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Introduction
Specifications
Environmental
Performance curves
Schematics
Physical characteristics
Tape & Reel
Soldering/Washing

Datasheet 3D Models

CST1, CST2 – High Frequency

SMT Current Sense Transformers

Senses current up to 20 Amps
Designed for up to 1 MHz and above
Eight different turns ratios to meet variety of requirements
Two pin-out configurations for different applications
AEC-Q200 Grade 1 (−40°C to +125°C)
Two samples of each value are available in Coilcraft Designer's Kit C389

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Part number

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Count	Unit price
1	$1.92
250	$1.64
500	$1.39
1000	$1.14
2500	$0.99
5000	$0.92

For high volume or non-stock items, request a quote.

Packaging

C = 7" machine-ready reel

. in stock, ready to ship today.

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Part number

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Designer's Kit:

Kit	Values	Price
C389	16 (2 of each)	$50.00

Specifications

Electrical specifications at 25°C.

Part number 1 (Hover for schematics)	Inductance min (µH) 2	DCR max (Ω) 3		Turns Ratio	Volt-time product (V-µs) 4	Frequency (kHz) 5	Current (A) 6	Terminating resistance R_T (Ω) 7	Isolation Voltage (Vrms) 8	Color dot
Part number 1 (Hover for schematics)	Inductance min (µH) 2	Pri	Sec	Pri : Sec	Volt-time product (V-µs) 4	Frequency (kHz) 5	Current (A) 6	Terminating resistance R_T (Ω) 7	Isolation Voltage (Vrms) 8	Color dot
CST1-020L_	81	0.0007	0.40	1 : 20	10.8	46 — >1000	20.0	1.0	500	Red
CST2-020L_	81	0.0007	0.40	1 : 20	10.8	46 — >1000	20.0	1.0	500	Red
CST1-030L_	180	0.0007	0.87	1 : 30	16.2	31 — >1000	20.0	1.5	500	Orange
CST2-030L_	180	0.0007	0.87	1 : 30	16.2	31 — >1000	20.0	1.5	500	Orange
CST1-040L_	320	0.0007	1.1	1 : 40	21.6	23 — >1000	20.0	2.0	500	Yellow
CST2-040L_	320	0.0007	1.1	1 : 40	21.6	23 — >1000	20.0	2.0	500	Yellow
CST1-050L_	500	0.0007	1.5	1 : 50	27	19 — >1000	20.0	2.5	500	Green
CST2-050L_	500	0.0007	1.5	1 : 50	27	19 — >1000	20.0	2.5	500	Green
CST1-060L_	730	0.0007	2.0	1 : 60	32.4	15 — >1000	20.0	3.0	500	Blue
CST2-060L_	730	0.0007	2.0	1 : 60	32.4	15 — >1000	20.0	3.0	500	Blue
CST1-070L_	980	0.0007	4.8	1 : 70	37.8	13 — >1000	20.0	3.5	500	Violet
CST2-070L_	980	0.0007	4.8	1 : 70	37.8	13 — >1000	20.0	3.5	500	Violet
CST1-100L_	2000	0.0007	5.5	1 : 100	54	9 — >1000	20.0	5.0	500	Gray
CST2-100L_	2000	0.0007	5.5	1 : 100	54	9 — >1000	20.0	5.0	500	Gray
CST1-125L_	3000	0.0007	6.5	1 : 125	67.5	7 — >1000	20.0	6.3	500	Black
CST2-125L_	3000	0.0007	6.5	1 : 125	67.5	7 — >1000	20.0	6.3	500	Black

Notes

When ordering, please specify termination and packaging codes: e.g. CST1-125LC or CST2-125LC
Inductance measured across secondary at 100 kHz, 0.1 Vrms.
DCR at 25°C. For other operating temperatures, use this DCR at Temperature calculator.
Volt-time product is for the secondary, between pin 6 and 4 for CST1 and between pin 1 and 3 for CST2.
For specific questions regarding frequency range, please contact us at [email protected].
Primary current of 20 A causes approximately 40°C temperature rise from 25°C ambient. Higher current causes a greater temperature rise. (see Temperature Rise vs Current curve).
Terminating resistor value is based on 1 Volt output with 20 Amps flowing through the primary. Varying terminating resistance increases or decreases output Voltage/Ampere according to the following equation:
R_T (Ohms) = V_out × N_sec / I_in.
500 Vrms, one minute isolation (hipot) winding to winding.

Termination:

L = RoHS compliant tin-silver over tin over nickel over phos bronze (pins 1 – 6); RoHS compliant Matte tin over nickel over copper (pins 7 – 8).
S = non-RoHS tin-lead (63/37) over tin over nickel over phos bronze (pins 1 – 6); non-RoHS tin-lead over gold over nickel over copper (pins 7 – 8). (Special order, added cost)

Packaging:

C = 7″ machine-ready reel. EIA-481 embossed plastic tape (250 parts per full reel). Quantities less than full reel available: in tape (not machine ready) or with leader and trailer ($25 charge).
D = 13″ machine-ready reel. EIA-481 embossed plastic tape. Factory order only, not stocked (1000 parts per full reel).
B = Less than full reel. In an effort to simplify our part numbering system, Coilcraft is eliminating the need for multiple packaging codes. When ordering, simply change the last letter of your part number from B to C.

Environmental

Environmental:

RoHS compliant

Ambient temperature range:

−40°C to +125°C

Storage temperature range:

Component: −40°C to +165°C
Tape and reel packaging: −40°C to +80°C

Maximum part temperature:

+165°C (ambient + temp rise)

Failures in Time (FIT) / Mean Time Between Failures (MTBF):

See FIT/MTBF Calculations

Performance curves

Temperature vs. Current

Schematics

CST1 Series

Terminating resistor (R_T)value is based on 1 Volt output with 20 Amps flowing through the primary. Varying terminating resistance increases or decreases output Voltage/Ampere according to the following equation: R_T (Ohms) = V_out × N_sec / I_in.

CST2 Series

Terminating resistor (R_T) value is based on 1 Volt output with 20 Amps flowing through the primary. Varying terminating resistance increases or decreases output Voltage/Ampere according to the following equation: R_T (Ohms) = V_out × N_sec / I_in.

Physical characteristics

Pinouts

Tape and Reel specification

Parts per reel		Reel dimensions (mm)					Tape dimensions (mm)						Orientation
7" (178 mm)	13" (330 mm)	A	B	C	D	E	W	P	Po	P1	H	T
250	1000*	178/330	60/100	13	22,4	16,4	16	12	4	2	5,6	0,35

General specification

Core Material:

Ferrite

Weight:

0.4 g

Packaging:

250/7″reel;1000/13″ reel; Plastic tape: 16 mm wide, 0.35 mm thick, 12 mm pocket spacing, 5.6 mm pocket depth

Soldering/Washing

Moisture Sensitivity Level (MSL):

1 (unlimited floor life at <30°C / 85% relative humidity)

Resistance to soldering heat:

Three reflows at >217°C for 90 seconds (+260°C ±5°C for 20 – 40 seconds), allowing parts to cool to room temperature between.

Refer to Soldering Coilcraft Components before soldering.

PCB Washing:

Tested to MIL-STD-202 Method 215 plus an additional aqueous wash. More info.

CST1, CST2 – High Frequency

SMT Current Sense Transformers