tf256.pdf datasheet:

TF256Ordering number : ENA1616ASANYO SemiconductorsDATA SHEETN-channel Silicon Juncton FETElectret Condenser MicrophoneTF256ApplicationsFeatures High gain : GV=2.7dB typ (VCC=2V, RL=2.2k , Cin=5pF, VIN=10mV, f=1kHz) Ultrasmall package facilitates miniaturization in end products [1.0mm 0.6mm 0.27mm (max 0.3mm)] Best suited for use in electret condenser microphone for audio equipments and telephones Excellent transient characteristics Adoption of FBET process Halogen free complianceSpecifications at Ta=25CAbsolute Maximum RatingsParameter Symbol Conditions Ratings UnitGate-to-Drain Voltage VGDO --20 VGate Current IG 10 mADrain Current ID 1 mAAllowable Power Dissipation PD 30 mWJunction Temperature Tj 150 CStorage Temperature Tstg --55 to +150 CPackage Dimensions Product & Package Informationunit : m