CITIZEN CM309E AT-Cut Crystal Unit
Model-Specific Datasheet – CM309E25000000ABJT

1. Ordering Code BreakdownCM309E – 25 000 000 – A – B – J – T

• Frequency: 25.000 MHz
• Frequency Tolerance @ 25 °C: ±30 ppm (code “A”)
• Frequency Stability over –10 °C ~ +60 °C: ±50 ppm (code “B”)
• Load Capacitance: 18 pF (code “J”)
• Packaging: Tape & Reel only (code “T”)

1. Electrical Characteristics @ 25 °C unless notedNominal Frequency (f0): 25.000 MHzVibration Mode: Fundamental AT-cutFrequency Tolerance: ±30 ppmFrequency Stability over Operating Temperature: ±50 ppmOperating Temperature Range (TOPR): –40 °C to +85 °CStorage Temperature Range (TSTR): –55 °C to +125 °CLoad Capacitance (CL): 18 pF (customer-specified)Shunt Capacitance (C0): ≤5 pFMotional (Series) Resistance (R1): ≤50 Ω (guaranteed for 16–30 MHz fundamental)Drive Level (DL): 100 µW max.Insulation Resistance (IR): ≥500 MΩ @ DC 100 V ±15 VFirst-year Aging: ≤±5 ppm @ 25 °C ±3 °C
2. Mechanical & Packaging DataPackage Type: SMD plastic sealed, RoHS-compliantBody Dimensions: 11.7 mm (L) × 4.8 mm (W) × 3.7 mm (H)Solder-pad Layout: 7.6 mm center-to-center, 1.8 mm pad pitch (see datasheet drawing)Reel Quantity: 1 000 pieces per reelReflow Capability: 260 °C peak, JEDEC J-STD-020 compatiblePart Marking Standard:Citizen ID “C”Manufacture date code (year & month)Frequency “25.000” followed by “M” for MHzExample: C 5X25.000M (5 = 2025, X = October)
3. ApplicationsTarget Markets: Consumer electronics, timing modules, micro-controller sub-clocks, IoT edge devices, portable instrumentation.
4. Cautions & Recommendations

• Ultrasonic cleaning or board flexure after mounting may crack the crystal; avoid excessive mechanical stress.
• Drive level must stay ≤100 µW to maintain long-term stability.
• For CL values other than 16 pF / 18 pF / series-resonant, consult Citizen Fine Device sales.
• Storage conditions: dry, <60 % RH, avoid corrosive gases.
• Reflow profile: ramp <3 °C/s, 220 °C max. 60 s above 170 °C, peak 260 °C within 10 s.