections and timing mismatches occur. The Valentina model’s latching output prevents the VGA controller from seeing spurious CPU bus noise. valentina TTL model
In a SPICE-like netlist, the Valentina TTL model for a single inverter/buffer may be represented as a subcircuit: | Feature | Ideal Logic (e
.SUBCKT VALENTINA_TTL_INV IN OUT VCC GND
* Input stage - multiple-emitter behavior
D1 IN VCC D_ACTIVE
D2 IN GND D_SCHOTTKY
R1 VCC IN 4K
Q1 N001 IN GND NPN_MOD
* Internal drive and totem-pole output
... (simplified)
.ENDS
Alternatively, in higher-level tools (SystemVerilog Real Number Models or IBIS), the model is expressed as a lookup table of I-V curves (for input clamp, output high/low) and V-t tables (ramp rates for transitions). | Feature | Ideal Logic (e.g.
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