0.4 W Zener — what the power rating means for the rail
The HZS11A3TD-E is a 0.4 W Zener diode from the HZS series, designed for voltage reference and clamping on low-power supply rails. The 0.4 W dissipation ceiling sets the maximum steady-state current the diode can handle: at a nominal Zener voltage around 11 V, continuous current is limited to roughly 36 mA before the junction temperature climbs out of the part's safe operating area. For a field-swap scenario, that means this diode is fine on a logic-level bias rail or a low-current sensor supply, but it is not the part for a power bus clamp where the fault current could push past 50 mA.
No official second source on file
No pin-compatible cross-reference or direct replacement is listed in the manufacturer's documentation. If you are dual-sourcing for supply resilience, you will need to qualify a functionally equivalent Zener from another vendor against your specific voltage and power requirements — the 0.4 W rating and the Zener voltage tolerance are the parameters to match.