View zd5221b zd5258b series datasheet:

Spec. No. : C326N3 Issued Date : 2003.04.14 CYStech Electronics Corp. Revised Date : 2014.05.07 Page No. : 1/15 Zener Diode Series ZD52XXBN3 SOT-23 Thermal Characteristics Characteristics Symbol Max Unit Total Device Dissipation FR-5 Board 225 mW PD TA=25°C, Derate above 25°C 1.8 mW/°C Total Device Dissipation 300 mW PD Alumina Substrate**TA=25°C, Derate above 25°C 2.4 mW/°C Thermal Resistance Junction to Ambient RθJA 417 °C/W Junction and Storage Temperature Tj, Tstg -55 to +150 °C *FR-5 - 1.0×0.75×0.062 in. **Alumina - 0.4×0.3×0.024 in. 99.5% alumina. Electrical Characteristic (VF=0.9V Max @IF=10mA for all types.) Test Zener ZZK ZZT Max. Reverse Marking Device Current Voltage IZ=0.25mA IZ=IZT Current Code IZT(mA) VZ(V) (Ω,Max