Document 385-1 SMT Current Sensors – CST Series The CST surface mount current sensing transformers are designed for use from 50 kHz to nearly 1 MHz to sense continuous currents to 10 Amps and greater. The CST1 and CST2 differ in pinout numbering and layout in order to meet the requirements of different applications. These transformers feature extremely low primary DC resistance and 500 V isolation between windings. They are available in eight different turns ratios to meet a wide variety of requirements. They are ideal for use in switching power supply applications. Coilcraft Designer’s Kit C389 contains samples of each of the standard parts shown. To order, contact Coilcraft or visit http://order.coilcraft.com. Part number1 CST1 CST2 CST1-020L_ CST1-030L_ CST1-040L_ CST1-050L_ CST1-060L_ CST1-070L_ CST1-100L_ CST1-125L_ CST2-020L_ CST2-030L_ CST2-040L_ CST2-050L_ CST2-060L_ CST2-070L_ CST2-100L_ CST2-125L_ Turns (N) pri : sec 1 : 20 1 : 30 1 : 40 1 : 50 1 : 60 1 : 70 1 : 100 1 : 125 Sensed Terminating Volt-time DCR max (Ohms) current3 resistance R 4 product5 Inductance2 T min (µH) Primary Secondary Iin (A) (Ohms) (V-µsec) 81 180 320 500 730 980 2000 3000 0.0007 0.0007 0.0007 0.0007 0.0007 0.0007 0.0007 0.0007 1. When ordering, please specify termination and packaging codes: 2. 3. 4. 5. 6. 7. CSTX-125LC Termination: L = RoHS compliant matte tin over nickel over phos bronze Special order: T = RoHS tin-silver-copper (95.5/4/0.5) or S = non-RoHS tin-lead (63/37). Packaging: C = 7″ machine-ready reel. EIA-481 embossed plastic tape (250 parts per full reel). B = Less than full reel. In tape, but not machine ready. To have a leader and trailer added ($25 charge), use code letter C instead. D = 13″ machine-ready reel. EIA-481 embossed plastic tape (1000 parts per full reel). Inductance measured between secondary pins at 100 kHz, 0.1 Vrms. Primary current of 10 A causes approximately 25°C temperature rise above 25°C ambient. Higher current causes a greater temperature rise (see Temperature Rise vs Current curve). Terminating resistance (RT) value is based on 1 Volt output with 10 Amps flowing through the primary. Varying terminating resistance increases or decreases output Voltage/Ampere according to the following equation: RT (Ohms) = Vout × Nsec / I in. Maximum volt-time product for the secondary. Storage and operating temperature range -40°C to +125°C. Electrical specifications at 25°C. 0.400 0.870 1.14 1.50 1.98 4.75 5.50 6.50 10 10 10 10 10 10 10 10 16 24 32 41 49 57 81 101 Red Orange Yellow Green Blue Violet Gray Black Typical Circuits CST1 I in 8 6 Pri (1 turn) Sec (N turns) 7 4 8 1 Pri (1 turn) Sec (N turns) 7 3 RT Vout RT Vout CST2 I in Specifications subject to change without notice. Please check our website for latest information. © Coilcraft, Inc. 2009 2.0 3.0 4.0 5.0 6.0 7.0 10.0 12.5 Color dot Document 385-1 Revised 06/11/09 Document 385-2 CST Series Current Sensors Temperature rise (from 25°C) Temperature Rise vs Current Pinouts 80 CST1 CST2 70 8 7 60 3 4 3 4 1 6 1 6 50 40 30 20 10 7 8 Bottom View Bottom View 0 0 2 4 6 8 10 12 14 16 18 20 Current (A rms) Dimensions 0.230 5,84 0.240 6,10 Color dot by pin 1 indicates part number 0.209 max 5,3 0.004 / 0,10 0.315 max 8,0 0.320 max 8,13 Recommended Land Pattern 0.118 3,0 0.023 ±0.008 0,6 ±0,2 0.073 ±0.008 1,85 ±0,2 0.098 2,5 0.106 2,7 0.073 1,85 0.047 1,2 0.063 1,6 0.079 ±0.008 2,0 ±0,2 0.051 1,3 0.051 1,3 Weight: 11.0 – 11.9 g Tape and reel: 250/7″ reel; 1000/13″ reel 16 mm tape width For packaging data see Tape and Reel Specifications section. Specifications subject to change without notice. Please check our website for latest information. © Coilcraft, Inc. 2009 Document 385-2 Revised 06/11/09